PVTRIN Training course Solar Installers handbook
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PVTRIN Training course- Solar installers handbook ii
CONTENTS
CONTENTS
CONTENTS iii 1.5.3. Making cities greener 10 1. SOLAR BASICS 2 1.5.4. PV jobs 10 1.5.5. No limits 11 1.1. Solar Photovoltaic (PV) Energy 2 2. DESIGN PRINCIPLES 14 1.1.1. The sun as an energy source 2 1.1.2. What does photovoltaic (PV) 2.1. On Site Visit 14 mean? 2 2.1.1. Customer Needs 15 1.1.3. Solar irradiance (radiation) 2 2.1.2. Climate Conditions 15 1.1.4. Enormous potential 3 2.1.3. Shading 15 1.2. PV System 4 2.1.4. Array Orientation and Tilt 18 1.2.1. PV cells and modules 4 2.1.5. Μοunting Methods 19 1.2.2. Inverters 5 2.1.6. BOS Locations 21 1.2.3. Batteries and charge controllers 5 2.1.7. Load Description 22 1.2.4. Other system components 5 2.1.8. Performance ratio 22
1.3. PV Technologies 5 2.2. System Sizing and Design 23 1.3.1. First generation (Crystalline 2.2.1. Basics 23 silicon technology) 5 2.2.2. Inverters 24 1.3.2. Second generation (Thin Films) 6 2.2.3. Number of strings 27 1.3.3. Third generation photovoltaics 7 2.2.4. Sizing of cables 27 1.4. Types of PV systems and 2.2.5. Blocking Diodes 29 applications 8 2.2.6. Earthing 29 1.4.1. Grid-connected systems 8 2.2.7. Lightning protection 30 1.4.2. Stand-alone, off-grid and hybrid 2.2.8. Stand-alone PV system sizing 32 systems 9 2.2.9. Legal Aspects 38
1.5. Benefits of PV technology 9 2.3. Simulation software 38 1.5.1. Environmental footprint of PV 10 2.3.1. PV analysis and planning 1.5.2. Improving grid efficiency 10 software 39 2.3.2. Software tools for site analysis 41 PVTRIN Training course- Solar installers handbook iii
2.4. Economics and Environmental 3.5. Design parameters and Issues 42 performance factors 75 2.4.1. Economic Aspects 42 3.5.1. Location and urban planning 75 2.4.2. Environmental Issues 44 3.5.2. Orientation and tilt 76 3.5.3. Shading 78 2.5. Standards and regulations 47 3.5.4. Construction requirements 79 2.5.1. International Standards and Regulations 47 3.6. Examples from the residential 2.5.2. National Standards and sector 80 Regulations 47 3.7. Exercises 83 2.6. Databases 50 3.7.1. Mounting and building 2.7. Exercises 54 integration options 83 3.7.2. BIPV and BAPV on roofs 83 2.7.1. Case studies 54 3.7.3. BIPV and BAPV on facades 84 2.7.2. Multiple Choice Questions 56 3.7.4. Glass roofs, shading systems and 2.7.3. Correct–Wrong Questions 58 other applications 84 2.7.4. More Practice 59 3.7.5. Design parameters and performance factors 85 3. BAPV and BIPV 62 4. INSTALLATION – SITEWORK 88 3.1. Mounting and building integration options 62 4.1. Working safely with PV 88 3.1.1. BAPV and BIPV 62 4.1.1. Safe Working Practices 88 3.1.2. Building integration options 62 4.1.2. Potential hazards 88 3.2. BIPV and BAPV on roofs 64 4.1.3. Safety with electrical installations 89 3.2.1. PV modules on flat roofs 64 4.1.4. Security provisions for work at 3.2.2. PV modules on pitched roofs 65 height. 92 3.3. PV on facades 67 4.1.5. Safety equipment 94 4.1.6. Fire protection 94 3.3.1. Options for integration 67 4.1.7. Other Risks 95 3.3.2. BAPV on facades 68 3.3.3. BIPV on facades 68 4.2. Installation plan 96 3.3.4. Mounting requirements 71 4.2.1. Work Sequences 97 3.4. Glass roofs, shading systems and 4.2.2. Technical documentation 97 other applications 71 4.2.3. Technical drawings 98 3.4.1. Glass roofs 71 4.2.4. Tools and Equipment 98 3.4.2. Shading devices 72 4.2.5. Safety Plan 99 3.4.3. Other applications 74 4.3. Electrical components installation 99 4.3.1. Mitigate electrical hazards 99
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CONTENTS
4.3.2. Install grounding system 100 5.7. Blackpool Centre for Excellence in 4.3.3. Conduit 102 the Environment 146 4.3.4. Protections 102 6. EXAMPLE INSTALLATION OF A SMALL 4.3.5. Circuit Conductors 103 SCALE PV ON BUILDING 150
4.4. Equipment installation 103 6.1. Used software Tool – PV*Sol 150 4.4.1. Photovoltaic module 103 4.4.2. Inverter 107 6.2. Description of a building 150 4.4.3. Storage Battery System 108 6.3. Selection of the equipment 151 4.4.4. Current / Voltage Regulator 113 6.4. Determination of climate conditions151 4.5. Mechanical Components Installation116 4.5.1. Adapting the Mechanical Design 116 6.5. Determination a appropriate size of PV system 152 4.5.2. Structure Support 116 4.5.3. Anchorage Systems 119 6.6. Selection of an inverter 153 4.6. Grid-connected PV Systems 121 6.7. Estimation of shadings 153 4.6.1. Topology of the installations 122 6.8. Estimating a energy production 153 4.7. Stand-alone PV System 123 6.9. Safety plan of a small scale 4.8. Completing the PV installation 124 installation 154 4.8.1. Documentation to the customer 127 7. MAINTENANCE AND 4.9. Installation checklist 128 TROUBLESHOOTING 158
4.10. Exercises 130 7.1. Maintenance plan 158 4.10.1. Questions 130 7.1.1. Periodical inspection 158 7.1.2. Dirt accumulation 158 5. CASE STUDIES – BEST PRACTICES 134 7.1.3. Battery maintenance 159 5.1. PV installation in Aurinkolahti 7.1.4. Inverter maintenance 159 Comprehensive School 134 7.1.5. Charge controller maintenance 160 5.2. PV plant on the Kungsmad School 136 7.1.6. Maintenance tools and equipment 160 5.3. Solar power plant BERDEN 138 7.1.7. Shading 161 7.1.8. Electrical connections check 161 5.4. PV system on school in Šmartno ob 7.1.9. Other damages 161 Dreti 140 7.2. Typical mistakes and failures 162 5.5. Athens Metro Mall 142 7.3. Diagnostic procedures 164 5.6. Roof and wall mounted system in 7.3.1. Visual inspection procedures 164 Finland 144
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7.3.2. Performance monitoring 164
7.4. Documentation to the customer 165
7.5. Maintenance checklist 165
7.6. Exercises 166 7.6.1. Questions & Answers 166
8. QUALITY MANAGEMENT AND CUSTOMER CARE 168
8.1. Quality principles 168
8.2. EU standards for PV 169
8.3. Customer care 170 8.3.1. General 170 8.3.2. Selling Solar 170 8.3.3. Quotations and contracts 171 8.3.4. Completing the work 172 8.3.5. Final testing, commissioning and handover 172 8.3.6. Warranties and after sales service 172
8.4. Exercises 173
9. FURTHER READING 174
9.1. Further Reading 174
9.2. Further Reading, in Greek 176
10. GLOSSARY OF TERMS 177
ANNEXEX 182
LIST OF TABLES 190
LIST OF FIGURES 192
REFERENCES 196
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SOLAR BASICS 1
PVTRIN Training course- Solar installers handbook 1
1. SOLAR BASICS FIGURE 1. EXAMPLE OF THE PHOTOVOLTAIC EFFECT. (Source: EPIA) 1.1. Solar Photovoltaic (PV) Energy
1.1.1. The sun as an energy source
The sun is the most important source of energy for all processes on earth. The sun provides heat and contributes to critical processes such as photosynthesis, being an energy source for the survival of all species on earth.
When it comes to energy in the more common sense of the word, today’s methods to produce energy on earth use solar energy – either directly or in an indirect way. Biological material from the past has been transformed into fossil fuels (oil and coal), but also wind power, hydropower and bio- energy are indirect forms of solar energy.
Solar photovoltaics on the other hand is a direct form of solar energy.
1.1.2. What does photovoltaic (PV) mean? 1.1.3. Solar irradiance (radiation)
Photovoltaic (PV) systems contain cells that A large amount of statistical data on solar convert sunlight into electricity. Inside each energy availability is collected globally. For cell there are layers of a semi-conducting example, the US National Solar Radiation material. Light falling on the cell creates an database has 30 years of solar irradiance and electric field across the layers, causing meteorological data from 237 sites in the electricity to flow. The intensity of the light USA. The European Joint Research Centre determines the amount of electrical power (JRC) also collects and publishes European each cell generates. solar irradiance data from 566 sites.
A photovoltaic system does not need bright Different types of solar irradiance data are sunlight in order to operate. It can also available. It is important to distinguish generate electricity on cloudy and rainy days between1: from reflected sunlight.
1 Definitions sources from: http://www.3tier.com/en/support/glossary/ PVTRIN Training course- Solar installers handbook 2
1 SOLAR BASICS
- Direct Normal Irradiance (DNI): the amount Depending on the type of PV system, of solar radiation received per unit area by a different irradiance data has to be used. PV surface that is always held perpendicular (or systems should be designed in such a way normal) to the rays that come in a straight that they capture as much sunlight as line from the direction of the sun at its possible. Therefore the orientation and current position in the sky. inclination are of critical importance. As a consequence, it is suggested to use the global - Diffuse Irradiance (DIF): the amount of in-plane irradiance for power output radiation received per unit area by a surface calculations. (not subject to any shade or shadow) that does not arrive on a direct path from the sun, but has been scattered by molecules FIGURE 3. SOLAR IRRADIATION AROUND THE WORLD. (Source: Gregor and particles in the atmosphere or reflected Czisch, ISET, Kassel, Germany) by the ground and comes equally from all directions. - Albedo Irradiance: A third type of radiation called albedo, and is direct or diffuse radiation that reflected in the soil or on surfaces close to him (snow, lakes, walls of buildings, and so on).
FIGURE 2. TYPES OF SOLAR IRRADIANCE. (Source: Tknika, 2004)
1.1.4. Enormous potential There is more than enough solar irradiance available to satisfy the world’s energy demands. On average, each square metre of land on Earth is exposed to enough sunlight to generate 1,700 kWh of energy every year using currently available technologies. The total solar energy that reaches the Earth’s surface could meet existing global energy - Global Horizontal Irradiance (GHI): the total needs 10,000 times over. amount of shortwave radiation received from above by a horizontal surface. It While only a certain part of solar irradiance includes both Direct Normal Irradiance can be used to generate electricity, this (DNI) and Diffuse Horizontal Irradiance ‘efficiency loss’ does not actually waste a (DIF). finite resource, as it does when burning fossil fuels for power. - Global In-Plane Irradiance: the total amount of radiation (both DNI and DIF) received Where there is more sun, more power can be from above by an inclined surface. generated. The sub-tropical areas of the
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world offer some of the best locations for units called PV modules. Thin sheets of EVA solar power generation. The average energy (Ethyl Vinyl Acetate) or PVB (Polyvinyl received in Europe is about 1,200 kWh/m2 Butyral) are used to bind cells together and to per year (GHI). This compares with 1,800 to provide weather protection. The modules are 2,300 kWh/m2 per year in the Middle East normally enclosed between a transparent (GHI). cover (usually glass) and a weatherproof backing sheet (typically made from a thin EPIA has calculated that Europe’s entire polymer or glass). Modules can be framed for electricity consumption could be met if just extra mechanical strength and durability. 0.34% of the European land mass was FIGURE 4. covered with photovoltaic modules (an area PV MODEULE CELL’S CONNECVTION. (Source: Tknika,2004) equivalent to the Netherlands). International Energy Agency (IEA) calculations show that if 4% of the world’s very dry desert areas were used for PV installations, the world’s total primary energy demand could be met.
There is enormous untapped potential. Vast areas such as roofs, building surfaces, fallow land and desert could be used to support Modules can be connected to each other in solar power generation. For example, 40% of series (known as an array) to increase the the European Union’s total electricity total voltage produced by the system. The demand in 2020 could be met if all suitable arrays are connected in parallel to increase roofs and facades were covered with solar the system current. panels (Sunrise project. 2011)
1.2. PV System FIGURE 5. DIFFERENT CONFIGURATION OF SOLAR POWER SYSTEMS. The key parts of a solar PV energy generation (Source: DTI,,2006) system are: - Photovoltaic cells and modules to collect sunlight, - An inverter to transform direct current (DC) to alternate current (AC), - A set of batteries and charge controller for stand-alone PV systems, - Other system components. All system components, excluding the PV modules, are referred to as the balance of system (BOS) components. The power generated by PV modules varies from a few watts (typically 20 to 60 Wp) up to 1.2.1. PV cells and modules 300 to 350 Wp depending on module size and the technology used. Low wattage modules The solar cell is the basic unit of a PV system. are typically used for stand-alone applications Cells are connected together to form larger where power demand is generally low.
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Modules can be sized according the site can be added to the system. All these where they will be placed and installed components are referred to as the Balance of quickly. They are robust, reliable and System (BoS). The most common weatherproof. Module producers usually components are mounting structures, guarantee a power output of 80% of the Wp, tracking systems, electricity meters, cables, even after 20 to 25 years of use. Module power optimisers, transformers, combiner lifetime is typically considered of 25 years, boxes, switches, etc. although it can easily reach over 30 years.
FIGURE 6. 1.2.2. Inverters DIFFERENT CONFIGURATION OF SOLAR POWER SYSTEMS. (Source: EPIA) Inverters convert the DC power generated by a PV module to AC power. This makes the system compatible with the electricity distribution network and most common electrical appliances. An inverter is essential for grid-connected PV systems. Inverters are offered in a wide range of power classes ranging from a few hundred watts (normally for stand-alone systems), to several kW (the most frequently used range) and even up to 2,000 kW central inverters for large-scale systems. 1.3. PV Technologies
1.2.3. Batteries and charge controllers PV technologies are classified as first, second or third generation. First generation Stand-alone PV systems require a battery to technology is the basic crystalline silicon (c- store energy for future use. Lead-acid or Si). Second generation includes Thin Film lithium-ion batteries are typically used. New technologies, while third generation includes high-quality batteries, designed specifically concentrator photovoltaics, organics, and for solar applications and with a life of up to other technologies that have not yet been 15 years, are now available. The actual commercialised at large scale. lifetime of a battery depends on how it is managed. 1.3.1. First generation (Crystalline silicon technology) Batteries are connected to the PV array via a charge controller. The charge controller Crystalline silicon cells are made from thin protects the battery from overcharging or slices (wafers) cut from a single crystal or a discharging. It can also provide information block of silicon. about the state of the system or enable metering and payment for the electricity The type of crystalline cell produced depends used. on how the wafers are made. The main types of crystalline cells are: 1.2.4. Other system components - Mono crystalline (mc-Si), In addition to the modules and inverter, a - Polycrystalline or multi crystalline (pc-Si), large number of other system components
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- Ribbon and sheet-defined film growth module size for Thin Film technologies. As a (ribbon/sheet c-Si). result they vary from 0.6 to 5.7 m² depending on the technology. Very large modules are of The most common cells are 12.7 x 12.7 cm (5 great interest to the building sector as they x 5 inches) or 15 x 15 cm (6 x 6 inches) and offer efficiencies in terms of handling and produce 3 to 4.5 W – a very small amount of price. power. A standard c-Si module is made up of about 60 to 72 solar cells and has a nominal Four types of Thin Film modules are power ranging from 120 to 300 Wp commercially available: depending on size and efficiency. Amorphous silicon (a-Si) The typical module size is 1.4 to 1.7 m² although larger modules are also The semiconductor layer is only about 1 µm manufactured (up to 2.5 m²). These are thick. Amorphous silicon can absorb more typically utilised for Building Integrated sunlight than c-Si structures. However, a Photovoltaic (BIPV) applications. lower flow of electrons is generated which leads to efficiencies that are currently in the Crystalline silicon is the most common and range of 4 to 8%. An increasing number of mature technology representing about 80% companies are developing light, flexible a-Si of the market today. Cells turn between 14 modules perfectly suitable for flat and curved and 22% of the sunlight that reaches them industrial roofs. into electricity. For c-Si modules, efficiency ranges between 12 and 19%. Multi-junction thin film silicon (a-Si/µc-Si) This consists of an a-Si cell with additional 1.3.2. Second generation (Thin Films) layers of a-Si and micro-crystalline silicon (µc- Si) applied onto the substrate. The µc-Si layer Thin Film modules are constructed by absorbs more light from the red and near- depositing extremely thin layers of infrared part of the light spectrum. This photosensitive material on to a low-cost increases efficiency by up to 10%. The backing such as glass, stainless steel or thickness of the µc-Si layer is in the order of 3 plastic. Once the deposited material is µm, making the cells thicker but also more attached to the backing, it is laser-cut into stable. multiple thin cells. Cadmium telluride (CdTe) Thin Film modules are normally enclosed between two layers of glass and are CdTe Thin Films cost less to manufacture and frameless. If the photosensitive material has have a module efficiency of up to 11%. This been deposited on a thin plastic film, the makes it the most economical Thin Film module is flexible. This creates opportunities technology currently available. to integrate solar power generation into the fabric of a building (BIPV) or end-consumer Copper, indium, gallium, applications. (di)selenide/(di)sulphide (CIGS) and copper, indium, (di)selenide/(di)sulphide (CIS) Standard Thin Film modules have lower CIGS and CIS offer the highest efficiencies of nominal power (60 to 120 Wp) and their size all Thin Film technologies. Efficiencies of 20% is generally smaller. However, there is no have been achieved in the laboratory, close common industry agreement on optimal PVTRIN Training course- Solar installers handbook 6
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to the levels achieved with c-Si cells. The After more than 20 years of research and manufacturing process is more complex and development, third generation solar devices less standardised than for other types of cells. are beginning to emerge in the marketplace. This tends to increase manufacturing costs. Current module efficiencies are in the range Many of the new technologies are very of 7 to 12%. promising. One exciting development is organic PV cells. These include both fully 1.3.3. Third generation photovoltaics organic PV (OPV) solar cells and the hybrid dye-sensitised solar cells (DSSC). Concentrator photovoltaics (CPV) Third generation technologies that are Concentrator photovoltaics (CPV) utilise beginning to reach the market are called lenses to focus sunlight on to solar cells. The “emerging” and can be classified as: cells are made from very small amounts of highly efficient, but expensive, semi- - Advanced inorganic Thin Films such as conductor PV material. CPV cells can be spherical CIS and Thin Film polycrystalline based on silicon or III-V compounds silicon solar cells. (generally gallium arsenide or GaA). - Organic solar cells which include both fully organic and hybrid dye-sensitised solar 2 CPV systems use only direct irradiation . They cells. are most efficient in very sunny areas which - Thermo-photovoltaic (TPV) low band-gap have high amounts of direct irradiation. cells which can be used in combined heat and power (CHP) systems. The concentrating intensity ranges from a factor of 2 to 100 suns (low concentration) up Third generation PV products have a to 1000 suns (high concentration). significant competitive advantage in Commercial module efficiencies of 20 to 25% consumer applications because of the have been obtained for silicon based cells. substrate flexibility and ability to perform in Efficiencies of 25 to 30% have been achieved dim or variable lighting conditions. Possible with GaAs, although cell efficiencies well application areas include low-power above 40% have been achieved in the consumer electronics (such as mobile phone laboratory. rechargers, lighting applications and self- powered displays), outdoor recreational The modules have precise and accurate sets applications, and BIPV. of lenses which need to be permanently oriented towards the Sun. This is achieved In addition to the emerging third generation through the use of a double-axis tracking PV technologies mentioned, a number of system. Low concentration PV can be also novel technologies are also under used with one single-axis tracking system and development: a less complex set of lenses. - Active layers can be created by introducing quantum dots or nanotechnology particles. Other third generation PV This technology is likely to be used in concentrator devices. - Tailoring the solar spectrum to wavelengths with maximum collection efficiency or increasing the absorption level of the solar cell. These adjustments PVTRIN Training course- Solar installers handbook 7
can be applied to all existing solar cell integrated into the roof or building facade technologies. (known as Building Integrated PV systems – or BIPV). FIGURE 7. OVERVIEW OF EFFICIENCY OF PV TECHNOLOGIES. (Source: EPIA 2011, Photon International, February 2011, EPIA analysis) Modern PV systems are not restricted to square and flat panel arrays. They can be curved, flexible and shaped to the building’s design. Innovative architects and engineers are constantly finding new ways to integrate PV into their designs, creating buildings that are dynamic, beautiful and provide free, clean energy throughout their life.
1.4.1. Grid-connected systems
When a PV system is connected to the local electricity network, any excess power that is generated can be fed back into the electricity grid. Under a FiT regime, the owner of the PV system is paid, according to the law, for the power generated by the local electricity provider. This type of PV system is referred to as being ‘on-grid.’
Most solar PV systems are installed on homes and businesses in developed areas. By connecting to the local electricity network, owners can sell their excess power, feeding 1.4. Types of PV systems and clean energy back into the grid. When solar applications energy is not available, electricity can be drawn from the grid.
PV systems can provide clean power for small Solar systems generate direct current (DC) or large applications. They are already while most household appliances utilise installed and generating energy around the alternating current (AC). An inverter is world on individual homes, housing installed in the system to convert DC to AC. developments, offices and public buildings. Large industrial PV systems can produce Today, fully functioning solar PV installations enormous quantities of electricity at a single operate in both built environments and point respectful of the environment. These remote areas where it is difficult to connect types of electricity generation plants can to the grid or where there is no energy produce from many hundreds of kilowatts infrastructure. PV installations that operate in (kW) to several megawatts (MW). isolated locations are known as stand-alone systems. In built areas, PV systems can be The solar panels for industrial systems are mounted on top of roofs (known as Building usually mounted on frames on the ground. Adapted PV systems – or BAPV) or can be PVTRIN Training course- Solar installers handbook 8
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However, they can also be installed on large 1.4.2.1. Off-grid systems for rural industrial buildings such as warehouses, electrification airport terminals or railway stations. The system can make double-use of an urban Typical off-grid installations bring electricity space and put electricity into the grid where to remote areas or developing countries. energy-intensive consumers are located. They can be small home systems which cover a household’s basic electricity needs, or larger solar mini-grids which provide enough TABLE 1. power for several homes, a community or TYPICAL TYPE AND SIZE OF APPLICATIONS PER MARKET SEGMENT FOR GRID-CONNECTED PV SYSTEMS. (Source: Solar small business use. Generation VI, EPIA and Greenpeace) 1.4.2.2. Off-grid industrial applications Type of Market segment application Off-grid industrial systems are used in remote Residential Commercial Industrial Utility- scale areas to power repeater stations for mobile
10kWp- 100kWp- telephones (enabling communications), <10 kWp 100 kWp 1MWp >1MWptraffic signals, marine navigational aids, Ground- X X mounted remote lighting, highway signs and water Roof-top X X X treatment plants among others. Both full PV Integrated and hybrid systems are used. Hybrid systems to X X are powered by the Sun when it is available facade/roof and by other fuel sources during the night
and extended cloudy periods. 1.4.2. Stand-alone, off-grid and hybrid Off-grid industrial systems provide a cost- systems effective way to bring power to areas that are very remote from existing grids. The high cost Off-grid PV systems have no connection to an of installing cabling makes off-grid solar electricity grid. An off-grid system is usually power an economical choice. equipped with batteries, so power can still be used at night or after several days of low 1.4.2.3. Consumer goods irradiance. An inverter is needed to convert the DC power generated into AC power for PV cells are now found in many everyday use in appliances. electrical appliances such as watches, calculators, toys, and battery chargers (as for Most standalone PV systems fall into one of instance embedded in clothes and bags). three main groups: Services such as water sprinklers, road signs, lighting and telephone boxes also often rely - Off-grid systems for the electrification of on individual PV systems. rural areas,
- Off-grid industrial applications, - Consumer goods. 1.5. Benefits of PV technology
PV technology exploits the most abundant source of free power from the Sun and has the potential to meet almost all of mankind’s energy needs. Unlike other sources of energy, PVTRIN Training course- Solar installers handbook 9
PV has a negligible environmental footprint, responsible for large amounts of greenhouse can be deployed almost anywhere and gas emissions, if the power supply is not utilises existing technologies and renewable. Solar power will have to become manufacturing processes, making it cheap an integral and fundamental part of and efficient to implement. tomorrow’s positive energy buildings.
1.5.1. Environmental footprint of PV 1.5.4. PV jobs To meet the challenge of this market The energy it takes to make a solar power expansion, the sector needs a diverse and system is usually recouped by the energy qualified workforce. Close to 220,000 people costs saved over one to three years. Some were employed by the solar photovoltaic new generation technologies can even industry at the beginning of 2010. This recover the cost of the energy used to number includes employment along the produce them within six months, depending entire value chain world-wide: production of on their location. PV systems have a typical PV products and equipment needed for their life of at least 25 years, ensuring that each production, development and installation of panel generates many times more energy the systems, operation and maintenance as than it costs to produce. well as financing of solar power plants and R&D.
1.5.2. Improving grid efficiency While manufacturing jobs could be concentrated in some global production PV systems can be placed at the centre of an hubs, the downstream jobs (related to energy generation network or used in a installation, operation and maintenance, decentralised way. Small PV generators can financing and power sales) are, for the be spread throughout the network, moment, still mainly local. connecting directly into the grid. In areas that PV will provide an increasing number of jobs are too remote or expensive to connect to during the next decades. To estimate the the grid, PV systems can be connected to employment potential, one can use an batteries. assumption of 30 jobs per MW installed 1.5.3. Making cities greener resulting in a forecast of 1.7 million jobs worldwide by 2020. However, the need for quality installations calls for skilled labour With a total ground floor area over 22,000 and appropriate education especially km2, 40% of all building roofs and 15% of all qualified and certified installers. Electricians, facades in EU 27 are suited for PV roofers, and other construction workers are applications. This means that over 1,500 GWp to bring their knowledge together in a new of PV could technically be installed in Europe kind of job description which could be called which would generate annually about “solar installer”. 1,400TWh, representing 40% of the total electricity demand by 2020. PV can seamlessly integrate into the densest urban environments. City buildings running lights, air-conditioning and equipment are PVTRIN Training course- Solar installers handbook 10
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1.5.5. No limits
There are no substantial limits to the massive deployment of PV. Material and industrial capability are plentiful and the industry has demonstrated an ability to increase production very quickly to meet growing demand. This has been demonstrated in countries such as Germany and Japan which have implemented proactive PV policies.
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DESIGN PRINCIPLES 2
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During the site assessment the installer 2. DESIGN PRINCIPLES should collect information that will be used to estimate the output of the system and its 2.1. On Site Visit cost. Information should be detailed on the following issues: Before starting the planning and designing of a PV system the installer should conduct a - the available surface area, site visit and check whether the site is - the potential location of the array, suitable or not for the installation. For this - possible location of the auxiliary scope, the installer should have maps, equipment, inclinometer, solar sitting device, camera, tape measure and compass (SEIS, 2006). - the wire runs, Depending on the location and the - shading, conditions, safety gears may also be needed. - terrain features (ground mounted PVs), FIGURE 8. - orientation, angle of inclination in case of a STEPS TO BE FOLLOWED DURING ON SITE VISIT roof applied PV system.
Check potential If the roof structure appears to be locations Search for weather inadequate to support the PV array the data & extreme installer should ask for an engineer’s advice. conditions Health and safety risks to be considered Perform shadow analysis, check for During the onsite visit the installer should obstacles, terrain examine health and/or safety risks that are peculiarities Choose optimum location, possible to occur during the PV system check for risks installation. He should check for ways
In case of BAPV, accessing the site when working at heights check available and identify risks that may appear from surfaces falling objects. Moreover, when checking for Identify customer’s needs. Check if the the wire runs the installer should decide the system will be used on appropriate equipments in order to safely summer , winter or Define throughout the year and connect the system to the grid. In case of appropriate slippery glazed tiles or damaged roofing he technologies & mounting should be able to decide if the roof is Estimate best orientation appropriate for the installation. It is and tilt absolutely necessary to respect the safety measures when working on these roofs. The Check for the BOS PV installer should also have in mind the location weather conditions that he will probably have Check for potential paths for connecting to to face and to avoid installing the system on the grid, Check for Check for potential icy or windy days if the system is difficult to prospective regulation wire runs be installed. barriers
Make a draft cost estimation and advice customer if the investment worth it
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2 DESIGN PRINCIPLES
2.1.1. Customer Needs The location of the site is of high importance for the system’s efficiency; northern areas Τhe installer should have a clear picture of have less solar energy available (FIGURE 9). the customer’s needs, before determine if Solar maps, illustrating the solar potential in the installation is feasible and then to start different European locations, can be found in designing the system. the Photovoltaic Geographical Information During the first on site visit the installer System (PVGIS). should discuss with the customer important PV systems shall be designed to withstand all issues concerning the amount of money weather conditions, such as lightning, wind expected to be spent on the system, existing up to 80 miles per hour, and extreme subsidies or Feed-in-Tariff (FIT) schemes and temperatures; these extreme conditions may the size of the system. The selected system gradually reduce its energy productivity. should meet the owner’s needs and expectations. PV's are more efficient at lower temperatures so they should be installed at a distance from The installer should be prepared to answer roofs ground etc. in order to be ventilated. any questions about the proposed system FIGURE 9. and to provide alternative choices based on SOLAR RADIATION IN EUROPE. (Source: PVGIS various factors including site considerations (http://re.jrc.ec.europa.eu/ pvgis/ 2011) and customer needs. Some common questions frequently arise are: - What is the PV phenomenon? - How does a solar cell work? - What are the advantages & disadvantages of PV system? - Is my site/roof suitable for a PV system? - What is the lifetime of a PV system? - How much energy will the PV system produce per year? - What happens to the power supply in cloudy days? 2.1.3. Shading - Do PV systems have a high operating cost? On-site visits involve the assessment of - What kind of maintenance is required? whether the location of the PV system will be shaded and at which extend. Shading may be - Are there any grants, tax reductions or FITs one of the most important environmental available? parameters and one of the most critical - What is the payback period? parameters for energy loss in a PV array (PVResources, 2011). A detailed description of the surroundings is required to perform 2.1.2. Climate Conditions the shading calculations. The more solar radiation and the more uniform solar radiation on the array, the highest efficiency of the system will achieved. PVTRIN Training course- Solar installers handbook 15
Shading is crucial especially between 08:00 Even when half of a cell is shaded, the result am and 17:00 pm. A minimum of six hours of is the same as if half of a row is shaded. The un-shaded operation is required for best power decrease will be the same and system performance (PVResources, 2011). proportional to the percentage of area shaded (Sunglobal, 2011). An un-shaded surface can only be found if the ground is flat and no obstacles are nearby. In In addition, the PV module may be damaged case that objects (trees, electricity poles, during shading, if too many cells are buildings etc.) are far away from the potential connected in series. This type of damage can PV field, it can be assumed that there will be be avoided if bypass diodes are used no shadings. However, in most cases, various (Wenham et al, 2007). objects exist in the surroundings and they cannot be removed (Quaschning & Hanitsch, Types of shading 1998). Shading in PVs can be sorted in the following categories: In a large number of BIPV systems in Europe, shading leads to annual yield reductions - temporary, between 5% and 10% (Drifa et al, 2008). - resulting from the location, Potential shading sources can be trees and - self-shading, bushes, neighbouring buildings and self- - resulting from buildings (DGS, 2008). shading by the building itself in case that the As temporary shading, fallen leaves, snow, air PV is sited in urban areas. Even small pollution and dirt may be considered. The obstacles like chimneys, satellite dishes, losses caused by this type of shading are telephone poles etc. should not be neglected estimated as a 2-5% and may be overcome during the site assessment. To minimize the through proper arrangement and angle of the influence of PV array shading, if cannot be panels. The effect of this type of shading can avoided, different optimization techniques be further reduced by cleaning the PV array may be used (PVresources, 2011). with water. A 15⁰ tilt allows the solar panel to When the PV system is sited in a field the self-clean. most common cause of severe shading is a Shading, resulting from the location, is tree or a group of trees (DTI, 2008). Shading caused by the surroundings; obstacles of this depends on the height of the tree, the type range from tall trees to neighbouring distance from the array and the direction of buildings. The PV installer has to identify if the tree with respect to the array. Trees that there are any obstacles which will shade the are between east and south east or between array and to examine if this can be avoided west and south west of the array can cause by moving them. However, if this is not bigger problems than those to the south, possible the shading effect can be minimized since the sun is lower in the sky in these if taken into account during the initial design directions (DTI, 2008). If possible, the trees stage. should be restricted in height so that they do not shade the array. In any case, the installer may advise the customer on how to avoid this type of Partial-shading of even one cell of a 36-cell shadowing (e.g. to trim the trees causing the module can reduce significantly its power problem). output. PV Cells are connected in a series string; so a cell not operating properly will result to reduced power for the whole array. PVTRIN Training course- Solar installers handbook 16
2 DESIGN PRINCIPLES
FIGURE 10. In this case (Kirchensteiner, 2010): SHADING FROM NEIGHBORING OBSTACLES. (Source: Energia e Domotica, Flickr, 2011). Lmin= 2 x H H: the height of the obstacle Lmin is calculated for the Winter Solstice. Based on the thickness of the object d, the optimum distance Lmin can be calculated using the similar triangle relations of the sun tangents which touch the object (FIGURE 12). The optimum distance Lopti from the modules is determined as:
Ls: distance Earth to sun = 150. 106 km As a rule, with lower tilt angle , there is less ds: (diameter of sun = 1,39 . 106 km shading and the area can be better d: diameter of the obstacle, m. exploited. However, in that case, the solar yield drops throughout the year. For this The previous equation can be simplified to: reason, a tilt angle of 30° is usually chosen at Central European latitudes (Solarpath, 2011). Based on the height of the obstacle, a draft FIGURE 12. estimation of the minimum distance (Lmin) Lmin , BASED ON THE THICKNESS OF THE OBJECT so that the PV will not be shaded is presented to the following figure (FIGURE 11).
FIGURE 11. MINIMUM DISTANCE OF PVS NOT TO BE SHADED BY OBSTACLES
Self-shading of a PV array is usually a designer’s fault. The installer has to minimize shading losses through optimisation of the tilt angles and the distances between the module rows.
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An easy way to calculate the minimum Using the sextant measure the height of each distance between arrows is presented below obstacle, (Kirchensteiner, 2010). Step 4: It is recommended that the row spacing Note the height of each obstacle on the solar avoids shading between 09:00am and map, (FIGURE 11) 15:00pm at the Winter Solstice. At that date the sun is at its lowest angle (e.g. about 23⁰ Step 5: in Greece). The installer rotates 15⁰ degrees, with his back to the north, and repeats steps 5, 3 and 4 until he reaches west. FIGURE 13. MINIMUM DISTANCE BETWEEN ARROWS Step 6: The spots are connected on the solar map and the area under the line is shaded. A suitable area for a PV system should not be shaded between 09:00am and 15:00pm.
2.1.4. Array Orientation and Tilt Orientation of the PV array is one of the most important aspects of the site assessment. Most PV systems are mounted in a fixed position, and cannot follow the sun throughout the day. In that case, the optimal orientation in the northern hemisphere is due The minimum distance Lmin (FIGURE 13) is south. estimated by the following equation. The highest efficiency of a PV module is Lmin = (sina/tanβ+cosa) x L achieved when its surface is perpendicular to The estimation of whether a site is the sun’s rays. In the northern hemisphere, appropriate or not, may also performed with the sun rises to its greatest height at noon on the help of a solar map of the region the Summer Solstice and sinks to its lowest investigated, a compass, a sextant for angle at noon on the Winter Solstice. These measuring heights in degrees. elevations vary depending on location’s latitude. For this purpose the following steps should be followed: PVs should be tilted toward the sun’s average elevation, equal to the latitude of the array’s Step 1: location, to capture most of the solar energy Stand in the middle of the proposed field, throughout a year. Step 2: However, for off-grid systems designed to perform best in winter, the array should be Using the compass find the East direction, tilted at an angle of latitude (φ) + 15⁰. If the Step 3: array is designed to perform best in summer,
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then the array should be tilted at an angle of The most common mounting methods latitude (φ) − 15⁰ (TABLE 2). (NABCEP, 2009) are:
TABLE 2. a. Integrated mounting OPTIMUM TILT FOR THE PV PANEL (NORTH HEMISPHERE) (Source : Markvart & Castafier, 2003) The PVs are integrated to the building and β = φ Throughout the year are referred as BIPV (Building Integrated β = φ + Perform best in winter Photovoltaics, see chapter 3). BIPV are 15⁰ usually constructed along with the building β = φ - Perform best in summer elements, however they could be built later 15⁰ on in some cases. Integral mounting is where In humid climate areas, solar the modules are integrated into the roofing radiation is diffused in sky or exterior of the building itself. Three areas because of the water droplets in of the building where PV modules can easily β = φ - the atmosphere (the PV panel be integrated (FIGURE 14): 15⁰ faces the sky and larger diffuse - the roof, radiation amount arrives are - the façade, received) - the sun screening components. β = 5 - In areas with a latitude of less 10⁰ than 20o around the equator β = 0⁰ In areas with very little sunshine FIGURE 14. ALTERNATIVES FOR INTEGRATING PVs IN BUILDINGS (Source: in order to exploit diffuse PURE project. Roman et al, 2008) radiation
β = φ Throughout the year β = φ + Perform best in winter 15⁰
If the PV array is mounted on a building where it is difficult for the panels to face the South, then it can be oriented to the East or West but under no circumstances to the North as its efficiency will be then very limited (NCSC, 2001).
For better results, the installer may consult FIGURE 15. one of the software packages presented in PV PANELS FOR SUN SCREENING. (Source: ReSEL, TUC, 2010) chapter 2.3.
2.1.5. Μοunting Methods
Building Mounts
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solutions, as PV cells are more efficient at lower temperatures and when they are adequate ventilated; installer has to take provision for enough space on the back of the module. During the system design, the installer should take into account ways to reduce overheating, as much as possible. As a general rule, roof mounted systems should have at least 50mm free space beneath them (NABCEP, 2009).
In the case of stand-off mounted PVs, the air b. Rack mounting circulation behind the modules reduce the PV PV panels are based on a metal framework module operating temperature, making them allowing easy attachment and detachment of more efficient. the panels. In most cases, panels are FIGURE 17. mounted above and parallel to the roof PANELS MOUNTED ABOVE ROOF (Source: Flickr, Entersolar, surface. The rack mount is usually offered 2011) with the panel, by the PV manufacturer. FIGURE 16. PV MODULES IN INCLINED ROOF (Source: Flickr, Sun Switch, 2011)
Ground Mounts In rural environment, ground mounted PVs are met. Ground-mounted PV systems c. Stand-off mounting involve a steel or aluminum frame, fixed to The panels are supported by a frame built the ground on a concrete basis. The above the roof. The difference from the rack requirements of the frame are to provide a mount PVs is that the angles can be adjusted. rigid attachment that will resist gravitational Usually the PV panels aren't parallel to the waves, wind or impact forces. roof. In this case, fencing is often required to This type of mounting may not be protect the panels from vandalism. The aesthetically acceptable; however the PVs’ planning should take into account not to have efficiency is higher than the ones with rack shadings because of the fence. mounting. The advantage of the ground mounted panels Some types of building mounted PVs (e.g. is that they may easily oriented directly to solar tiles) are not as efficiently as other south, at the optimum tilt angle resulting to
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more efficient installations and maximum west axes. Power output, in this case is energy production throughout the year. approximately 40% increased compared to Panels are easier to maintain and replaced, if fixed array. However, the tracker’s moving required. parts require maintenance; potential failures, may decrease reliability and However, ground mounted panels are more increase maintenance costs. expensive than roof-mount because of the FIGURE 19. cost of concrete posts and rigid frames. TRACKING SYSTEM (Source: ReSEL, TUC) Furthermore, these systems suffer from visual pollution. Solar trackers are often used to improve the efficiency of this type of system.
FIGURE 18. G ROUND MOUNTED PV PANELS IN CRETE (Source: ReSEL, TUC)
2.1.6. BOS Locations Balance-of-system (BOS) is the auxiliary equipment which is related to supporting and security structures, inverters, disconnects and overcurrent devices, charge controllers, batteries, and junction boxes (NABCEP, 2009). PV arrays with trackers collect a higher Some of the components may need to be amount of energy than those installed at a installed in weather resistant or rain-tight fixed tilt. The relationship between the enclosures, if they are not rated for wet and annual solar radiation captured by a tracking outdoor exposure. The installer should system and a fixed tilt panel inclined at the estimate the dimensions of the required angle of latitude is increased by more than space to install all components during initial 30% in locations with predominantly clear sky planning; the environmental conditions (Markvart & Castafier, 2003). specified by the manufacturer should be also maintained. There are two types of tracking systems Considering the BOS location, the installer (Pearsall & Hill, 2001): should try to avoid sites exposed to direct - One axis tracking: The array can be tilted sunlight, strong winds and to choose a place automatically along a single axis from east protected from rain and moisture. If the to west. Output can be increased, system includes batteries, it is essential that approximately at 20%, compared to a fixed they are not exposed to extreme cold, which array. reduces their effective capacity. Moreover, the ideal installation site for inverters is cool, - Two axis tracking: The array can track the dry, dust free and close to the PV array, the sun along the north-south and the east- junction box and the batteries (if existing) in PVTRIN Training course- Solar installers handbook 21
order to minimize cable length and size (DGS, only be sized effectively for predictable loads; 2008). random load estimations may result in uncertain reliability of supply by the system. Average Average Annual rated usage energy The installer may also consult tables with power (h/day) consumption indicative consumption values for different (W) (kWh/year) Lighting appliances, following to the identification of customer’s energy needs. Bedroom 94 1 ,0 36 TABLE 3. Dining 165 2,3 136 VALUES OF TYPICAL ENERGY CONSUMPTION (Source: Markvart room & Castafier, 2003) Hall 78 1,7 49 2.1.8. Performance ratio Family 106 2,0 77 room During the on-site visit, the installer may be Kitchen 95 3,2 109 asked for an initial estimation of the system’s Living room 124 2,4 109 annual yield and the size of area required. Outdoor 110 2,9 116 An approximately estimation of the necessary Bathroom 138 1,9 96 surface is calculated as: 10m2 = 1 kWp; a draft Other Appliances estimation of the cost of a grid connected PV Refrigerator 649 system is 2.800-3.600 €/kWp. Freezer 46 5 A rough estimation for the production may Washing 0,375 4 78 be implemented using the Performance Ratio kWh/load machine loads (PR). PR expresses the performance of the per system in comparison to lossless system at week the same design and rating at the same Dish 0,78 One 283 location (reference yield), (Pearsall & Hill, kWh/load washer load 2001). per Typical PR values are 60-75% however higher day values can be achieved. Rough array sizing Electric 2.300 0,25 209 can be done using estimates of the PR as oven follows (SEAI 2010): Coffee 301 - Assumption of PR value: 0,7 (typical), machine Microwave 120 - Determination of the solar irradiation on the actual array. Vacuum 14 cleaner Audio 36 For example: 1.000 kWh/m2/y x 0,15 (module equipment efficiency) x 0,95 correction factor for tilt and TV 100 5 182 azimuth or 142,5 kWh/m2/y.
PC 25 - The output of the PV system, is estimated 2 2 2.1.7. Load Description as 0,7 x 142,5 kWh/m /y = 99,8 kWh/m /y. (SEAI, 2010). In case that a stand-alone system has to be Based on this value, the installer may also installed, a detailed documentation of the estimate the annual income of the loads is necessary. Autonomous systems can PVTRIN Training course- Solar installers handbook 22
2 DESIGN PRINCIPLES
installation, taking into account the national The point on the curve’s knee is where the electricity price/kWh. maximum power output is achieved. This is called maximum power point (MPP) and the
points describing this curve point are IMPP 2.2. System Sizing and Design (current at maximum power) and VMPP (voltage at maximum power point). 2.2.1. Basics The I-V characteristic curve is valid under standard conditions of sunlight and device I-V curve temperature. A current-voltage (I-V) curve presents the It is assumed that there is no shading on the applicable combinations of current and device. Standard sunlight conditions on a voltage output of a PV (FIGURE 20). clear day are assumed to be 1kW/m2 which is The PV module produces its maximum called peak sun. current when there is no resistance in the circuit. This maximum current is known as the Filling factor short circuit current (Isc). When the module is The filling factor FF informs of the extent to shorted, the voltage in the circuit is zero which a module deviates from the ideal (ANU, 2011). operation (FIGURE 20). It is the ratio of the The maximum voltage occurs when there is a MPP to the product of VOC and ISC. The filling factor for a good module is around 0,75. break in the circuit. This is called open circuit voltage (Voc). Under this condition the Effect of temperature resistance is infinitely high and there is no The operating temperature of PV cells is current. The range between these extreme determined by the ambient air temperature, conditions, are presented on the I-V curve. the characteristics of the encapsulation and the intensity of sunlight falling on the FIGURE 20. module, the wind and other variables. I-V CURVE OF A SOLAR CELL Temperature increase leads to a reduction in Voc, resulting to reduced cell output.
FIGURE 21. EFFECT OF TEMPERATURE ON I-V CURVE
The available power (W) from the PV, at any point of the curve, is the product of current and voltage at that point.
Interconnecting PV modules PVTRIN Training course- Solar installers handbook 23
PV modules can be interconnected in a series FIGURE 23. PARALLEL CONNECTION where the negative terminal of one module is connected to the positive terminal of the next module. In series connections voltage adds up
V total = V1 + V2+ ... + Vn and the current remains constant
Itotal = I1 = I2 = … = In
FIGURE 22. SERIES CONNECTION
For the modules connected in parallel (FIGURE 23)
Vtotal = 12V and Itotal = 3A+3A =6A A series and parallel connection of different modules can also be implemented (FIGURE 24). In this case Vtotal = V + V = 24V and I = I + I = 6A 1 2 total 1 2 FIGURE 24. The modules in FIGURE 22 have an open- SERIES AND PARALLEL CONNECTION circuit voltage of 12V each, and 2 modules adding to 24V.
V total = 12V + 12V=24V and Itotal = 3A In parallel connections the current adds up
I total = I1 + I2+ ... + In and the voltage remains constant
Vtotal = V1 = V2 = … = Vn In case that high current is demanded for specific applications, then modules are generally connected in parallel. 2.2.2. Inverters
The inverter converts DC voltage of the modules to the two-phase or three-phase AC voltage of the grid. The inverter usually has a Maximum Power Point Tracking (MPPT) where the PV operates at its highest efficiency. However, the voltage and current PVTRIN Training course- Solar installers handbook 24
2 DESIGN PRINCIPLES
generated by the PV modules must fit within FIGURE 25. PV MODULES CONNECTED TO INVERTER USING CENTRAL the inverter range. If PV modules are INVERTER connected in series, their voltage is added to give the total voltage, whereas the current of parallel PV modules is added to give the total current (Salas et al, 2009). Three inverter families, related to specific PV system designs, can be defined (Myrzik & Calais, 2003): central inverters, module integrated inverters and string inverters. a. Central inverters
Central inverters were the most commonly used in 1980’s for PV grid connected systems. However, several drawbacks observed in b. Module integrated inverters systems using them (risk of electrical arc in The smallest possible grid connected PV DC wiring, poor adaptability to customers’ system unit is a PV module with a module- requirements) leading to the introduction of integrated inverter so that, mismatching the modular system technology which was losses and DC wiring are minimized. more reliable and cheaper. However, this technology has also drawbacks In the low voltage concept (<120V) several concerning efficiency due to the low power modules are connected in series in a string. ratings involved. The cost per watt is also Since only a few modules are in series high. shading have less effect compared to longer FIGURE 26. strings. However, the reason that the concept PV MODULES CONNECTED TO INVERTERS USING MODULE is not commonly used is the high currents INVERTER and the resulting high ohmic losses that can be limited with the use of high cable sections (DTI, 2008). In high voltage concept (>120V) smaller cable sections can be used as a result of the lower currents however the high shading losses due to the long strings is an essential drawback. In master slave concept, one of the inverter is superior to the others and regulates operation of the rest in the chain. With increasing irradiance, the power limit of the c. String inverters master device is reached and the next The string inverter was introduced to the inverter (slave) is connected. When the market in the mid of 90’s and is a radiation levels are low, higher system compromise between module integrated and efficiencies are enabled compared to the case central inverter concepts. This type is the where all inverter are permanently operating most popular today. (Myrzik & Calais, 2003). The efficiency of string inverters ranges from 94-97%, so researchers focus on new PV PVTRIN Training course- Solar installers handbook 25
system concepts in order to increase efficiency and reduce costs of a PV plant. Maximum number of modules FIGURE 27. PV MODULES CONNECTED TO INVERTERS USING STRING At low temperatures, the module voltage INVERTER increases (FIGURE 21). The highest voltage is observed at open-circuit voltage at low temperatures. If the inverter is switched off on a sunny winter day it could lead to too high open-circuit voltage when it is switched on again that would damage the inverter. In order to avoid damages the highest voltage must be lower than the maximum DC input voltage at the inverter (DGS, 2008). So the maximum number of series-connected modules is given from the following equation:
Vmax(INV): maximum input voltage of the Sizing the inverter inverter, The nominal AC power of the inverter is the Voc-Tmin: open-circuit voltage of the module at power that the inverter can supply the minimum module temperature. continually at ambient temperature 25° ± 2°C. In most cases the value of Voc-Tmin, is not provided by the manufacturer. However, it The DC power rating of the inverter (PINV DC) can be calculated if the values of Voc at STC is approximately 5% higher than the (25⁰C) and the voltage temperature inverter's nominal AC power (DTI, 2008). coefficient TC are available then Voc-Tmin, is The power range can be specified for the given from the following equation: sizing range: Voc-Tmin = Voc -STC - ÄÔ x Tc 0,8 PPV < PINV DC < 1,2 PPV ÄÔ: difference between the minimum
PPV : the PV array power rating in Wp ambient temperature and the temperature of 25⁰C (STC). The relationship between the installed power of the PV generator and the maximum TC: voltage temperature coefficient in V/⁰C, inverter power is known as inverter sizing that means that for every ⁰C, the factor CINV and can be calculated from the temperature of the module drops below following equation (Velasco et al, 2006): 25⁰C, the module voltage will drop by this value.
PINV AC: the inverter’s nominal AC power. Minimum number of modules
A typical value of CINV would be in the range On the contrary the maximum temperature 0,83 < CINV < 1,25, but it seems to be cost reached on a PV panel is used in order to effective for CINV <1.
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determine the minimum number of modules Imax INV: maximum permitted DC input current in a string. of the inverter
During a sunny day of summer the PV has a In string: maximum string current. lower voltage than at 25 oC (STC) because of the increased temperatures. In case that the operating voltage of the system drops below 2.2.4. Sizing of cables the minimum MPP voltage of the inverter, it would not feed the maximum possible power Three crucial parameters have to be taken and, and it could even be possible to switch into account when sizing the cables: itself off. - cable voltage ratings, - current rating of the cable, This is the reason that the system should be - minimizing of cable losses. sized as to the minimum number of series- connected modules in a string is derived from the following equation: Voltage ratings Voltage ratings of cables are in general greater than the PV systems’, however in large systems the voltage rating must be VMPP (INV-min): minimum input voltage of the checked taking into account the maximum inverter at the MPP open-circuit voltage at the lowest temperature of the PV array. VMPP- Tmax: voltage of the module at the MPP at the highest temperature. The cable cross section is sized according the maximum current. The maximum current of The VMPP at different temperature can be the module or string cable is given by the calculated when the V MPP-STC is given from the following equation: following equation:
Imax = ISC PV - ISC String VMPP-T = VMPP-STC - ÄÔ x Tc
ISC PV : PV generator short-circuit current So if for example V MPP-STC = 40V (using the values from the previous example) then ISC String: the short-circuit current of one string ÄÔ= 75 oC - 25 oC = 50 oC o o o VMPP-75 C = 40 - 50 C x (-0,155V/ C) = 49,75V String fuses String fuses can be used to protect cables from overloading and are usually used for 2.2.3. Number of strings systems with more than four strings. The maximum PV array current must not The permitted current rating of the cable exceed the maximum inverter input current. should be at least equal or greater than the The maximum number of strings can be thus trigger current of the string fuse. estimated from the following equation (DGS, 2008): Iz Cable ≥ Ia String fuse The fuse has to be triggered at twice the string short-circuit current at STC:
2 ISC String > In String fuse > ISC String PVTRIN Training course- Solar installers handbook 27
In order to avoid false trips, The value then is rounded up to the next highest value for standard cable cross I ≥ 1,25 I n String fuse n String sections. I : nominal current of the fuse, A n String fuse Next equation is used to calculate the overall In String: nominal string current, A losses (W) in all modules and string cables for the selected cable cross-section.
Minimizing cable losses
One of the main targets when sizing the cable cross sections takes into consideration the n: number of strings of the PV generator need for as little cable loss/voltage drop as In case, that the PV systems lead to different possible. string cable lengths the equation used is: It is recommended that the voltage drop in the direct voltage circuit should be less than 1% of the nominal voltage of the PV system The DC main cable and the DC bus cables at STC in order to limit the loss power from PV sub-arrays must be able to carry the through all DC cables to 1% at STC. For PV maximum occurring current produced by the systems with inverters operating with a PV array. The DC main cable is in general higher DC input voltage (V > 120V) 1% MPP sized to 1,25 times the PV array short-circuit losses can be maintained with standard cable current at STC cross-sections. (DGS, 2008) I = 1,25 I However, PV systems with inverters max SC PV operating with a higher DC input voltage less The cross section of the cable must be than 120V the voltage drop with the string or selected according to the permitted current module cable exceeds 1%, even when using a carrying capacity of the cable. It is again 6mm2 cable, particularly when the distances assumed that there will be a cable loss of 1 % between the inverter and the PV generator is in relation to the nominal power of the PV long. In these systems a 1% voltage drop in array. the string cables and an additional 1% per The cross section of the DC cable is given cent drop with the DC main cable are from: acceptable. The cross section with the 1% losses (at STC) recommendation can be selected then using the following equation LDC cable: simple wiring length for module and string cabling, m
In: nominal current of the PV module, A
Lm: simple wiring length for module and PPV: nominal power of the PV module, Wp string cabling, m PM: line loss of the DC main cable, W IST: string current, A ê: electrical conductivity, m/Ω mm2 VMPP: string voltage, V í: loss factor í = 1 %, or í = 2 % with the low ê: electrical conductivity, m/Ω mm2 (copper voltage concept. êcu = 56, aluminium êal = 34) PVTRIN Training course- Solar installers handbook 28
2 DESIGN PRINCIPLES
The value then is rounded up to the next 2.2.5. Blocking Diodes highest value for standard cable cross sections. Blocking diodes are used in PV arrays to prevent reverse currents (Markvart & Next equation is used to calculate the overall Castafier, 2003). losses in all modules and string cables for the selected cable cross-section. Blocking diodes when placed at the head of separate series wired strings in high voltage systems can isolate shaded or damaged string and prevent the other strings from loosing The calculation of the cross section of the AC current backwards if there is a short circuit in connection cable is made assuming a voltage one of the modules. drop of 3% relative to the nominal grid Furthermore, in battery charging systems, the voltage. The cross section AAC cable is then blocking diodes can block reverse flow of estimated from the following equation: current from the battery through the module at night. As the module potential drops to zero during night, the battery could discharge
all night backwards through the module. This with a single-phase feed would not be harmful to the module resulting
LAC cable: simple line length of the AC connect to the loss of the energy stored in the battery ion cable, m bank. When diodes are placed in the circuit between the module and the battery they I : AC nominal current of the inverter, A n AC block any leakage flow at night. cosö: power factor (between 0,8 and 1,0) 2.2.6. Earthing Vn: nominal grid voltage, single phase: 230V Earthling is the procedure where one or more
parts of an electrical system are connected to In case of three-phase feed: earth, which is considered to have zero voltage (Markvart & Castafier, 2003).
Earthing procedures may vary depending on the different local codes. An equipment- V : nominal grid voltage, three phase: 400V n grounding conductor is a conductor that does not normally carry current and is connected to earth. This type is used to connect the The cable loss PAC c able for the selected cable cross section, is then estimated: exposed metal surfaces of electrical equipment together and then to ground. In order to prevent electrical shocks and allow overcurrent devices to operate properly in single-phase feed, and when ground faults occur. PV systems should have equipment- grounding conductors that connect all of the exposed metal surfaces of the system to a in three-phase feed. grounding electrode (the metallic device used to make actual contact with earth).
PVTRIN Training course- Solar installers handbook 29
However grounded conductors have to be FIGURE 28. EXAMPLES OF PROTECTION (Source: IEA PVPS, 2003) used only for systems with a system voltage over 50V. In this case the voltage should be calculated for low temperatures as the open- circuit voltage will be higher than the open- circuit voltage marked on the back of the PV module at STC (Wiles, 1999). A nominal 24V system has a rated open- circuit voltage of about 44V at 25°C. That means that in temperatures below zero the voltage could exceed 50V (see § Maximum number of modules) and current-carrying conductors should be connected to the grounding electrode.
2.2.7. Lightning protection The Protective Earthing (PE) conductor can In case that the PV system is located outside discharge the DC conductors in case of a the protection zone of a building, a direct strike; so damages to the low voltage protection device is needed to shelter it grid or to the inverters may be limited. against lightning strikes (FIGURE 28). Wiring usually runs on the outside of a The system can be damaged even if the building from the roof to the power grid. In lightning does not hit it straight. Protection this case both the PE and the DC wires have against the lightning can be achieved through to be exposed outside. several measures: For small PV plants on buildings with lightning - se of a single ground electrode, protection, the plant may be entirely - connect all the metallic parts of the electric protected by the existing lightning system. To equipment ground, achieve this, all parts of the PV generator - arrange of the cables to avoid loops that have to be located in the mesh of the can produce over-voltage generation, lightning protection system. The mesh - Install of lightning protectors connected to consists of a ridge wire and two wires on the protected equipment ground (IEA PVPS, each side (FIGURE 29). 2003).
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FIGURE 29. TABLE 4. SMALL PV IN LIGHTNING SYSTEM MESH. (Source: Schletter APPLIANCE CLASSES. (Source: IEC, 2011) Solar, 2005). Class I Class II Class III Appliances have Appliance has Designed to be their chassis been designed supplied from a connected to that a safety separated or electrical earth by connection to safety extra-low earth conductor electrical earth is voltage power (green/yellow). not required. The source so that Fault in the basic requirement the voltage appliance causes is that no single supply is low a live conductor failure can result enough that to contact the in dangerous under normal casing and current voltage becoming conditions a to flow in the exposed so that it person can earth conductor might cause an safely come and trip either an electric shock and into contact overcurrent that this is with it without device or a achieved without risk of electrical residual current relying on an shock. circuit breaker earthed metal which cuts off the casing. This is A safety distance, between the PV plant and supply of achieved by all parts of the lightning protection system, electricity to the having two layers has to be kept. In practice, distance of more appliance. of insulating material than 0,5m is proven adequate (FIGURE 29). surrounding live parts or by using For large PV systems, the minimum distances reinforced between plant and lightning protection often insulation. cannot be kept. The plant may not cover If the minimum distance (>0,5m) cannot be existing lightning protection conductors kept, the PV generator and the lightning otherwise surge currents could get into the protection system are connected in order the building over the generator, in case of a consequences of sparkovers are limited. The lightning strike, and to cause severe damages connection (Cu) should at least have a cross- (FIGURE 30). section of 16mm2.
In this case: FIGURE 30. - Lightning protection connections are LARGE PV SYSTEM ON ROOF. (Source: Schletter Solar, 2005). possibly left out, respectively replaced by High Voltage Insulated (HVI) conductors so that minimum distances are kept. - Additional connections and arresting devices protect building and plant (Schletter Solar, 2005).
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In this case, it would be better to have a TABLE 5. PENETRATION DEPTH BY LIGHTNING PROTECTION CLASS connection between the mounting frame and ACCORDING TO VDE 0185-305. (Source: OBO-Betterman, the potential equalisation of the house. If 2010) such a connection is built, it should also have Distance of Penetration depth Lightning a cross-section of a least 16mm2 Cu. interception protection (Schletter Solar, 2005). system (d) class I class II class IIÉ in m Lightning protection sphere: R = The rolling sphere (FIGURE 31) is a method of 20 m 30 m 45 m 2 0,03 0,02 0,01 testing the protection areas against a direct lightning strike. A sphere is rolled over a 3 006 0,04 0,03 model of the system and all the contact 4 0,10 0,07 0,04 points represent possible points for direct 5 0,16 0,10 0,07 lightning strikes (OBO-Betterman, 2010). 10 0,64 0,42 0,28 15 1,46 0,96 0,63
20 2,68 1,72 1,13 FIGURE 31. ROLLING SPHERE METHOD. ( Source: OBO-Betterman, 2010)
2.2.8. Stand-alone PV system sizing Sizing Stand-alone PV array The equation that may be used to size a stand-alone PV system (Antony et al, 2007) is:
WPV: peak wattage of the array, Wp Å: daily energy requirement, Wh G: average daily number of Peak Sun Hours (PSH) in the design month for the
inclination and orientation of the PV array When several interception rods are used to protect the panels the penetration depth nsys : total system efficiency. between them must also be taken into account (TABLE 5). The total system efficiency can be calculated as follows:
nsys = nPV x nPV BAT x nCC x nBAT x nDIST x nINV
nPV : module’s efficiency,
nPV BAT: losses due to voltage drop in cables from PV array to battery,
nCC : losses in a charge controller,
nBAT: battery losses,
nDIST: losses in distribution cables from PV battery to loads, PVTRIN Training course- Solar installers handbook 32
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nINV : losses in inverter, radiation in a horizontal plane, then a tilt and orientation correction factor should be The module’s efficiency can be estimated applied. from the following equation:
nPV= nSTC x fa x fd x ft x fdio Batteries Stand-alone PV systems use battery backup. n : module’s efficiency at STC, STC The most common type is lead-acid batteries, fa: de-rating aging factor, as they are cheap, reliable and have relatively good energy storage density. Lead battery fd: de-rating factor for dirt/soiling, cells consist of two lead plates immersed in ft: temperature de-rating factor, dilute sulphuric acid which creates a voltage fdio: de-rating diode factor, of about 2V between the plates. Cells are then connected in series to have 12V Indicative values for previous magnitudes are batteries. presented in TABLE 6. The ideal charging cycle of a battery includes the following stages: TABLE 6. INDICATIVE VALUES (Source: Antony, 2007) - the battery is charged at constant current Factors Indicative values until the voltage reaches a predefined 2% cabling losses from the PV to battery thus, value, n PV BAT 0,98 - the voltage is held constant while the 2% losses in a good quality charge controller charging current decays, nCC thus, 0,98 - after suitable time the charging voltage is nBAT 10% battery losses thus, 0,90 reduced to avoid excessive gassing and loss
nDIST 2% cabling losses thus, 0,98 of electrolyte. 10% losses in a good quality inverter thus, n INV 0,90 However, the ideal charging cannot be
nSTC 0,12-0,14 for Poly-Si PV panels achieved to a PV system where the available The reduction of efficiency is about 1% per power is constantly changing. f a year, thus after 5 years f a =0,95 0,95 for panels regularly cleaned In stand-alone systems, the cycle of the 0,90 for panels lightly dusted battery is within 24 hours, charging during f d 0,80 for horizontal dirty panels daytime and discharging at night. Typical Indicative value 0,88 . daily discharge may range from 2 -20% of the f t = 1- [(T a +TPV)-25] 0,004 o f t Ta: mean monthly ambient temperature, C battery capacity. T : temperature on the PV panel , oC PV When designing the PV system potential f dio 1% losses from the blocking diodes, thus 0,99 problems such as sulphation, stratification and freezing should be taken into account in The month that the system is designed is the order to be avoided (Markvart & Castafier month of the lowest average daily solar 2003). radiation during the operational period of the - Sulphation occurs if the battery is system (December if the system is used discharged if the voltage falls below the throughout the year). discharge cut-out voltage (deep discharge), The number of peak hours is for the and the acid concentration undergoes a inclination and orientation of the PV array. If strong reduction. the only information available is for solar PVTRIN Training course- Solar installers handbook 33
- Stratification occurs when acid forms layers of different density on cycling. Batteries that are regularly deep discharged and then Q: minimum battery capacity required, Ah fully recharged, concentrate lower density acid at the bottom; while batteries with E: daily energy requirement, Wh regular shallow cycling which are not 100% A: number of days of storage required recharged concentrate lower density acid at the top. V: system DC voltage, V - Freezing in lead-acid battery occurs as the T: maximum allowed DOD of the battery battery is discharged; the acid becomes usually on battery data sheet (indicatively 0,3 more ‘watery’ and the freezing point is -0,9) raised which can cause severe problems if ninv: inverter efficiency (1,0 if there’s no the battery is operating in sub-zero inverter) temperatures. n : efficiency of the cables delivering the Very good lead acid batteries may work for cable power from battery to loads. up to 4.500 cycles at 30% depth of discharge (DOD) which is equivalent to 20 years lifetime Diodes (Kirchensteiner, 2011). Blocking diodes protect the battery from Batteries are generally installed in an short circuits, and also prevent from insulated enclosure, separated from controls discharging through the modules when there or other PV system components which may is no light. Diode voltage droppers can also have cooling/heating mechanisms in order to be used to ensure that the batteries will not protect them from excessive temperatures. supply excess voltages to the load (Wenham The enclosure should be designed to limit et al, 2007). direct exposure to sunlight. When temperature swings are reduced, battery will have a better performance, longer life, and Charge controllers lower maintenance (Dunlop, 1997). Charge controllers, are required in stand- The nominal capacity of the battery is given alone systems to protect batteries against from the following equation (Markvart & limiting discharge and overcharge levels. Castafier, 2003): Main characteristics (FIGURE 32) of the . Qn = In tn control charger (Wenham et al, 2007) are:
In: constant discharge current, A - Regulation set point (VR): maximum allowable voltage. The control charger will Cn: discharge time, h either interrupt charging or regulate the current delivered to the battery when reaching this point (Dunlop, 1997). Battery sizing - Regulation hysteresis (VRH): the difference The battery has to store energy for many between VR and the array reconnect days and used without going over the voltage. If the hysteresis is set too high, DODmax (Antony et al, 2007). there will be long interruptions to charging. The following equation can be used: If VRH is set too small the array will cycle on and off rapidly. The voltage level VR – VRH is called VRR. PVTRIN Training course- Solar installers handbook 34
2 DESIGN PRINCIPLES
- Low voltage load disconnect set point (LVD): There are two main charging regulation defines the voltage at which the load is methods (Wenham et al, 2007): disconnected preventing over-discharging a) Interrupting (on/off) regulation. The (DODmax). Over-discharging the battery can controller leads all available PV current to the make it susceptible to freezing and shorten battery during charging. On reaching the it’s operating life maximum allowable voltage, the controller - Load Reconnect Voltage (LRV) Set Point: switches off the charging current. When the The battery voltage at which a controller voltage falls to VR – VRH, the current is allows the load to be reconnected to the reconnected. battery. Once the controller disconnects the load from the battery at the LVD set point, b) Constant voltage regulation. The controller the battery voltage rises to the open-circuit can modify the VR set-point by sensing the voltage. When additional charge is provided battery condition or using a low VR in order by the array, the battery voltage raises to avoid excessive gassing, coupled with more and as soon as the battery voltage provision for an occasional gassing and state of charge are high enough it ‘equalisation’ charge. reconnects to the load. The two charging regulation may be applied - Low voltage disconnect hysteresis (LVDH)— via shunt or series arrangements. the voltage span between the LVD and the The shunt (parallel) regulator has a switch load reconnect voltage. If LVDH is set too that is open when the battery is charging and small, the load cycles on and off rapidly at closes when the battery is fully charged. low battery state of charge, possibly damaging the load or controller, and The series regulators are connected in series extending the time it takes to fully charge between module and battery. These the battery. If set too high, the load may regulators are usually simple and cheap. remain off for an extended period until the array fully recharges the battery. FIGURE 33. SHUNT CHARGE CONTROLLER (Source: DGS LV, 2008)
FIGURE 32. CHARGE CONTROLLER SET POINTS (Source: Dunlop, 1997)
To limit the charging current, the regulator adjusts the transistor resistance according to the battery voltage. Series regulators are mainly used in small systems (Kirchensteiner, 2010).
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FIGURE 34. - system voltage, SERIES CHARGE CONTROLLER (Source: DGS LV, 2008) - PV array and load currents, - battery type and size, - environmental operating conditions, - mechanical design and packaging, - overcurrent, disconnects and surge protection devices, - costs, warranty and availability (Wenham et al, 2007).
The Maximum Power Point Regulator Charge controllers should be sized according The MPP regulator searches for the best to the voltages and currents expected during operating point of a module and ensures that operation of the PV system. the module delivers the maximum possible The controller should be able to handle power under all conditions. typical voltages and currents, but also peak The MPP regulator samples the output of a conditions from the PV array. cell and applies a resistance (load) to obtain It is preferable, regarding cost, to oversize maximum power for any environmental the controller as if it fails during operation conditions. The procedure defines the the costs of servicing and replacing several current which the inverter should draw from elements of the system will be significantly the PV, in order to get the maximum power higher. possible. Under certain circumstances, the maximum power current measured at STC could be Stand-alone inverters much higher and the peak array current could be 1,4 times of the nominal peak rated value. In a PV stand-alone system, the storage is Thus the peak array current ratings for charge realised by the batteries and the operation of controllers should be sized for about 140% or several loads using DC. Stand-alone inverters the nominal peak maximum power current enable the use conventional loads of 230V ratings for the modules or array. AC, on a DC system. The total current from an array is calculated Three inverter types are available: the by the number of modules or strings in rectangular, the trapeze and the sinus parallel, multiplied by the module current. It inverter (Kirchensteiner, 2010). is better to use the short-circuit current (Isc) The following requirements may be made of instead of the maximum power current (IMPP) a stand-alone inverter (Daniel et al, 2009): so that the shunt type controllers which operate the array at short-circuit current - very good conversion efficiency, even in conditions are safe. partial load range, - high overload capability for switch-on and The followings should be taken into starting sequences, consideration during the selection procedure of an inverter: - tolerance against battery voltage fluctuations, PVTRIN Training course- Solar installers handbook 36
2 DESIGN PRINCIPLES
- economical standby state with automatic The conductors used to wire the PV array load detection, come into the combiner box where they are - protection against short-circuit damage on connected via a power distribution block to the output side, larger ones that run to the charge controller and batteries. The purpose is to carry the - surge voltage protection, electrical energy from the PVs to the - bi-directional operation so that batteries batteries with a minimum of voltage drop. A can be charged from AC generators, if combiner box also permits the combining of necessary. multiple PV source circuits (sub-arrays, panels, or series strings) into a single DC source, and provides a method of removing a Cable selection and sizing module or sub-array from the array without Cables used for homes are always made of interrupting the rest of the system. It also copper. The requirements that should be allows for safe operation of the system in fulfilled for a module wiring are temperature case that a problem with a source circuit resistance, UV resistance, resistant to leads to high current. moisture, flexible and easy to work with and size for low voltage drop. To summarize the basic steps that the technician should follow in order to install a Every cable has a voltage drop on it. This is a PV system are presented in FIGURE 35 and problem in stand-alone systems because the FIGURE 36. batteries may not be properly charged because of the resistance RC (ohms). As cable resistance increases the more voltage drop FIGURE 35. raises following this formula: DESIGN OF AN AUTONOMOUS SYSTEM
ÄV =I x RC Estimation of the loads ÄV: voltage drop, V and appliances and of the daily energy I: current in the cable, A requirements Module sizing RC: resistance of the cable (Ù), which depends on the cable length and the cross- section. Sizing the battery
Basic formula for calculating cross-section: Choose optimum inverter
Select the P: consumer power, W appropriate wiring 2 AM: cross-section, mm L: cable length, m κ: electrical conductivity, m/Ω mm2
FIGURE 36. Combiner Box DESIGN OF A GRID CONNECTED SYSTEM PVTRIN Training course- Solar installers handbook 37
However, these barriers may be easily Estimate roof overcome if the installer is informed about
size needed for the permitting procedures, the grid the selected Check if the module fit the connection rules and technical standards, the roof grid connection procedures and grid capacity issues. Regulations vary in EU MS. Some Check the module information on this issue is presented in voltage chapter 2.5.
Module configuration Array configuration 2.3. Simulation software
There is a great variety of software tools for Check inverter’s compatibility sizing and simulation of performance of grid- connected and stand-alone PV systems. Some
of them are very complicated; others are user friendly, others may lack in accuracy or reliability. The installer is advised to access 2.2.9. Legal Aspects the results for their consistency. Administrative permitting procedures can be Indicative software solutions regarding PV a barrier for the implementation of a PV analysis and planning and site analysis, are system. These procedures may involve briefly presented in this chapter (TABLE 7). obtaining building permits, environmental TABLE 7. impact assessments, grid connection licenses, PV SIMULATION TOOLS electricity production licenses etc. PV analysis and planning The technician should be aware of the PV*SOL http://valentin-software.com PV F-CHART www.fchart.com required procedure and permits in order to PVSYST www.pvsyst.com be consistent to the terms of the Planning PV-DesignPro www.mauisolarsoftware.com authorities or the Regulatory Energy PVPlanner http://solargis.info/doc/4) Nsol!-GT www.nsolpv.com Authorities. Solar Pro www.lapsys.co.jp/english For example, the installer should be aware if /products/pro.html RETScreen www.retscreen.net a building is a listed one as in some cases PVs PVGIS http://re.jrc.ec.europa.eu/ cannot be applied on buildings which are pvgis/apps4/pvest.php designated as architectural, historical or Solar Sizer www.solarray.com PVselect www.pvselect.com cultural monuments; therefore specific Performance http://www.volker- permission should be issued by the Calculation quaschning.de/software/ competent authority. In addition, BIPVs may pvertrag/index_e.ph Educational ¡Error! Referencia de hipervínculo no subject to complicated planning procedures Sun applets válida. in some EU Member States. Furthermore, in Site Analysis most EU countries, the access to the low ECOTECT http://usa.autodesk.com/adsk/ servlet/pc/index?siteID=123112&id voltage grid has not yet been regulated and =12602821 procedures for the grid-connection have to Shadows http://www.shadowspro.com/ be implemented. Shade Analysis www.honeybeesolar.com/shade.html
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2.3.1. PV analysis and planning PV F-CHART (http://www.fchart.com) software The program provides monthly-average performance estimations for each hour of the PV*SOL (http://valentin-software.com) day to calculate the long-term average PV*SOL consists a multi-product software performance of utility interface systems, suite appropriate for the design, simulation battery storage systems, systems with no and financial analysis of PV systems, from interface or battery storage. Each system is small off-grid residential systems to large described using two sets of parameters commercial grid-connected and utility-scale (system and economics). The system set systems. The calculations are based on an contains the parameters describing the hourly data balance and the results may be optical, thermal and electrical performance presented in graphic form, in a detailed of the system. PV F-Chart contains weather project report or in a results summary. The data for over 300 locations, hourly load PV*SOL products are one of the most widely power demand profiles for each month, used. statistical load variation, buy/sell cost differences, time-of-day rates for buy/sell, PV*SOL programs include: and life-cycle economics. - PV*SOL basic,for the design of PVs<300kW, FIGURE 38. - PV*SOL Pro, for the analysis of INPUT DATA EXAMPLE ON DEMO VERSION OF PV F-CHART PVs<100MW, - PV*SOL Expert, containing all the capabilities of PV*SOL Pro plus the added capability of 3D array design and detailed shade analysis. A demo may be downloaded from the relevant website. An on line easy-to-use tool is also available for draft estimations.
FIGURE 37. ON LINE PV*SOL TOOL
FIGURE 39. OUTPUT OF EXAMPLE ON DEMO VERSION OF PV F-CHART (BASED IN FIGURE 38)
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PVSYST (www.pvsyst.com) Nsol!-GT (www.nsolpv.com) This software is suitable for grid-connected, Nsol!-GT is a sizing software, specifically stand-alone and DC-grid systems, and offers optimised for grid-tied PV systems. It includes extensive meteorological and PV-components databases for solar resource, PV modules, database. It offers 3 levels of PV system and grid-tied PV inverters. The software study, corresponding to the different stages allows rapid and accurate system design and of the development of a real project: performance analysis. It also includes a basic economic payback analysis, including value i) Preliminary design: system yield for system rebates, tax credit and production evaluations are performed using few credits. parameters. Nsol! V.4.6 includes modules for standalone ii) Project Design: aiming to perform a PVs, PV-generator hybrids and grid-tied PV. thorough system design using detailed hourly The standalone version includes the “Loss-Of- simulations. Load-Probability” statistical analysis. A demo iii) Measured data analysis: the import of version is available for download. measured data is allowed to display tables of FIGURE 40. the actual performances, and perform close EXAMPLE FOR ATHENS ON DEMO VERSION NSOL. comparisons with the simulated variables. An evaluation mode is available and may be downloaded for a monthly trial use, free of charge.
PV-DesignPro (www.mauisolarsoftware.com) The PV-DesignPro has been designed to simulate PV energy system’s operation on an hourly basis for a year, based on the user’s selected climate and system design. There are three versions of the PV-DesignPro program “PV-DesignPro-S” for standalone systems with battery storage, “PV-DesignPro- G” for grid-connected systems with no Solar Pro battery storage, and “PV-DesignPro-P” for water pumping systems. www.lapsys.co.jp/english/products/pro.html Solar Pro develops and supports virtual simulations for PV systems, allowing one to PVPlanner (http://solargis.info/doc/4) compute solar power over module arrays. It It is used for planning and optimization of PV also performs shade analysis and includes the systems using climate and geographic data shade influence to the sizing process in order and new generation algorithms. The software to check optimal settings and module can estimate PV electricity potential (in daily designs. The software calculates the amount or monthly basis), PV conversion losses and of generated electricity based on the performance ratio. latitudes, longitudes and the weather conditions of the installation site. The
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calculated data are presented in graphical PVselect (www.pvselect.com), a tool for form so they can be used for reports and pairing and comparing PV Modules and sales presentations of the PV system. inverters. Performance Calculation for Grid-connected PV Systems (www.volker-quaschning.de/ RETScreen (www.retscreen.net) software/pvertrag/index_e.php). The RETScreen Software - Photovoltaic Power Educational Sun applets Model is used to evaluate energy production and savings, costs, emission reductions, (http://users.cecs.anu.edu.au/ financial viability and risk for central-grid, ~Andres.Cuevas/Sun/Sun.html), enables the autonomous and grid connected PV systems. draft design of a PV panel by providing as input the locations’ latitude and monthly RETScreen models a wide variety of projects, irradiation data, as well as PV panels’ from large scale multi-array central power characteristics. The model produces the plants to distributed power systems located monthly energy produced. on commercial buildings and houses, or stand-alone battery storage systems for FIGURE 41. ON LINE TOOL FROM THE AUSTRALIAN NATIONAL UNIVERSITY lighting. The software is available in multiple languages and includes project and climate databases for free downloads.
PVGIS http://re.jrc.ec.europa.eu/pvgis/apps4/pves t.php The PV Geographical Information System is an information service of the European Commission, Institute for Environment and Sustainability. This is a research, demonstration and policy-support instrument for geographical assessment of solar energy Several other energy simulation software resources. It provides a map-based inventory packages like TRNSYS and EnergyPlus have of solar energy resource and assessment of extensive modules for detailed PV systems the electricity generation from PV systems in simulations. Europe, Africa, and South-West Asia. It is a free online easy-to-use tool. 2.3.2. Software tools for site analysis ECOTECT Apart from the above, there are available Ecotec performs an entire building energy numerous others online free tools; some analysis in 3D. Furthermore, sun’s position examples follow: and path as well as the solar radiation on windows and surfaces, over any period of the Solar Sizer (www.solarray.com) adds up the year may be estimated and visualized. electrical requirements of predefined FIGURE 42. appliances and assists the selection of BIPV VISUALIZATION ON EXISTING BULDING IN CHANIA USING appropriate components, such as PV ECOTECT (Source: Papantoniou and Tsoutsos, 2008) modules, inverters, controllers and batteries. PVTRIN Training course- Solar installers handbook 41
FIGURE 43. PV MODULE PRICE EXPERIENCE CURVE (US$/Wp & MW) (Source: EPIA, 2011)
Shadows Shadows is a useful program for solar energy engineering and assists to design sundials and astrolabes. It simulates, display, and animate, the shadow of different objects in different locations. Due to the economies of scale, a significant decrease in manufacturing costs and retail Shade Analysis, a tool to estimate shading prices of PV modules and systems has been losses for panels in different locations, was realised. orientations, tilts and slopes. The price of inverters is also reducing the last www.honeybeesolar.com/shade.html. years, following to the trend of the PV For further details on the above simulation modules. Several years ago the share of the software, the installer may visit the relevant panels in the total system cost was 60-75% website and/or to contact the supplier or the and now is estimated as 40-60%, depending software developer indicated in the on the technology. software’s references. Recently many governments have provided 2.4. Economics and Environmental capital grants or FITs to encourage people to install domestic PVs. Issues TABLE 8. SHARES IN THE TOTAL SYSTEM PRICE (Source: EPIA 2011)
2.4.1. Economic Aspects PV modules 40-60%,
Market of PVs Inverter 10% Engineering and procurement 7% The high cost of power from PV panels has been a major obstacle for the technology’s market penetration. However, today, it is Especially Germany and Spain have given a encouraging that there is a constant significant boost to the PV market, reduction in costs year by year (Lynn, 2010). introducing FITs which provide an additional PV modules price is reduced by 22% each push to the “learning curve”. As the time the cumulative installed capacity (in cumulative world production raises and the MW) is doubled (FIGURE 43). price comes down, less developed “sunny”
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countries are more likely to install domestic a. Determine the energy load required in PV systems. Wh/d. Multiply the number of W the load will consume by the hrs/day the load will operate The advantage of small domestic systems is (see also TABLE 3 in Chapter 2.1.7). Multiply that the power is generated on-site, and the result by 1.5. losses through transmission and distribution are limited. On-site generation can be an Total Wh per day required: __ Wh essential financial advantage that is often b. Determine the hr/day of available sunlight overlooked in cost analysis. at the site. However, the PV systems’ cost need to be Total available sunlight: ___hrs/day further reduced in order to be competitive to conventional sources of electricity. According c. Determine the PV array size. Divide the to the European Photovoltaic Industry energy demand (1.a.) by the number of Association (EPIA, 2011) this may be available sun hours per day (1.b.) achieved through: technological innovation, Total array size required: ___W production optimisation, economies of scale, increased performance ratio of PV, extended d. Determine the size of the battery storage lifetime of PV systems, development of (if battery is required). Multiply the load (1.a.) standards and specifications. by 5 (result is Wh). Then divide by the battery voltage (eg, 12 volts) to get the Ah rating of Estimating the cost of PV Systems the battery capacity. When investing in a PV system, it is helpful to Total battery capacity required: ___Ah start by estimating the expected cash flows over the lifetime of the system (20-25 years). Step 2. Calculate the cost of the PV system needed for this application: The initial capital cost can be considered the largest share of the expenditures of a PV Multiply the size of the array (1.c.) by 3.5 € system’s negative cash flow. per watt. This value is affected by many factors (eg: Cost estimate for PV array: € ___ cost of natural building, plant engineering, b. If a battery is used, multiply the size of the integration, bureaucratic, etc.); the designer battery bank (1.d.) by 0,7€ per amp hour. of the system has to perform an analytic assessment in order to provide a precise Cost estimate for battery bank: € ___ value. c. If an inverter is used, multiply the size of For a rough estimation, an average value is the array (1.c.) by 0,7€ per rated watt. around 3.000 €/kWp. This value should take Cost estimate for inverter: €____ into consideration the cost of replacing the Subtotal: € ___ inverter which has an average lifetime of 12- 15 years; its cost is approximately 5-8% of the d. Multiply the subtotal above by 0,2 (20%) to plant’s value. cover BOS costs (wire, fuses, switches, etc.). The installer may estimate the cost of a PV Cost Estimate for BOS: €____ system following the next steps (Infinite Total estimated PV system cost: € ______Power, 2009): (2a+2b+2c+2d) Step 1. Determination of the load, available sunlight, array size, battery size: PVTRIN Training course- Solar installers handbook 43
A number of free, on-line tools, such as “PV Eg. in case of 5% interest rate, 1€ today will payback” (Sunearthtools.com, 2011): and worth 1,05€ in 1 year ( ). “Solar Energy” from the Energy Bible.com (Energybible, 2011) allow estimations of the payback period in relation to the selling price If a project costs 1.000€ to set up and (€/kWh). Most of the software presented in generates cash flows of 100€, 500€ and chapter 2.3 allow more precise estimations 1.500€ in years 1-3, the hurdle rate which this based on detailed input data. project should earn in order to create value is calculated as : FIGURE 44. ESTIMATING THE COST OF PV SYSTEMS
In this case, i = 32,8% So the IRR may be defined as the hurdle rate for which the present value of a project’s cash flows equals zero. Any project should have an expected return greater than the IRR, in order to be worthwhile (Hopkins, 2009).
2.4.2. Environmental Issues
Energy payback time (EPBT) The EPBT is the time in which the energy input during the PV system life-cycle (production, installation, disassembling and recycling) is compensated by electricity generated by the PV system. The EPBT is defined by the equation (Sunearthtools, 2011):
EPBT = Einput/Esaved Internal Rate of Return (IRR) Einput: is the energy input during the module IRR is the actual annual rate of profits on an life cycle, investment. It equates the value of cash returns with cash invested. The formula is: Esaved: annual energy savings due to electricity generated by the PV module. Investment cost = The EPBT depends on:
- cell technology, type of encapsulation, i: internal rate of return frame and array support, t: each time interval - PV system application type (grid-connected or stand alone) and, n: total time intervals - PV system performance as determined by This magnitude is essential in order to explain irradiation and the performance ratio. the concept of time value of money. Thus 1€ today will worth more than 1€ in the future. PVTRIN Training course- Solar installers handbook 44
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FIGURE 45 illustrates the EPBT for different Geothermal 80 MW hot dry rock 38 PV technologies. The calculations assume Nuclear various reactor types 66 technologies for average southern Europe various combined 2 insolation (1700 kWh/m /yr), 75% Natural gas cycle turbines 443 performance ratio for roof-top installations, various generator Diesel and turbine types 778 and 80% performance ratio for utility ground- various generator mount installations. Coal types with scrubbing 960 various generator The EPBT values of future PV technology will types without be significantly improved. Recent Coal scrubbing 1050 developments in PV technology will result to decreased energy requirements in A detailed life cycle assessment (LCA) has to components production, leading thus to an be performed in order to calculate the higher potential for fossil energy emissions during the PV system’s lifetime, replacement. which includes extraction and purification of FIGURE 45. raw materials, manufacturing process, PV ENERGY PAYBACK TIMES OF PV TECHNOLOGIES (Source: installation, and many years of operation; Fthenakis & Alsema, 2006) also recycling or disposal of waste products. Values may differ (24gCO2-equiv/kWh), (Moskowitz & Fthenakis, 1991) for PV systems as regards the PV modules type, methods and materials used for the manufacture of the BOS components etc.
Land use Land use is often mentioned as an important issue for RES applications. One of the advantages of PVs in urban areas is that they are installed on rooftops of existing buildings, Emissions so there is no concern for field occupation. Emissions of greenhouse gases are expressed In case of ground mounted PVs, the land use in carbon dioxide equivalents (CO2-equiv). may be quantified by the following metrics TABLE 9. (Turney & Fthenakis, 2011): LIFECYCLE GREENHOUSE GAS EMISSION ESTIMATES FOR ELECTRICITY GENERATORS. (Source: Moskowitz & Fthenakis, - land area “transformation” per nameplate 1991). “peak” capacity (km2 GWp−1), and Technology Description Emissions - land area “occupation” per unit of electrical (g 2 CO2/kWh e) energy generated (km yr TWh−1). Wind 1,5 MW onshore 10 “Transformation” focuses on the one-time Biogas Anaerobic digestion 11 processions that change the physical nature of the land, (installation of the plant) whereas Hydroelectric 300 kW run-of-river 13 Solar 80 MW parabolic “occupation” measures the period that the thermal trough 13 land is being used (including time needed to Biomass various 14-35 recover). The restoration time is highly Solar PV Polycrystaline silicon 32 variable depending on the ecosystem disrupted. PVTRIN Training course- Solar installers handbook 45
PV plants are designed for 30+ years of The PV cell counts for only a small fraction of operation. As the lifetime of a PV plant is the total materials required to produce a getting longer, the land transformation per solar panel. capacity does not change; however, the land TABLE 10. occupation per energy generated decreases. ON MASS BASIS FRACTIONS OF A PV MODULE (Source: PV installations have the lowest land Moskowitz & Fthenakis, 1991) occupation compared to other RES and Components Share compared to the coal and nuclear fuel cycle; Outer glass cover 65% Aluminum frame ~20% for example, the coal power life-cycle Ethylene vinyl acetate encapsulant ~7.5% requires mining that increases essentially Polyvinyl fluoride substrate ~2.5% land occupation. PV plants cover an average Junction box 1% 2 Solar cell 4% of 25 km /GWp. A 30-year old plant occupies 15% less land than a coal power plant of the same age. As the age of the power plant Proper decommissioning and recycling of PV increases, the land use intensity of PV power panels ensure that potentially harmful becomes significantly smaller than that for materials are not released into the coal power (Turney & Fthenakis, 2011). environment; also the need for virgin raw materials is reduced. When batteries are Raw Materials and Recycling used, they have to be decommissioned and Silicon, the material that PV panels are recycled at the end of their life. The most mostly constructed, is one of the most appropriate use of “dead” batteries is to common elements in Earth. It is a nontoxic reuse the lead contained in or recycle them. element; however, several hazardous Recycling technologies exist for almost all chemicals are used during the production types of PV products and most manufacturers process of the solar cells. The basic are engaged in recycling activities. environmental and health issues coming from manufacturing are: Water consumption PV systems do not require water during their - the dispersion of kerf dust, coming from the sawing of silicon ingots into wafers, operation; this fact makes them suitable in places where water is scarce. Some water is - the exposure to solvents, such as nitric acid, used during the production process; 85% for sodium hydroxide and hydrofluoric acid, material extraction and refinement, and 15% used in wafer etching and cleaning. for the module assembly (EPIA, 2011). Solar cells are welded by Cu wire and are Sn coated. Some PV manufacturers utilize Small quantities of water may be also used solders containining lead and other metals for washing panels which is more necessary which if released into the environment may in sandy fields or in Southern European cause environmental and human health risks. countries were sand storms are common. Other environmental risks include the release The estimation for the water needed for of hazardous gasses from fire at the washing the panels, in large scale PV plants, is manufacturing facilities and deposition of 2-4m3/MW/year (Turney & Fthenakis, 2011). lead into soil and, eventually into water bodies. Similar concerns arise when a fire breaks out in a PV plant. Recycling
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IEC/TS 62257-9-5 Recommendations for small 2.5. Standards and regulations renewable energy and hybrid systems for rural electrification – Part 9-5: 2.5.1. International Standards and Integrated system – Selection of portable PV lanterns for rural Regulations electrification projects IEC/TS 62257-9-6 Recommendations for small There are several standards to regulate PV renewable energy and hybrid systems for rural electrification – Part 9-6: system functioning and supervision or Integrated system – Selection of PV standards for advising, planning and Individual Electrification Systems (PV- implementation of such systems. See IES) Grid connected PV systems – following a list of the most important IEC 62446 Minimum requirements for system standards including safety regulations, which documentation, commissioning tests have to be considered during PV systems and inspection IEEE Std 1526 IEEE Recommended Practice for implementation. Testing the Performance of Stand- Alone PV Systems FIGURE 46. STANDARDS FOR PV SYSTEMS INSTALLATION (Source: PVResources, 2011) Standards for batteries, over-voltage Nr Description protection components and other system IEC 60364-7-712 Electrical installations of buildings – components are presented in TABLE 11. Part 7-712: Requirements for special installations or locations – Solar PV TABLE 11. power supply systems. STANDARDS FOR BOS (Source: PVResources, 2011) IEC 61194 Characteristic parameters of stand- alone PV systems Nr Description IEC 61702 Rating of direct coupled PV pumping N 50524 Datasheet and nameplate information of systems PV inverters IEC 61724 Photovoltaic system performance EN 50521 Connectors for PV systems – Safety. monitoring – Guidelines for IEC 61173 Overvoltage protection for PV power measurement, data exchange and generating systems – Guide analysis IEC 61683 PV systems – Power conditioners– IEC 61727 PV systems – Characteristics of the Procedure for measuring efficiency utility interface IEC 61427 Secondary cells & batteries for PV systems IEC 61683 Photovoltaic systems – Power – General requirements and methods of conditioners – Procedure for test measuring efficiency IEEE Std. 937 Recommended practice for installation IEC 62093 Balance-of-system components for and maintenance of lead-acid batteries PV systems – Design qualification for PV systems natural environments IEEE Std. Recommended Practice for Sizing Lead- IEC 62116 Test procedure of islanding 1013 Acid Batteries for PV Systems prevention measures for utility- IEEE Std. Recommended practice for determining interconnected PV inverters 1361 performance characteristics and IEC 62124 PV Stand-Alone Systems – Design suitability of batteries in PV systems Qualification and Type Approval IEC/TS 62257, Recommendations for small 2.5.2. National Standards and renewable energy and hybrid systems for rural electrification Regulations IEC/TS 62257-7-1 Recommendations for small renewable energy and hybrid systems for rural electrification – Part 7-1: Greece Generators – PV arrays There are no official requirements concerning IEC/TS 62257-8-1 Recommendations for small renewable energy and hybrid systems the PV systems equipment, in Greece. for rural electrification – Part 8-1: However, technical actors who want to be Selection of batteries and battery registered in the list developed by Centre for management systems for stand-alone electrification systems Renewable Energy Sources (CRES) have to PVTRIN Training course- Solar installers handbook 47
use panels and inverters to meet minimum Interconnected System: Voltage: -20% to standards acknowledged in EU level. +15% of nominal frequency: +/- 0,5Hz For PV panels Non-Interconnected Islands: Voltage: -20% to +15% of nominal frequency: from 51 Hz to - IEC-EN 61215 η 61646, 47,5Hz. - IEC 61730 – Class A (Class II insulation) The pricing of electric energy produced by These certificates are provided by accredited photovoltaic stations as it applies, is carried laboratories. out based on the data of the following table: For Inverters TABLE 12. P PRICES FOR ENERGY PRODUCED BY PV - Confirmation of protection against Interconnected Non- islanding, according to VDE 0126-1-1 or System Interconnected Year-month Islands equivalent method Euros/MWh - Protection against voltage and frequency >100kW ≤100kW of any capacity limits (hypertension, hypotension, 2010 February 400,00 450,00 450,00 hyperfrequency) 2010 August 392,04 441,05 441,05 - Total Harmonic Distortion (THD) current output less than 5%, manufacturer 2011 February 372,83 419,43 419,43 compliance certificate (optional). 2011 August 351,01 394,88 394,88 - In case of electronic converters without 2012 February 333,81 375,53 375,53 iron, core transformer the maximum 2012 August 314,27 353,56 353,56
injected DC to the grid must be less than 2013 February 298,87 336,23 336,23 0,5% of the nominal output current of 2013 August 281,38 316,55 316,55 converter, manufacturer compliance certificate (optional) 2014 February 268,94 302,56 302,56 These requirements are necessary in order to 2014 August 260,97 293,59 293,59 From 2015 fulfill the conditions of proper operation 1,3 *mts(ν- 1,4*mts(ν- and after, for referred in the contract signed between the 1)1,4*mts(ν-1) 1)1,5*mts(ν-1) each year (v) PPC and producer. mts(ν-1): marginal tariff system the previous year ν-1 In Greece there are no statutory regulations for the installation of PV systems. PV technicians follow basic principles according For PV systems of up to 10kWp, in the to the ELOT 384 “Requirements for electrical domestic sector and in small businesses, the Installations” (Hellenic Organization for PPC (Public Power Corporation) will buy the Standardization, ELOT). energy produced for 0,55 € / kWh. This price is guaranteed for 25 years. The producer – According to the Public Power Corporation consumer continues to buy power from the (PPC), PV systems up to 100kW are PPC (about 0.10-0.12 € / kWh). Revenues connected to low voltage, via single phase from energy sales are not taxed. power supply for up to 5kW and three-phase power supply for systems more than 5kW Moreover, following to the adoption of the and up 100kW. RES legislation (Law 3851/2010) and the subsequent Ministerial Decisions, some The default settings of the protection voltage important changes have been applied in the limits and frequency should be as follows: PVTRIN Training course- Solar installers handbook 48
2 DESIGN PRINCIPLES
normative framework overcoming some - Hellenic Association of Photovoltaic administrative barriers. Companies: http://www.helapco.gr/ - Solar Energy Producers' Association: www.spef.gr More specifically:
- Production license is not required for TABLE 14 and TABLE 15 present the current systems <1 MWp. legislation, administrative issues and - Rooftop systems of any size do not require supporting mechanisms (valid on September environmental permitting and procedures 2011) for the countries participating in the have become easier for ground-mounted PVTRIN Project (Bulgaria, Croatia, Cyprus, systems. Greece, Romania, Spain). - Residential systems can be installed in all Furthermore, the PV LEGAL project has regions developed a database comparing the - Applications previously excluded (such as administrative procedures for PV installations facades, louvers, warehouses, carports, etc) in the 12 EU Member States (Bulgaria, Czech are feasible in the residential sector. Republic, France, Germany, Greece, Italy, - PV systems on historical buildings can now Poland, Portugal, Slovenia, Spain, the be deployed under a special authorisation Netherlands and UK). Three different types procedure. are examined: -Small-scale installations on - Installation of PV systems on prime residential buildings -Small to medium-scale agricultural land is now allowed with certain installations on commercial buildings - limitations. medium to large-scale ground-mounted - A 150 €/kWp bank guarantee is needed for installations on open lands. The database ground-mounted systems up to 1 MWp identifies the administrative steps necessary before the signing of a grid connection to obtain permission for constructing, grid- contract. connecting and operating of PV systems that could be a very helpful tool for both the
installer and the customer. The PV LEGAL is The above data are in force at September funded by the European Commission’s 2011, and they are subject to change. Intelligent Energy for Europe programme (PV LEGAL, 2011). The installers are strongly advised to look for the latest legislative and normative framework before start developing a PV project. Valid legislation, supporting mechanisms and applicable rules are published to the following links: - Public Power Corporation: www.dei.gr - Regulatory Authority for Energy:
www.rae.gr - Hellenic Transmission System Operator S.A: www.desmie.gr - Ministry of Environment, Energy and Climate Change: http://www.ypeka.gr/ PVTRIN Training course- Solar installers handbook 49
2.6. Databases A number of databases have been developed to offer useful information in different aspects of a PV installation. Indicative links are listed to following table (TABLE 13).
TABLE 13. PV DATABASES
Links Description Information on solar power and its applications. large www.pvresources.com/ scale PV power plants database on reports simulation tools Data on best practices, urban www.pvdatabase.org/ PV projects, BIPV products National reports and www.iea-pvps.org/ statistiics on PV market Detailed information on the administrative processes that need to be followed in www.pvlegal.eu order to install a PV system in each of the participating countries. Information on production equipment, solar http://www.enf.cn/database components (eg. inverters, /panels.html batteries), solar materials, solar panels, sellers, solar system installers ¡Error! Referencia de Extensive database with hipervínculo no characteristics of many PV válida.database.aspx panels Database of all commercially available solar panels with http://pvbin.com/ functionality to search and sort by different data parameters http://www.nrel.gov/pv/ performance_reliability/failu Information about failures re_database.html observed in PV installations. database including over 750 PV facilities and covering the http://www.semi.org/en/Sto PVindustry value chain from re Poly-Si to module /Marketinformation/photov manufactures. Resource for oltaics/CTR_028755 key business and technical contacts Climatological database for solar energy applications: a meteorological database www.meteonorm.com containing comprehensive climatological data for solar engineering applications at all points of the globe
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TABLE 14. ADMINISTRATIVE ISSUES
Greece Bulgaria Croatia Cyprus Romania Spain Permission issued by the Planning Permission based on an PV system on existing buildings is Direction 2/2006 issued to A permission is required CTE-HE5: Technical Building and Architectural Commission is assessment of the impact viewed as simple building, no guide Planning Authorities in for all modifications to the Code” follows the spirit of required in case of PV installation. on the environment is location permit is needed, thus relation to the principles, building from the CPD (Construction Products a. in areas characterized as “areas of required. Installation of PV can be easily installed on the criteria and procedures, for Urbanism department of Directive) and international natural beauty” and any RES systems in roofs, facades etc. However, permitting RES installations each municipality – Law technical codes in the sense b) in areas where listed buildings are, protected areas is very during a procedure for Eligible and apply building permit no.10/1995 on “Quality that it focuses on target as well as traditional settlements. limited. For the installation producer status, the control to applications that are construction” performances. PV installation is permitted on of PV systems on arable Confirmation that there is no related to their integration. It establishes the minimum buildings’ roofs and facades, veranda land a special permit is need for location/construction Circular 3/2008 includes The restrictions apply to solar photovoltaic electric covers and shelters. required. permit from local (municipality) specific provisions that are historical areas buildings. capacity to be installed in PV array should not: (Law for Protected office for construction permits is related with installation of certain types of buildings, -create a space of main or auxiliary Territories, Regulation No needed to obtain. small scale photovoltaic Law no.10/1995 on regulates the size of the usage or semi open areas 2 for construction works Some protected areas could be systems in buildings or on the “Quality construction” facilities and the layout of
- hinder the access in communal on arable lands) excluded. ground and states clearly in amended by the modules, and gives areas There are no specific Recommendation is to make a which cases the application for Governmental Decree no. maximum values for losses - exceed the frame -in penthouses architectural requirements static calculations and electric planning permit is not 498 /2001, Law no. 587 depending on the type of (enclosed area on top of a building) for the installation of PV design before installing PV required. /2002 and Law no. 123 installation: general case, - be installed at the end of the well on buildings. The systems modules on roofs. The 2006 Law on Regulation of /2007. Permission is superposition and hole should be designed Only limited number of Energy Efficiency in Buildings required for all architectural integration - In sloped roofs PV panels must be according the rules for municipalities/counties foresees (L.142(I)/2006) – PPR 446/2009 modifications to the placed following the inclination of the electrical installations that use of PV on buildings in their For new buildings should be building from the Local urban legislation; housetop guarantee a safe spatial plans. foreseen the provision for Urbanism department of - In case that PV panels are placed on exploitation. The design Use of alternative energy sources future installation of PV’s. In each municipality. The the roof of the building, distance should be approved from (including PV) must be agreement with the Electricity restrictions apply to from the parapet of the roof should the relevant authorities. elaborated for every new Authority, should be installed a historical and religious be at least 0.50 m for safety reasons. (Regulation No 1 from building; however, not any is bigger electricity panel board buildings. For PV installation on buildings > 27.05.2007 for designing, required to be built in final. and a cable from the panel 100kWp, approval of small scale installation and board to the future likely place construction work is required. maintenance of low of RES-e installation. voltage electrical
Building regulations relevant to PV installation installations in buildings).
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Planning For the installation of photovoltaic Yes, as for all electrical For smaller PV plants: not - only for PV parks 20-150kW& Yes Yes permission systems on buildings (less than systems required. For large PV plants: PVs on buildings over 100kW required for 100kW) planning permission is not Local Spatial Planning office has PV required to change use of the land, and installation accept it in Spatial Plan (long and complicated procedure) Requirement There is a limit for installations ≤ 100 The Bulgarian distribution - ≤4.6 kW – one phase Connecting RES to the There are no regulations Compliance with the s for Grid kW. PV systems greater than this grid has no specific connection electricity network follows the for private owners, only following regulations connection imply the connection to the medium requirements for the - > 11.04 kW –3phase connection Regulation regarding the for producers that have a RD661/2007: it regulates the voltage network. connection of a PV plant. - PV plants ≤ 100 kW connection of users to public license for activities of transport, PV systems >2MW have to be Regulation №6 from Directly connected to low- interest electricity networks producing/distributing distribution and electricity connected to high voltage network. 09.06.2004 “Connection of voltage line (0.4 kV) and following the specifics of electricity commercialization. producers and users of - PV plants ≤ 500 kW are the Electricity Law no. 13/2007 All the necessary steps are -RD 1578/2008: minimal electrical energy to the connected on the low voltage with subsequent updates by described in the requirements for the transmission and (0.4 kV) on connection point in GD 90/2008. “Guidelines protection against electrical distribution grids” transforming station for the producer of risk - PV plants ≤ 10 MW are electricity RD 1663/2000: Low Voltage connected on the medium from renewable energy Regulation voltage (up to 35 kV) on sources (e-res)” . - OM 5/9/1985: High Voltage connection point in transforming Regulation. station - RD 1110/2007, unified - All power plants are required measure points of the for approval from DSO electrical system. Links for - Public Power Corporation: Ministry of Regional - Ministry of Economy and - Cyprus Energy Agency - Ministry of Regional - Technical Building Code:Formatted: Left, Indent: Left: 0 cm, Don't valid www.dei.gr Development and Public Ministry for Construction: http://www.cea.org.cy Development and - www.codigotecnico.org adjust space between Latin and Asian text legislations - Regulatory Authority for Energy: Works - http://oie.mingorp.hr Tourism www.mdrt.ro - Official State Gazette www.rae.gr www.mrrb.government.bg - Ministry of Environmental - - Romanian (BOE): www.boe.es - Hellenic Transmission System State Energy and Water Protection, Physical Planning Energy Regulatory Operator S.A: www.desmie.gr Regulatory Commission and Construction: Authority: http://anre.ro - Ministry of Environment, Energy www.dker.bg www.mzopu.hr and Climate Change: Ministry of Economy and - Ministry of Economy, Labour http://www.ypeka.gr/ Energy and Entrepreneurship: - Hellenic Association of www.mi.government.bg - http://oie.mingorp.hr Photovoltaic Companies: State Gazette - Hrvatska Elektroprivreda (HEP http://www.helapco.gr/ http://dv.parliamnet.bg Group): www.hep.hr Formatted: Left, Indent: Left: 0 cm Source: PVTRIN, 2011 Note: TABLE 14 and TABLE 15 present the current legislation, administrative issues and supporting mechanisms (valid on September 2011) for the countries participating in the PVTRIN Project. Use the links above to see the current legislations.
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TABLE 15. SUPPORTING MECHANISMS TO PV INSTALLATION
Greece Bulgaria Croatia Cyprus Romania Spain
Supporting PV systems ≤100 kWp: According to the new RES Law (2 /05/2011): FIT from RES&PVs 0,32- Natural persons & Six green certificates for FIT 0,1385€ / kWh (2011) mechanisms and 0,45€ / kWh Electricity PV installations will be supported 0,52 €/kWh depending of organizations, not involved in each 1MW produced and incentives for the PV systems ≤100kWp: by high tariffs for 15 years that will be the size of PV plant. Cap economic activities delivered by the 50% of the IBI, reduction installation of PV 0,40€ / kWh. defined every year by the State Energy and on total of 1 MW of PV (residential): producers of electricity between 0-100% of the urban Water Regulatory Commission. Since 1/07/ plant. Grid connected from solar energy. canon and reduction from 0- 2011 the tariffs from PVs are: Level of FITs will changed, <7kW : FiT 0,35€/kWh (15ys, 95% of the ICIO. BIPV: <30 kWp on roofs or facades: 0,31 as well as cap with new no grant) Depending on the region: Soft €/kWh Law on Renewables that is Stand –alone loans, Tax incentives, Regional BIPV: 30 -200 kWp on roofs or facades: 0,30 drafting, and is expected <7kW: 55% grant investments, VAT devolution €/kWh to be in power by the end < 20 kW (organizations): 55% BIPV >200 kWp on roofs/facades: 0,30 €/kWh of 2012. grant (max €44.000) For ground PVs <30 kWp: 0,29 €/kWh For updated information: Natural persons & For ground PVs 30 -200 kWp: 0,29 €/kWh Ministry of Economy: organizations, involved in For ground PVs >200 kWp: 0,25 €/kWh http://oie.mingorp.hr/ economic activities: The Kozlodui National Fund administrated Grid connected by EBRD offer loans. Usually RES owners are 21-150kW : FiT 0,31€/kWh granted a 20% discount from the principal (20ys) sum of the loan after the completion of the Stand –alone< 20 kW: 40% project. USAID program guarantees 50% of grant (max €36.000) the credit. depending on the enterprise Supporting PV systems < 10kWp in the The Kozlodui National Fund administrated The above specific category. < 20 kW : 0,2979€/kWh (2011) mechanisms and domestic sector and in by EBRD. supporting mechanism will In the cases of stand-alone 20 kW–2 MW: 0,2095€/kWh incentives for the small businesses: 0,55 € / The USAID program and some banks (credit be implemented in new systems there is a maximum (2011) installation of kWh. lines). Law on Renewable as amount of grant i All this under the consideration BIPV Programs for regional development somewhat higher FIT. Comment: Likely to be of not fulfilling the total amount http://oie.mingorp.hr changed in 2012. of installations “allowed” Links for current - Ministry of Environment, -Ministry of Commerce, - Ministry of Regional legislation Energy and Climate Industry and Tourism: Development and - Ministry of Economy, Change: www.ypeka.gr/ www.mcit.gov.cy Tourism www.mdrt.ro Labour and - Hellenic Association of Cyprus Institute of Energy: Entrepreneurship: PV Companies: www.cie.org.cy http://oie.mingorp.hr www.helapco.gr/
- Solar Energy Producers' Association: www.spef.gr Source: PVTRIN, 2011 Note: TABLE 14 and TABLE 15 present the current legislation, administrative issues and supporting mechanisms (valid on September 2011) for the countries participating in the PVTRIN Project. Use the links above to see the current legislations.
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2.7. Exercises A = 3 days E = 940Wh 2.7.1. Case studies T = 0,5 Case Study 1 ninv = 0,9 Sizing a 24VDC system voltage home ncable = 0,97 (Kamnang and Menke, 2010). The minimum battery capacity required, Ah i. The loads and appliances and, the daily energy requirement
TABLE 16. APPLIANCES AND DAILY ENERGY REQUIREMENTS As we have a 24VDC home system, 2
Loads and Power Total Hrs of Daily batteries with 24V/150Ah connected in Appliances rating of power use/d energy parallel will be chosen for a total of appliances required (h) requireme 24V/300Ah. (W) (W) nt (Wh) iv. Inverter Fluorescent 12W 60W (5 3 180Wh lamps lamps) The system requires an inverter, as there are TV 100W 100W 1,5 150Wh only AC appliances in the house. The total Microwave 640W 640W 0,5 320Wh power required for AC appliances is 940W Refrigerator 80W 80W 3 240Wh that means a 1.500W inverter with 24VDC Lighting 60W 50W 1 60Wh input will be recommended. outside v. Wiring TOTALS 940W 950Wh In case that the cables length is 8m and made of copper and the drop voltage is 10%. The house’s roof has an inclination of 50°C and is orientated 60° southwest. The system is design for January and a 3 days storage capacity is foreseen. ii. Module sizing (See also chapter 2.2.10) G = 5,0 PSH nSYS = 0,6 This result will be rounded to the next E =940Wh daily energy requirement. 2 standard value 6 mm . 2 The standard cross-section sizes are 2,5mm ; 4mm2; 6mm2; 8 mm2; 10 mm2; 12mm2; 14 This means that the minimum size of the mm2 ; 16 mm2; 18 mm2; 20 mm2; 22 mm2; 24 module is 314 Wp. ; 26 mm2; 28 mm2; 30 mm2; 32 mm2. iii. Sizing the battery (See also chapter 2.2.10) We selected a 80Wp mono-crystalline PV V = 24VDC the system voltage. module of about 21VDC (a nominal voltage rate of 12V) with a nominal current of 4,5A. PVTRIN Training course- Solar installers handbook 54
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If we divide 314 by 80 we will have 3,9, so 4 depends on the length and the width of the modules will be connected in series-parallel. roof. This means 2 modules connected in series, and the 2 strings are connected in parallel. The total voltage is 2 x 12 V = 24VDC and the ii. Check if the module fit the roof current is 4,5A x 2 =9,0A. - In portrait format The current produced by the module Roof length 9,0m = = 9,35 and determines the charge controller. In this case Module width 0,962m Roof width 5,0m it is 9A. The charge controller has a minimum Module = 1,550m = 3,23 of 9A. We can choose a greater one (15A) in length case of any expansion. This makes a total of 9 x 3 = 27. The maximum number of modules laid in portrait that could
fit the roof is 27 (9 modules and 3 strings or Case Study 2 opposite) enough space for the 24 modules.
Sizing a 5,5kWp PV system on a slope roof - In landscape format (length 9,0 m, and width 5,0 m). (Kamnang Roof length 9,0m = = 5,8 and and Menke, 2010). Module length 1,550m Roof width 5,0m = 5,19 TABLE 17. Module length = 0,962m PV -MODULE’S CHARACTERISTICS 5 x 5 is approximately 25, so maximum 25 (5 Parameter Value modules and 5 strings) modules can also fit in Maximum power Pmax 230 landscape format.
Voltage at Max. power VMPp 29,8V The modules can be laid in both formats, but Current at Max.power IMP 7,7 it is better to choose the format in which
Open Circuit Voltage VOC 35,8 more modules could be laid so that the
Sort Circuit Current ISC 8,34 system could be extended in the future. So the portrait format is selected. Max. System Voltage 1000V
o Voltage (VOC) -0,35%/ C iii. Checking the module voltage
Temperature coefficient o Current (I SC) 0,060%/ C Voltage temperature coefficient: - 0,32% x Length x Width x Depth mm 1550x962x40 Voc/°C= -0,0035 x 35,8 = - 0,125V/°C Weight kg 18,5 VMPP – 25°C = 29,8V
2 1,550m x 0,968m = 1,500m for 230 Wp. This VMPP – 10°C = 29,8 + 15x 0,125 = 31,67V 2 is equivalent to 6,5 m /kWp VMPP -70°C = 29,8 – 45 x 0,125 = 24,18V
Voc -10°C = 35,8 + 15 x 0,125 = 37,67 V i. Roof size needed 2 2 5,5kWp x 6,5 m /kWp =35,75m iv. Inverter selection Total module need: 5.500Wp/230Wp = 23,9 Inverter nominal power is between 90% and thus 24 modules will be consider for a total 100% of (array) this is between 90% x 5.520= power of 24 x 230 W= 5.520Wp 4.968W and 5.520W (this range is chosen Modules should be checked if laid out on because in case of good sunny days with portrait format or landscape format. This radiation at the STC or over the STC, the
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inverter should not be undersized), so 4 2.7.2. Multiple Choice Questions inverters (TABLE 18) can be chosen for a string-inverter concept. 1. What is meant by the standard test condition (STC) TABLE 18. INVERTER’S CHARACTERISTICS a) radiation: 1000W/m2, temperature: 25°C, Parameter Units Value and Air Mass: 1.5 Max DC power W 1400 b) radiation: 1000W/m2, temperature: 20°C, Max DC voltage V 400 and Air Mass: 1.5 V-voltage range, MPPT V 96-320V c) radiation: 1024W/m2, temperature: 25°C, Max Input Current A 12,6 and Air Mass: 1.5 v. Module configuration d) radiation: 1000W/m2, temperature: 18°C, Maximum number of modules on a string: and Air Mass: 1.0 2. If a PV cell produces 0,5 V then four PV cells connected in series will produce: Minimum number of modules on a string: a) 2,0 V
b) 0,5 V Therefore the maximum number of modules (c) 2,5 V is 8 and minimum 4 on a string. (d) 1,0 V vi. Array configuration and inverter compatibility 3. The total power across four PV cells of 0,5V connected in series when Acell = 1A is: 4 strings of 6 modules with 1 inverter on each string, will be implemented. The voltage (a) 2,0 W compatibility has to be checked. (b) 0,5 W
VMPP -70°C = 6 x 24,18V = 145V this is above (c) 2,5 W the lower voltage of MPP-range (96V) (d) 1,0 W acceptable VMPP 4. If a PV cell delivers a current of 0,6 A and V = 6 x 31,67V = 190 V this is below MPP – 10°C there are three PV cells in parallel then the the upper limit of the MPP voltage range current flowing through the load is: (320V) also acceptable VMPP a) 2,0 A Voc -10°C = 6 x 37,67= 226V this is below the maximum inverter input voltage (400V) also b) 0,6 A acceptable Voc c) 1,8 A The current at the MPP of the module is d) 1,0 A 7,71A, below the maximal input current of the inverter (12,6 A) also acceptable 5. The total power across three PV cells of 0,5V connected in parallel when Acell = 0,6 A This is a string-inverter concept. The array has is: a total wattage of 5.520kWp consists of 24 modules with 230 Wp each. The array is a) 2,0 W configured in 4 strings of 6 modules. b) 0,9 W
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c) 0,3 W a) the positive terminal is connected to the positive terminal d) 1,0 W b) the negative terminal is connected to the 6a. If 24 PV cells (0,5V) are connected in negative terminal series and parallel (6 cells and 4 rows), the total voltage across the load is: c) the positive terminal is connected to the negative terminal a) 2,0 W d) all of the above b) 2,4 W 12. A stand-alone PV system can provide c) 12,0 W electricity when no sunlight is present with: d) 3,0 W a) batteries 7. If the height of an obstacle is 3m the b) no batteries minimum distance (Lmin) so that the PV will not be shaded is: c) a battery charge controller a) 4,0 m d) a and c b) 6,0 m 13. An inverter is required on a PV system if: c) 3,0 m a) batteries are used d) 1,0 m b) DC power is needed 8. “Increase in temperature leads to an c) AC power is needed increase in Voc resulting to increased cell d) if the load is very large output”. The statement is: 14. If a PV system is tied into the electric a) Right utility grid: b) Wrong a) it does not have to use batteries c) Further information is needed to decide b) it needs batteries 9. The efficiency of a PV cell may be improved c) it requires power storage by: d) it cannot provide AC a) adjusting the light facing angle all day 15. The available surface area of a building is b) placing colored acetates on the cell 108m2 (length=12,0m and width =9,0m), and c) cooling the cell the area required by a panel is length=1,64m and width =0,98m. If 55 PVs are to be d) changing its direction to north installed the optimum way is in: 10. Solar PV systems can be: a) landscape format a) connected to the power grid b) portrait format b) used to sell power to the grid c) there is no difference c) a stand-alone source of electricity d) none of the formats is appropriate d) all answers a, b, c 16. A battery Wh-efficiency is always smaller 11. In a series connection: than its Ah-efficiency.
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a) Right 2.7.3. Correct–Wrong Questions b) Wrong 1. Tracking to the sun’s daily migration can c) We cannot know boost production up to 8%. 17. A 100 watts refrigerator can operate 2. Shadows analysis for different locations using a 150 watts inverter without any can easily be performed by a technician. problems. 3. The results of even when half of a cell is a) Right shaded, is the same as if half of a row is shaded. b) Wrong 4. The maximum voltage occurs when there is c) We cannot know a break in the circuit. 18. A 24 volt back-up power system is 5. Deep discharge improves life expectancy of supplied via a single, 4mm2 solar cable, 15m a Pb-acid battery. long, from a 200 watt module. Is the cross- section sufficient? 6. Temporal overcharge of a battery improves the homogeneous of the catalyst. a) Yes 7. When sizing the cables, the permitted b) No current rating of the cable should be at least c) We cannot know equal or greater than the trigger current of the string fuse. 19. To improve the efficiency of the whole system from the planning procedure, the 8. The efficiency of string inverters range designer should? from 50-60%. a) Install the modules in a way that they will 9. The share of the panels in the total be well ventilated system’s cost is about 70-80%. b) Keep the cables as long as possible 10. A safety distance of 0,10Ì between the PV plant and all parts of the lightning protection c) Keep the tilt of the panels less than 15o system has to be kept. d) None of the above 11. The lifetime of the system is 10-15 years. 20. A string concept with 8 inverters is 12. The material that cells are made is toxic planned for the PV system with 12kWp. What and hard to be found on Earth. the DC output that each inverter should have? Between… 13. Αll available online softwares for PV system dimensioning provide accurate a) 1,35 and 1,5 kW calculations and reliable data. b) 0,67 and 1,42 kW 13. The most expensive component of an c) 1,35 and 1,42 kW autonomous PV system are the batteries. d) None of the above 14. A rough estimation of the average value of a PV system is approximately 8.000 €/kWp.
15. An approximate available surface can be
estimated by having in mind that: 10m2 = 1kWp
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2.7.4. More Practice 10. Which is the part of the PV system that ensures max output power from the PV 1. A PV system uses 720 silicon PV cells module? connected in an array which supplies up to 120 V. 11. Under which circumstances a PV system could cause environmental damage? a. How many PV cells are connected in series if 120 V are needed but one cell 12. Why should the PV systems be recycled? delivers only 0.5 V? What is the number of 13. Name 3 parameters on which a PV the rows connected in parallel? system’s energy payback time is depending b. When the light intensity is 1000 W/m2, on. the total power output from the PV array is 360W. What is the energy efficiency of the PV cells? What type of silicon PV material are the PV cells made from? Each PV cell is square of 118mm by 118mm.
2. Which is the appropriate charge controller for a PV system with 30 modules of total power 47Wp connected to a 24V battery? The connection of the modules is implemented to 15 branches of 2 panels per series and the maximum voltage of each module is 17V. Take into account that 6 lamps of 60W and a CD player of 160W operate at the same time. 3. 130 kWh of energy is used to produce 1 m² Poly-Si module. How long will take for this module to return the energy used for manufacturing, given that solar irradiation in Greece is 1350 kWh / (m² x yr)? 4. Explain briefly how the PV panel’s efficiency is influenced by temperature variations. 5. What is the optimum panel inclination for a panel sited in Crete (φ=35,16ο). 6. How does an inverter work? Why this is an essential part of a PV system?
7. Name 3 of the most common losses of a
PV system. Explain.
8. Which is the role of a blocking diode?
9. Which are the main requirements of a stand-alone inverter?
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BAPV and BIPV 3
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3. BAPV and BIPV Building-integrated photovoltaics (BIPV) are 3.1. Mounting and building photovoltaic prioducts (sheets, tiles, glasses, etc.) that are used instead of conventional integration options building materials in parts of the building envelope such as the roof, skylights, or 3.1.1. BAPV and BIPV facades. They usually are installed in new buildings, but they could also be installed in Building-applied photovoltaics and building- existing buildings at renovation. The integrated photovoltaics are PV modules advantage of BIPV is that the costs of installed in buildings as a principal or construction are reduced, as these modules additional energy source. The installation of a replace traditional building materials. On the PV system in a building is a very sustainable other hand, solutions with BIPV modules are solution, as there is no need of additional usually more aesthetic. land, we use roofs and facades. FIGURE 49. BIPV ON ROOF. (Source: SEC ) Building-applied photovoltaics (BAPV) are photovoltaic installations fixed over the existing elements of buildings’ envelope as roof, skylights, facade, balconies and shelters.
FIGURE 47. F BAPV ON FALT ROOF. (Source: SEC )
3.1.2. Building integration options BAPV and BIPV can be installed in all type of buildings as dwelling buildings, houses, FIGURE 48. schools, all types of public buildings and BAPV ON PITCHED ROOF. (Source:SEC ) industrial buildings as well in urban structures as bus/parking shelters. The key components of a grid-connected system are:
• The PV modules, • The inverter, • The current meter.
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FIGURE 50. ALTERNATIVES FOR INTEGRATING PVs IN BUILDINGS (Source: SST)
The criteria for good integration of PV Several issues should be taken into modules in buildings are: consideration at urban planning for a good integration of PV systems in buildings: • Natural integration, • Architectural solutions, - For PV on sloped roofs, the streets should • Pleasant composition of materials and be oriented east-west, in order to have colours, south oriented slopes. • In line with the context of the building, - For PV integrated in facades the optimal • Innovative design. orientation should be chosen, depending on the open spaces.
- Shading from other buildings or trees
should be taken into account and
minimised.
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FIGURE 51. 3.2. BIPV and BAPV on roofs OPTIONS FOR INTEGRATION OF PV SYSTEMS ON FLAT ROOFS (Source: ECN). PV elements can be installed on all types of roofs – flat roofs, pitched roofs or domed roofs.
3.2.1. PV modules on flat roofs The installation of PV modules on flat roofs is an excellent choice, as the modules can be oriented and inclined in the best position. When installing PV modules on a flat roof, several aspects should be taken into account:
• The structure of the roof, • The elements of the roof as chimneys, exits, skylights, etc., • The orientation of the building.
The FIGURE 51 illustrates different options for integration of PV systems on flat roofs. (ECN). When PV modules are installed in new buildings, the structure of the roof is calculated according to the load of the installation, but when they are installed on existing buildings, the load bearing capacity of the structure should be checked. In some case, the roof structure should be reinforced according to the requirements of the building regulations. PV modules on flat roofs are fixed on metal structures or adapted concrete or plastic structures. At the installation of the structures (metal or plastic) it is necessary to preserve the water- proofing covering of the roof. The elements for fixation of the structure to the roof should be insulated with water-proof materials.
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FIGURE 52. 3.2.2.F PV modules on pitched roofs PV INSTALLATION ON FLAT ROOF – EXTERNAL VIEW AND STRUCTURE. (Source: SEC ) There are several integration options for installing PV modules on pitched roofs. They can be mounted over roof (BAPV) or integrated in the roof (BIPV).
FIGURE 53. OPTIONS FOR INTEGRATION OF PV SYSTEMS ON PITCHED ROOFS (Source: ECN). a) mounted over tiles (BAPV)
b) integrated in the roof (BIPV)
When planning the installation of the structure, the elements of the roof should be taken into account. PV modules should not c) The whole roof can be covered with PV modules (BIPV). be installed close to chimneys, exists or paths. Flat roofs are very convenient for PV systems, as they can be oriented in the best position, but distance at least ½ of the height of the structure should be left between the rows of PV modules in order to avoid mutual shading. Shading from chimneys and walls should also be examined.
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d) solar tiles TABLE 19. PROBLEMS AND SOLUTIONS AT INSTALLATION OF PV MODULES ON PITCHED ROOFS . (Source: SEC)
Problems to be Solution solved Stainless steel Good fixation of PV elements stuck modules without under the tiles for damaging the roof’s fixing the covering structure e) PV modules installed with an air gap on the rear to ensure The distance the necessary ventilation and avoid problems with over- BAPV between the PV heating, Ensure good air elements and the circulation on the roof’s covering rear should be 5-10 cm.
Use special Water tightness products as : PV between the panels roof tiles/sheets, BIPV and between the follow strictly the panels and the roof recommendations covering of the manufacturer
BAPV on pitched roofs FIGURE 54. BAPV have an independent support structure BIPV ON RESIDENTIAL BUILDING (Source:SEC) and are easier for installation. They are more suitable for retrofits of existing buildings than BIPV. Because of their independent structure they are cooled from the rear and there is no problem with over-heating. They can be easily replaced.
BIPV on pitched roofs BIPV offer better possibilities for a good integration.
Mutual shading is avoided.
Be careful to ensure good water tightness and ventilation.
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FIGURE 55. 3.3. PV on facades OPTIONS FOR INTEGRATION OF PV SYSTEMS ON FLAT ROOFS (Source: Education and training material for architects, (ECN). In order to reach the requirements of the Energy Performance of Buildings Directive (EPBD), which requires all EU countries to a) fully integrated. enhance their building regulations, it is necessary to foreseen enough renewable energy sources. Although the roofs are the best place for installing PV modules, space for PV elements should also be foreseen on the facades as the surface of the roof will not be enough to ensure the required amount of energy production. b) partly integrated. When examining the installation of PV modules on facades, it should be taken into account that the efficiency of the system will be at least 30% lower, than these of a system installed on the roof with the best tilt and orientation.
3.3.1. Options for integration c) additional glass façade. There are several options for integration of PV modules on facades. a) fully integrated. b) partly integrated. c) additional glass façade. d) fixed on the balcony. d) fixed on the balcony.
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3.3.2. BAPV on facades 3.3.3. BIPV on facades BAPV is a good choice for installing PV BIPV are suitable for new buildings. They give systems on facades of existing buildings. better opportunities for good architectural solutions.
BIPV installations can be integrated in BAPV can be cheaper than BIPV because: buildings as warm facades. In this case they • One of the advantages of BAPV systems are integrated in the structure of the façade is that it is easier to ensure cooling of as a part of the wall. In this case, the PV the system through the air gap between modules are fixed between two glasses and the PV panels and the wall. are incorporated in the structure of the • There is no need of cladding or façade. The façade panels can be composed decorative plastering on the walls by a glass package with PV modules and a behind the PV panels. sandwich panel with thermal insulation as • There is no need to ensure air tightness shown in figure 57, or glass-glass package between the joints. where the sandwich panel is replaced by • BAPV are easier for maintenance and argon filled space and thermal coating on replacement. float glass as shown in figure 58. • The PV panels can act as additional
thermal insulation. FIGURE 57. BIPV IN WARM FACADE (Source:SST) FIGURE 56. F BAPV ON REFURBISHED RESIDENTIALLA BUILDING (Source:SEC)
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• A fully glazed façade, • Alternation of PV modules and glass.
The following figures show different examples of integration of modules in façade construction. (SST, 2008)
FIGURE 58. BIPV IN WARM FACADE (Source: SST, 2008)
With the integration of the modules in the structure of the façade can be reached different architectural solutions as:
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than 20 cm., it can be even like a glazed balcony.. Cold facades are more expensive as the modules are additional elements of the construction, but they have other benefits. The solution with cold façade avoids the problem with cooling of the modules. This second “skin” acts as a very efficient additional thermal insulation and can ensure a better indoor climate. With a good planning of the cold façade it is not necessary to foresee additional shading.
FIGURE 59. BIPV IN COLD FACADE (Source: SST)
BIPV installations can be integrated in buildings as cold facades. In this case they act as second “skin” of the facadefaçade, or a double façade. PV modules are fixed on an additional structure with an air space between the modules and the wall. Depending on the distance between the modules and the wall we can examine facades as: • Ventilated facades when the space Formatted: Bulleted + Level: 1 + Aligned at: between the wall and the modules is 0,63 cm + Indent at: 1,27 cm
up to 10cm., as the fixing of the PV modules is not air tightened, the air can circulate between the wall and the modules and secure the necessary ventilation. In these facades the PV modules act also as finishing cladding.
• Curtain wall – the distance between the wall and the PV modules is more
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3.3.4. Mounting requirements FIGURE 60. OPTIONS FOR INTEGRATION OF PV SYSTEMS ON GLASS ROOFS For both BAPV and BIPV integrated in facades (Source: ECN). are several requirements regarding the safety a) flat roof. and good functioning of the PV system. - When mounting PV modules on existing building, the load bearing capacity of the structural elements of the facade. - The fixation of the modules should be strong enough to resist to weather factors as wind, hailstorms and snow. - The joints of warm facades should ensure good air and water tightness. There are b) sloped roof. special modules that ensure good insulation, follow strictly the recommendations of the producer! - Avoid the installation of modules on the ground floor, close to paths and other areas accessible to public in order to avoid damages.
3.4. Glass roofs, shading systems c) individual construction , roof membrane and other applications
3.4.1. Glass roofs Glass roofs from PV modules are an excellent choice. They can be integrated on flat roofs, sloped roofs or individual construction.
The following figures show possibilities for integration of glass roof from PV A very nice application of glass roof is the PV modules.(ECN) parasol. A roof construction as a parasol covered with PV modules reduces heat load and improve the comfort of the building. The PV parasol can be with or without water- retaining function, depending on the needs of the building. (ECN) The following figure shows an example of PV parasol with water-retaining function and without water-retaining function
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FIGURE 61. FIGURE 62. OPTIONS FOR INTEGRATION OF PV SYSTEMS ON PARASOL EXAMPLE OF GLASS ROOF WITH PV MODULES (Source:SEC) (Source: ECN). a) PV parasol with water-retaining function.
b) PV parasol without water-retaining function.
3.4.2. Shading devices
Shading devices are ideal for integration of PV modules in buildings. This solution is suitable both for new and existing buildings. Shading devices with PV modules are an excellent combination of:
• Passive cooling,
• Daylight control, as the best inclination for PV modules is the same as for providing most shadow,
• Electricity production.
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There are several options for building They can be fixed or movable. integration of shading devices from PV FIGURE 64. modules. PV SHADING (Source:ECN) They can be independent from the building envelope, incorporated in the building envelope as a curtain wall, or an additional element of the building as a canopy.
FIGURE 63. OPTIONS FOR INTEGRATION OF PV SYSTEMS IN SHADING DEVICES (Source: ECN). a) PV shading devices independent from the building envelope.
The following figure shows an example of b) PV shading devices incorporated in the building envelope as installation of PV shading curtain on the a curtain wall. façade. FIGURE 65. INSTALLATION OF PV MOVABLE SHADING ELEMENT (Source:SST)
c) PV shading devices additional as a canopy.
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3.4.3. Other applications FIGURE 66. COMBINED PV-SOLAR TERMAL FUNCTION (Source:ECN) PV modules can be used for other applications as ensuring natural lighting. a) Air medium PV on sky lights should be installed on the south side of the element. They will ensure a good light with the necessary sun protection for the premises in the building. For sky lights should be used opaque cells laminated in double glass with a space of 1-3 cm. between the cells. PV modules on sky lights ensure diffuse or tempered light with interesting shadow patterns.
The integration of PV modules in buildings is widely used for passive solar design. Elements from PV modules as awnings, b) Water medium double façade and glass roofs prevent the building from overheating. Transparent PV modules integrated in the building envelope improve the indoor climate and ensure access to daylight.
An innovative solution is the combined function PV-solar thermal. (ECN)
The benefits of hybrid collectors with medium air or water are: PV modules can be integrated in many • Cooling the PV element improves its constructions as: efficiency. • Bus stops, • Heat from thermal element can be used • Car parks, for hot water and heating. • Roofs of railway or bus stations,
• Sound barriers, This solution is attractive when the roof space • Information boards, is limited. • Street lights, etc.
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FIGURE 67. ROOF OF BUS STOP AND CYCLE PARK WITH PV MODULES (Source:SEC)
3.5. Design parameters and performance factors
3.5.1. Location and urban planning The efficiency of a PV system depends on the following factors:
• The amount of solar radiance on the site, • The orientation and tilt of the modules, • The quality of the modules and inverter.
An appropriate urban planning is the first step for a successful implementation of PV installations in buildings and other urban constructions. If the site does not have the appropriate orientation, the south oriented slope of the roof and the facade might not have enough space for a larger PV installation.
Even the surrounding vegetation should be
planned correctly. Trees situated close to the southern facade of a building will overshadow the building.
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The following pictures show several planning c) possible solutions, but not the best. solution for one site. The first picture illustrates the best solution, as all PV modules are foreseen to be installed on south roof slope. The second picture shows also a good solution with two long buildings oriented to the south and two small oriented to the east The last two pictures illustrate possible solutions, but not the best.
FIGURE 68. PLANNING SOLUTION FOR ONE SITE (SOURCE ECN). a) best solution, as all PV modules are foreseen to be installed on south roof slope.
3.5.2. Orientation and tilt The benefits of a PV system depends on a great extend on the orientation and tilt of the PV modules. b) a good solution with two long buildings oriented to the PV Production depending on inclination and south and two small oriented to the east. orientation of several facades or roofs: Optimum Orientation = South Optimum Inclination angle = Latitude(º) – 10º (over 30⁰ in Europe) PV modules on facades are 30% less efficient than PV modules on roofs. The following table gives the factors for calculation losses from PV efficiency depending on the orientation and tilt of the modules.
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TABLE 20. FACTOR OF ORIENTATION AND TILT (Source:SEC )
Factor for calculation losses at a given orientation and tilt Tilt
90⁰ Orientation 0⁰ 30⁰ 60⁰
0,93 0,90 0,78 0,55
East
0,93 0,96 0,88 0,66
South-east
0,93 1,00 0,91 0,68
South
0,93 0,96 0,88 0,66
South-west
0,93 0,90 0,78 0,55
West
Best orientation Very good orientation
Good orientation To be avoided
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3.5.3. Shading To avoid self-shading you should examine the building geometry and details like: Even with the best orientation and tilt foreseen for the PV modules, the system can • Satellite receivers on roofs, be very inefficient if shading is not taken into • Chimneys and shafts, account. • Skylights and other higher parts, • Hanging elements. We should examine two types of shading issues: FIGURE 70. SELF-SHADING (Source:ECN) • Shading from surrounding buildings, trees and topography and • Self-shading.
Shading by surrounding landscape and buildings should be taken into consideration for:
• winter and morning and evening sun, • growth of the trees, • planning further erections of new buildings.
To avoid this problem dummy PV modules or by-passes should be foreseen for shaded areas. Be careful, shaded diffuse light can strongly affect the efficiency of the PV installation!
FIGURE 69. SHADING FROM TREES (Source:ECN) To avoid self-shading the solution is the same as for shading from surrounding elements: install dummy PV modules or by-passes.
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3.5.4. Construction requirements The construction of the system will also be exposed to strong wind that can lead to The planning stage twisting, vibrations and additional dynamic The structure of the elements of the building and static load. The system should be envelope where will be mounted PV modules calculated accordingly the building legislation should be calculated accordingly the regarding wind load in the county. expected additional load of the installation. In new building this should be done at the planning stage. For existing buildings it is The construction stage advisable to check the condition of the The installation of PV modules should be structural elements of the roofs and facades. waterproof regarding the cabling. In case of Follow the requirements of the building BIPV they should ensure a total regulations. waterproofing of the building envelope. Be careful to use the right modules and At planning the construction works, the materials! accessibility of the roofs and facades for mounting the elements of the PV installation The installation of BIPV should also ensure air should be examined, as well as the tightness according to the requirements of accessibility for maintenance. building regulations for facades and roofs. The fixation of the PV modules should be Be careful, PV modules are fragile! Avoid calculated to be strong enough to meet the walking on them. load from snow, ice and hail. In countries with heavy snowfall tilt angle of FIGURE 71. PV modules should be at least 45⁰. The DON’T WALK ON PV MODULES (Source:ECN) modules should have a smooth surface to allow snow slippage.3
When wiring the system have in mind the safety. Prepare carefully the cabling and cable penetration. Finish the installation with connection in inverter room and to the grid.
3 Education and training material for architects, Energy Research Centre of the Netherlands (ECN) PVTRIN Training course- Solar installers handbook 79
FIGURE 73. 3.6. Examples from the residential INTEGRATION OF PV MODULES IN EXISTING BUILDING (Source: SEC ) sector PV modules can be integrated at building retrofit in roofs and facades. The most typical example of PV integration in buildings is PAPV on roof of existing buildings. They usually are installed on roofs covered with tiles as additional element (they are not integrated in the structure).
FIGURE 72. D PV ON ROOF (Source:ECN)
When PV modules are installed on roofs and facades of new dwelling buildings, they are usually fully integrated (BIPV). The PV modules are elements of the design concept of the building. The following pictures illustrate examples from the Netherlands. The Waterkwartier Nieuwland (Water district New Land) is known as a 1 MW (megawatt) project, as many homes have
been fitted with solar panels for electricity production.
FIGURE 74. The following picture illustrates the WATER DISTRICT NEW LAND, BIPV ON ROOFS OF SINGLE- FAMILY HOUSES (Source: SEC ) integration of PV on facades of an historical building in Aarhus, Denmark. In the facades are mounted also solar thermal collectors for domestic hot water and heating. The PV modules and solar collectors are installed on the facade oriented to the inner yard of the building, the main facade is not affected and keeps its historical aspect.
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FIGURE 75. W WATER DISTRICT NEW LAND, BAPV ON FACADE OF MULTI- FAMILY DWELLING BUILDING (Source: SEC )
The residential area in Amersfoort is an unique project in Europe regarding not only the grid-connection of the solar panels installations, but at the same time using the south-orientation, daylight, various architectural application of solar panels and natural illumination.
FIGURE 75.FIGURE 78. RESIDENTIAL AREA AMERSFOORT, BIPV ON ROOFS OF SINGLE- FAMILY HOUSE (Source: SEC )
FIGURE 76. W WATER DISTRICT NEW LAND, BIPV ON ROOFS OF SEMI- DETACHED SINGLE-FAMILY HOUSES (Source: SEC )
FIGURE 77. W WATER DISTRICT NEW LAND, BAPV ON ROOF OF SINGLE- FAMILY HOUSES (Source: SEC )
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FIGURE 79. R ESIDENTIAL AREA AMERSFOORT, BIPV ON ROOFS OF KINDER GARDEN (Source: SEC ) FIGURE 76.FIGURE 81. PV MODULES ON THE FLOATING ISLANDS ON THE LAKE TITICACA (Source: SEC )
FIGURE 80. R ESIDENTIAL AREA AMERSFOORT, BIPV ON ROOFS OF CAR AND CYCLE PARCS (Source: SEC )
The above examples show that PV modules will be very soon an integral part of urban landscape. They can be everywhere, on the roofs, facades, shadings devices, shelters on bus stops and car parks, etc. But PV systems are also very important for remote areas and locations where it is not possible to ensure a grid connection. Such areas are the floating islands on the lake Titicaca in Peru. The PV modules are the only possible source of electricity. They can secure enough energy for computers (even in the school), TV and some other small consumers. PVTRIN Training course- Solar installers handbook 82
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3.7. Exercises 3.7.2. BIPV and BAPV on roofs 1. What should be taken into account when 3.7.1. Mounting and building installing PV modules on flat roofs? Choose integration options the three right aspects from the list below. 1. BAPV and BIPV are PV modules installed in • The structure of the roof buildings only for principal energy source. • The thickness of the thermal insulation • The orientation of the building
True False • The type of modules • The elements of the roof as chimneys, skylights, etc. 2. What should be checked according to 2. What is the difference between BAPV and building regulations when PV modules are BIPV? installed on existing buildings?
• BAPV can be installed only on roofs, • The covering material of the roof while BIPV can be installed on roofs, • The load bearing capacity of the facades, shelters and other structure • BAPV are used only as additional energy • The insulation materials source, while BIPV are used both as 3. Should we take care of the water-proofing additional and principal energy source membrane of the roof when installing PV • BAPV are fixed over the existing modules? elements of building’s envelope, while
BIPV are photovoltaic materials used Yes No instead of conventional building materials 4. What is the minimal distance between the - rows of PV modules on flat roofs in order to 3. Where BIPV and BAPV can be installed? avoid shading?
• Only in dwelling buildings • 1/3 of the height of the structure • In all type of buildings and in urban • 1/4 of the height of the structure structures as bus shelters • 1/2 of the height of the structure • Only in industrial and dwelling buildings 5. BAPV are more suitable for: 4. There are three key components of a grid- connected system, choose the right ones. • Installation on existing buildings • Installation on new buildings • The facade of the building • Installation on flat roofs • The PV modules 6. How to avoid over-heating of PV modules • The inverter on pitched roofs? • The roof • • The current meter Covering the whole roof • • The public grid Using PV tiles • • The windows Ensuring 5-10 cm. between the PV element and the roof’s covering
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3.7.3. BIPV and BAPV on facades 10. What is the difference between cold and warm facade? 1. Can PV modules be fully integrated and cover the whole of the facades? • Warm facades are south oriented while cold facades are north oriented
Yes No • Warm facades have additional thermal insulation, thicker than on the cold facades 2. Can be PV modules fixed on the balconies? • Warm facades are these facades when Yes No the PV modules are integrated in the structure of the facade, while cold
facades are these facades where PV 3. Can be PV modules fixed as additional glass modules are an additional element, like facade? a second “skin” of the building • Yes No 11. Should we check the load bearing capacity of the structure of the facade of an 4. Are BAPV cheaper? existing building? Yes No Yes No 12. Should we take into account the weather factors as wind and hailstorm when fixing the 5. Should we ensure air tightness between modules on facades? the joints of BAPV on facades? Yes No Yes No
13. Should we ensure air and water tightness 6. Are BAPV on facades easier for of joints between the modules? maintenance? Yes No Yes No
14. Is it recommended to install modules on 7. Can BAPV act as additional thermal the facade of ground floor? insulation of facades? Yes No Yes No
8. Is it easier to ensure cooling of BAPV than of BIPV? 3.7.4. Glass roofs, shading systems and Yes No other applications 9. Do BIPV give better opportunities for good 1. Can we cover a whole roof with PV architectural solutions? modules?
Yes No Yes No
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2. A glass roof with PV modules reduces heat 4. In the following table rate the tilt and load and improve the comfort of the building. orientation of PV modules from 1 to 4 (1 – the best orientation and tilt, 4- the worst). Yes No
Tilt 3. Are shading devices appropriate for installation of PV modules? • Yes, they could be 90⁰ • Yes, they are very appropriate • No 0⁰ 30⁰ 60⁰ • 4. Can we combine PV and solar thermal Orient functions? ation Yes No
5. Can be PV modules integrated in sound barriers, street lights, information boards? East
Yes No
South- 3.7.5. Design parameters and east performance factors 1. What factors affect the efficiency of a PV system? • The amount of solar radiance on the site • The type of building South • The orientation and tilt of the modules
• The grid connection • The behaviour of the occupants of the building - The quality of the modules and inverter South- 2. Do we need appropriate urban planning for west a good efficiency of PV systems in buildings?
Yes No
3. Should we take into account the surrounding trees? West Yes No
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5. Should we check for further erection of 7. What tilt angle should have PV modules new buildings around our building? installed in regions with heavy snowfall?
Yes No • 30⁰ • 45⁰
• 60⁰ 4. Should we take into account satellite receivers and sky lights on the roof? 8. Can we step on the modules? Yes No Yes No
5. Can we avoid problems with shading 9. Should the installation be waterproof through dummy modules and by-passes? regarding the cabling? Yes No Yes No
6. At planning stage of the installation we should take into account:
- The accessibility of the roof
Yes No
- The accessibility of the facade
Yes No
- The load bearing capacity of the structure of the building
Yes No
- The surrounding temperature
Yes No
- The traffic
Yes No
- The load from snow, wind, ice and hail
Yes No
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INSTALLATION – SITEWORK 4
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• Removing the hazard, using different 4. INSTALLATION – SITEWORK substances or work processes.
4.1. Working safely with PV 2. If risks are not avoidable or preventable, how can risks be reduced to a level at As an installer of PV systems you are which the health and safety of those responsible not only for your own health and exposed is not compromised. The safety, but also for the health and safety of following additional general principles of your customers and anyone else who might prevention should be followed: be affected by your actions. You are also responsible for the long-term safety of the PV • Combating the risk at source. systems you install. Hence it is your • Adapting the work to the individual, responsibility to identify all of the risks especially as regards the design of work associated with your PV installations and to places, the choice of work equipment take appropriate actions to minimise and and the choice of working and control these risks to an acceptable level. production methods, with a view, in particular, to alleviating monotonous Every installation is different and so it is not work and work at a predetermined possible for this handbook to provide a work-rate and to reducing their effect comprehensive and definitive list of safe on health. working practices and system design • Adapting to technical progress. processes that you should apply for all • Substituting the dangerous by the non- installations. However, this section does dangerous or the less dangerous provide information on potential hazards (replacing the machine or material or associated with the installation and operation other feature that introduces the hazard of PV systems that you may wish to consider by an alternative). when preparing method statements and risk • Developing a coherent overall assessments for the installation of PV prevention policy which covers systems. (OHSA, 2011) technology, organization of work, working conditions, social relationships and the influence of factors related to 4.1.1. Safe Working Practices the working environment. The “Framework Directive” Council Directive • Giving collective protective measures 89/391/EEC of 12 June 1989 on the priority over individual protective introduction of measures to encourage measures (e.g. controlling exposure to improvements in the safety and health of fumes through local exhaust ventilation workers at work and the legislation to rather than personal respirators). implement it in the Member States contains a • Giving appropriate instruction to hierarchy of control measures to be followed: workers. (OSHA, 2011)
1. Are risks preventable or avoidable? Is it possible to get rid of the risk? This can be done, for instance, by: 4.1.2. Potential hazards
• Considering whether the task or job is The installation of PV systems presents a necessary. combination of hazards which you are unlikely to have encountered during previous PVTRIN Training course- Solar installers handbook 88
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building work. These include manual no one gets hurt or becomes ill. A risk handling, working at height and the risk of assessment involves identifying the hazards electric shock. present in any undertaking (whether arising from work activities or from other factors, European and national requirements for safe e.g. the layout of the premises) and then working practices in the workplace are widely evaluating the extent of the risks involved, available. (e.g. http://osha.europa.eu and taking into account existing precautions. www.hse.gov.uk ) and so are not all included here. However, there are many PV specific The results of a suitable and sufficient risk hazards that should be considered when assessment should help users choose which preparing a method statement and risk good practice measures are most assessment for the installation of a PV system appropriate.” examples of which are presented below. A risk assessment should always be carried Please note that due to the continuously out before good practice is applied in the changing nature of PV installations the workplace. It has to be adapted to individual following information is not a definitive list, it circumstances and needs. EU-OSHA cannot has no legal standing and no liability is be held responsible over how the information accepted for its use. is implemented. When preparing method statements and risk More information on risk assessment can be assessments consideration should be given to found at OSHA riskassessment, 2011 the equipment required to ensure the safety of the installer (i.e. personal protection equipment) and the safe operation of the 4.1.3. Safety with electrical installations installed system (i.e. measurement and testing equipment). 4.1.3.1. Working with electrical circuits Preventing electric shock by working on de- energized circuits is a key to electric safety. The importance of risk assessment. Following are some items to consider when It is most important that before good practice working on electric circuits. information is implemented in the workplace, a suitable and sufficient assessment of the - Always de-energize circuits before hazards and risks in the workplace must be beginning work on them. carried out. This assessment should consider - You can’t get shocked by a de-energized all the risks and hazards in the workplace to circuit. Unfortunately, many electric ensure that there is a real reduction in the accidents have been caused by assumed exposure of workers and other to harm ‘dead’ circuits. Working safely on circuits rather than merely replacing one risk with includes testing them for hazardous energy another. prior to working on them. The following is one simple description of a - Use a meter or circuit test device such as a risk assessment. “A risk assessment is nothing current clamp to ensure the circuit is dead more than a careful examination of what, in prior to working on it. your work, could cause harm to people, so that you can weigh up whether you have - Implement circuit lock and tag out rules taken enough precautions or should do more - Lock out the power on systems that are to prevent harm. The aim is to make sure that capable of being locked out. Remember PVTRIN Training course- Solar installers handbook 89
that the lock out tag is not for the person removed – always follow manufacturer’s that you are aware of and that knows you directions and check the equipment you are working on the electrical circuit – it’s for are working on for specific operation and the person you don’t know and that doesn’t safety information. know you are working on the circuit. You • must notify all affected persons. 2. The only method of ‘turning off’ a solar - Tag out all circuits that you’re working on at array is removing the ‘fuel’ source – the points where that equipment or circuit can sun. If needed, cover the array with an be energized (OSEIA,2011). opaque cover that blocks sunlight to prevent a solar panel from generating
electricity. 4.1.3.2. Working with solar electric systems 3. Small amounts of sunlight can produce a
voltage potential and shock or arc-flash Electricians are familiar with electricity hazard coming from the utility side of the meter. With solar electric systems there are two - Voltages can be present even in very low sources of electricity: the utility and the solar light conditions. While these voltages electric system. may not be enough to operate the inverter, the potential voltages are Turning off the main breaker doesn’t stop a enough to produce a shock to an solar electric system from having the capacity unsuspecting installer. Surprise shocks to produce power. Electricians are used to can cause injuries directly or cause a fall isolating the ‘load’ from the power source from a roof or ladder. (usually with a breaker or other disconnect switch) and then they proceed to work on - Prior to working on a string of solar PV that ‘safe zero energy load’. With a solar panels, if you’re going to be connecting electric system you work on the power or disconnecting circuits, you should source itself (the PV panels or associated disrupt the current path by wiring) – this is fundamentally different than disconnecting the DC disconnect switch. working on a ‘safe load’ and you must keep Tag and lock out the circuit using this in mind. Even low light conditions can standard procedures discussed in the create a voltage potential that can lead to a previous section. shock or arc-flash. A surprise shock delivered • at the wrong time could cause a fall from a 4. Grid tied solar systems have two energy roof or ladder. sources to consider Following are some issuess to consider when - Shutting off the main circuit. Breaker working with solar electric circuits: does not affect the potential output of a
solar PV array – even if the inverter shuts 1. Follow the procedures listed in the off. It’s important to remember that previous section on working with electrical opening (turning off) the main breaker systems. does not shut off the power source from - Note that PV inverters may have the solar array. Wires from the PV side significant capacitors that could hold a of the circuit can still have a voltage charge after the power source is PVTRIN Training course- Solar installers handbook 90
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potential that can deliver significant - Always open the DC Disconnect Switch current even in low light conditions. prior to working on a solar PV system. - Disconnect switches can isolate the solar PV array but they do not shut the power Use a current clamp to check for off. Remember that if you open the DC hazardousenergy prior to working on a PV disconnect switch, the line from the array (OHSA, 2011). solar PV array can still have voltage potential on it. This is similar to the FIGURE 78.FIGURE 83. voltage potential present on the utility CURRENT CLAP (Source: OSEIA,2011) side of the line after the main breaker is opened. Treat the wiring coming from the solar PV array with the same caution you treat the utility power line. A residential PV array can have up to 600 VDC potential.
5. An electric arc-flash hazard exists while adding or removing a series of solar PV panels
FIGURE 77.FIGURE 82. ARC FLASH HAZARD (Source: OSEIA,2011 )
4.1.3.3. Working with batteries Working with battery back-up systems can be the most dangerous part of solar electric installations and maintenance. Batteries can be dangerous! Make sure all employees working with batteries understand the dangers and safety - NEVER disconnect PV module codes relevant to battery systems. connectors or other associated PV wiring - Refer to NEC and manufacturing guidelines under load! for issues pertaining to proper handling, - While adding or removing a series of installation, and disposal of batteries. solar PV panels, if a path for current is - Typical batteries are lead acid. Both lead completed or the string was under load, and acid are harmful chemicals. Lead is an electrical arc can occur across the known to cause reproductive harm and acid wire junction. The energy from the can cause severe burns. bright arc-flash can cause severe burns. - Care should always be taken to prevent Another hazard is the surprise arc blast arcing at or near battery terminals. Always causing you to lose balance and fall off a open the Main DC disconnect switch roof or ladder. between the batteries and the inverter prior to servicingor working on the battery bank.
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- Battery banks can store voltages with very You don't need to overcomplicate the high current potential. These higher process. The risks for working at height are potentials can create electrical arc hazards. usually well known and most necessary Metal tools and personal jewelry can create control measures are easy to apply. arcing on batteries that lead to severe burns The law does not expect you to eliminate all or battery explosions. Remove personal risk, but you are required to protect people jewelry and use only appropriate tools by minimising risk as far as 'reasonably when working on batteries. practicable'. - When working on batteries it is recommended that eye protection be worn. If you have to work at height - Dead batteries are considered hazardous - Use an existing safe place of work to access and must be recycled properly. (OHSA, work at height - don't cut corners, if there is 2011) already a safe means of access such as a permanent stair and guard railed platform use it. 4.1.4. Security provisions for work at - Provide or use work equipment to prevent height. falls, such as scaffolding, mobile access towers or mobile elevating work platforms When planning work at height you need to (MEWPs) which have guardrails around the carry out a 'risk assessment'. This should working platform. supplement your overall health and safety - Minimize distance and consequences of a risk assessment. fall, for example by using a properly set up TABLE 21. stepladderP or ladder within its limitations LANNING WORK AT HEIGHT (Source: OHSA, 2011) for low level, short duration work only.
4.1.4.1. Mobile Accesses
Mobile tower You must be competent in erection and dismantling of mobile scaffolds; and you must always read and follow the manufacturer's
instruction manual and on no account attempt use the equipment beyond its limitations.
Commonly referred to as mobile access
towers or mobile scaffold towers, these structures are manufactured from prefabricated components where the principal structural materials are aluminium alloys or fibreglass. Wheels or feet of the tower must be in contact with a firm surface. Outriggers should be deployed as specified by the manufacturer. PVTRIN Training course- Solar installers handbook 92
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FIGURE 79.FIGURE 84. FIGURE 80.FIGURE 85. MOBILE TOWER(Source: OHSA, 2011) MOBILE ELEVATING WORK PLATFORM (Source: OHSA, 2011)
Mobile Elevating Work Platforms (MEWPs) They can provide a safe way of working at height, because it: Leaning ladder • Allow the worker to reach the task quickly and easily. Ladders should be used for low risk, short duration work. • Have guard rails and toe boards which prevent a person falling. Ladders are classified for type of use: • Can be used in-doors or out. • EN 131 is for trade and light industrial • MEWPs include cherry pickers, scissor use; lifts and vehicle-mounted booms. • BS2037/BS1129 Class 1 for heavy duty
and industrial use; and BS2037/BS1129 Class 3 for domestic use.
Manufacturers must always supply information about the specification of their ladders and provide information such as maximum working load. People should only use a ladder, step ladder or stability device if they are competent. Users should be trained and instructed to use the equipment safely.(OHSA, 2011) PVTRIN Training course- Solar installers handbook 93
FIGURE 81.FIGURE 86. - Head protection (e.g., hard hats, helmets, LEANNING LADDER (Source: OHSA, 2011) hats). Hard hats are required if there is a risk of objects falling onto a person or a risk of hitting your head on an object. For example, if someone is working on the roof above you, you need to wear a hardhat. - Protection of extremities (e.g., steel-toed shoes, other protective footwear, safety gloves, latex gloves, kneepads). - Respiratory devices (e.g., respirator, dust mask). These are especially important if you are working around lead paint or asbestos. Masks may be warranted in attic spaces around insulation. - Hearing protection (e.g., ear plugs, canal caps, ear muffs). - Protective clothing.
4.1.6. Fire protection 4.1.5. Safety equipment The fire resistance rating of the modules is The objective of the Personal Protective Class C. Equipment is to protect employees from the The installation of a PV system on a building risk of injury by creating a barrier against may affect fire safety. workplace hazards. Personal protective equipment is not a substitute for good • For roof application, the PV system must engineering or administrative controls or be mounted over fire resistant roof good work practices, but should be used in covering rated for the application. conjunction with these controls to ensure the • Do not install or use PV modules near safety and health of employees. hazardous locations with flammable gases.
Employers should provide and to pay for In case of a fire in building YGE PV modules Personal Protective Equipment (PPE) required on the roof are likely to produce dangerous for the worker to do his or her job safely. The DC voltage, even in the cases of: employer must also ensure employees use and maintain PPE in a sanitary and reliable • Low light intensity, modules being condition. When employees choose not to disconnected from the inverter. comply with PPE rules it usually indicates a • Modules being partly or entirely failure of the safety management system. destroyed. • Wiring being compromised or destroyed. PPE can include the following:
- Eye and face protection (e.g., safety goggles, glasses, face shield, visor). During and after a fire stay away from all elements of the PV system, inform the fire PVTRIN Training course- Solar installers handbook 94
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brigade about the particular hazards from the - PV modules produce electricity when PV system. Have your installer perform the exposed to daylight and cannot be switched necessary steps to bring the PV system back off. This means that the installation of PV into a safe mode.(YINGLI,2011) systems often requires working on live electrical circuits.
- PV modules produce d.c. electricity which 4.1.7. Other Risks behaves differently from a.c. electricity. For - PV modules are often large (2m2 or more) example a d.c. arc can propagate over an air and heavy (>50kg) and so require particular gap of several mm (depending on voltage) care when being lifted or manipulated and continue until the voltage is removed particularly when working at height. or the air gap increased. Such arcing may cause fires and/or significant damage. - PV modules impose both static and wind loads. The mounting structure should be - The fault current in PV module wiring is assessed to ensure it is capable of little more that the normal operating withstanding these loads. current. This often means that fuses and circuit breakers cannot be used to provide - Bracketry or mounting frames should also protection. be adequately protected from corrosion and be capable of supporting the static and - A PV installation can develop lethal d.c. wind loads, and must be adequately voltages if inadequately earthed ballasted or fixed to a suitable structural - PV systems may be described as ‘low member. voltage’ even if they generate up to 1500V - Where it is necessary to create penetrations between conductors. 20V d.c. touch voltage in the skin of the building (e.g. during the is normally considered sufficient to give a installation of cables or of an integrated PV risk of shock. system) adequate steps should be taken to - The risk of shock is greatly increased if a PV ensure the building’s fire resistance and module or installation is damaged. weather tightness is maintained. - To maximise efficiency PV modules are - Unlike glazing units for roofing or vertical generally installed in unsheltered places. cladding PV modules are often Thus cold, wind and rain may present a manufactured using laminated toughened hazard during installation and maintenance. glass. This means that the glass component - Parts of PV modules may reach high will not shatter if damaged and could fall as temperatures (ca. 80C) during normal a single piece. operation. - The edges of PV modules, particularly - The surfaces of PV modules can reflect a where glass edges are exposed, may be significant proportion of incident sunlight sharp. which could cause eye damage. - Although not sufficient to cause harm
during installation or maintenance, some PV products contain cadmium which may For further information and guidance see the present a toxic dust hazard should the chapter 9. Further reading.. product be crushed during disposal.
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4.2. Installation plan be coiled as this will reduce the cable’s ability to dissipate heat, and could also lead to The installation and commissioning phases of inductive voltage spikes being transmitted to the project provide the means to implement the inverter on disconnection of the array or the good design practices discussed in section a string. 2. Whilst perhaps not impacting directly on the However, the use of both high quality initial performance of the system, the quality components and installation procedures is of the physical installation of the system, not just a matter of adherence to regulations particularly the PV array, can influence the The quality of the system installation has a long-term performance of the system and its strong influence on the ongoing performance costs. Poor fixing of array components can of the system and in meeting expected result in damage to the array during adverse system lifetimes and output levels. weather conditions, resulting in loss of Having selected appropriate components for output and the need to repair or replace part the PV system, it is important that they are of the array. It can also lead to damage to installed in accordance with the other parts of the roof, in some cases manufacturer’s recommendations, especially affecting the weatherproofing. in terms of required fixings, ventilation, The commissioning procedure allows a check operating temperature range and safety of system performance at the time of aspects. Failure to adhere to the correct installation. Certain aspects of the operating conditions can lead to poor commissioning will be discussed in terms of performance levels, reduction of lifetime of their relation to system performance issues. components and even failure of the system in (DTI,2006) some cases. During the planning stages of a photovoltaic Attention should be paid to minimising cable installation, you need to take into account lengths and, particularly, to ensuring that all the provisions, transportation and inventory. connections are correctly made and In general, the installation of a photovoltaic protected. Whilst it may not affect the initial park includes answering the following performance of the system, a poor questions: connection can become more influential with time and lead to performance reduction in What, How and When (to do the) assigned the long term. tasks --> Doing Performance losses due to poor connections These questions need to be resolved during can be significant but are generally time- the planning stages of assembly, regardless of consuming to identify and rectify, especially if the the size of the installation. In this way, we they are within the array. It is much better to eliminate unexpected factors, setbacks, ensure the quality of the connections at the improvisations and dangerous situations. time of installation than to have to address this issue later during system operation. All of the components of an installation come Excess cable should be avoided wherever with assembly instructions, risk assesments, possible. Where a small excess is necessary etc. from the corresponding manufacturer. (such as when allowing for a system You should follow these best practices to component to be moved for inspection insure proper execution of a reliable and without disconnection), the excess should not secure assembly. PVTRIN Training course- Solar installers handbook 96
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All basic operations included in the assembly customer and their needs, you need to process should be clearly defined, with adhere to the following action plan which estimated duration and time constraints includes: feasibility study, annual report, required for each operation; that is, deadlines blueprints, list of conditions, budget, safety for each stage from the exact moment of plan, etc. In this way, and with the pertinent execution. These tasks should figure inside information available, the installer will be an established timeline. (Gantt diagram or able to perform the installation in the allotted similar) (ASIF, 2002) time for the project and meet the applicable 19 quality standards.
4.2.1. Work Sequences The sequence of work the installer should Feasibility Study follow begins by planning all of the personal Before undertaking the project itself, the and material resources necessary to designer collects in a document called accomplish the installation properly. Feasibility Study, taking into consideration The on-site mounting process consists of the the needs of the customer and type of following steps (TKNIKA): installation, must: a) Mounting structures. - Evaluate the energy needs and interests of the user in order to determine the most b) Mounting the photovoltaic field appropriate type of installation and its c) Connecting the photovoltaic features. modules. - Determine the potential level of solar d) Mounting the corresponding power generation of the region where the distribution board. installation is to take place in order to quantify the feasibility of the application of e) Layout of tubes and conduit. solar power. To this end, different means f) Connecting components. should be used: charts or available statistics, on-site measurements, use of g) Running and testing the system computer systems, etc. - Formalize and make solar installation proposals official in accordance with the 4.2.2. Technical documentation energy needs and interests of the customer. An authentic project should always include the applicable legislation regarding the The finished product will be an economic and installation, taking into consideration all technical study of the proposed installation technical as well as environmental aspects. In for the customer's consideration. (TKNIKA) this sense, there is a great distinction between photovoltaic systems and those which are connected to the power grid, Report especially since the latter involves a much more extensive legal procedure. The objective of the report is to explain the purpose of the project (what you want to do) When embarking on a project after receiving as well as the decision-making process the appropriate information from the followed and the justification of each choice PVTRIN Training course- Solar installers handbook 97
made, providing details – if possible – of the or installer and the property management: entire procedure. At the same time, the provisional reconsideration, property report indicates how each part of the assessment, liens, form of payment, technical system designed works, etc. In guarantees, etc.20 essence, it is a description of every step taken during the design phase of the project. 4.2.3. Technical drawings Depending on the type of project, the outline of the report may vary substantially, but in This section should include all of the drafts or general, the following phases of a grid- blueprints necessary for the installer to carry connected photovoltaic solar energy project out proper mounting procedures without any may serve as a useful guideline: doubt. Standard formats and symbology should be implemented when elaborating • Determining the project these drafts to avoid any possible margin of • Features of the PV installation error in interpretation: • Calculation of the components of the installation As a guide, some of the basic drafts to include • Estimation of total electric energy are: generated annually • Site Map • Calculation of approximate annual • Views of on-site location revenue • Floor plans of the project • Conclusion of the project 20 • One-line Diagram of Electrical Schematic • Addendums • Layout of component distribution
• Floor plan of electric power line Budget distribution • Etc. The budget indicates the economic cost of the execution of the project. This section As we mentioned before, the number and should include: the detailed cost of the type of drafts may vary substantially, different items of the materials, handiwork, depending on the project. In any and all transport, leasing of tools or machinery, as cases, such plans or blueprints must be well as any other component used to sufficient to insure proper execution of the accomplish the project. project beyond any doubt imaginable. It is advisable to make a chart indicating at (TKNIKA,2004) least the following items: Concept, quantity, unit price, and total amount.20 4.2.4. Tools and Equipment The tools and equipment at the disposition of the installer are not substantially different List of Conditions from those that any certified electrician This section will include all of the standards should have at their disposal. In any case, all to be met by the materials selected to of the necessary regulations contained in the execute the proposed project, the rules or corresponding legislation of each country guidelines the installer must follow for proper should be strictly followed. execution and completion of the project, and The installer must have at their disposition all all other administrative conditions that of the necessary components to assemble govern the relationship between the forman installations on roofs or building facades with PVTRIN Training course- Solar installers handbook 98
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the necessary safety equipment, having system, there are a number of PV specific received the corresponding training for their hazards that need to be addressed. use. These will be in addition to standard It is advisable to have access to the tools and considerations such as PPE (Personal machinery necessary for the transfer and Protective Equipment), working at height, lifting of photovoltaic modules and other manual handling, handling glass other materials to rooftops so these do not applications regulates in construction. constitute an excessive physical load for the PV modules produce electricity when installer. exposed to daylight and individual modules Lastly, the installer must have a compass and cannot be switched off. Hence, unlike most inclinometer available for the correct other electrical installation work, the positioning of the photovoltaic field. (Tknika, electrical installation of a PV system typically 2004) involves working on a live system.
4.2.5. Safety Plan As current limiting devices, PV module string circuits cannot rely on fuse protection for Depending on the scope of the project, the automatic disconnection of supply under safety plan can be less or more extensive, but fault conditions, as the short-circuit current is it should at least include: little more than the operating current. Once established, a fault may remain a hazard, • List and description of the works to be perhaps undetected, for a considerable time. performed • List of existing risks and detailed Good wiring design and installation practice precautions to be taken will serve to protect both the system • Description of safety rules to follow and installers and any persons subsequently list of any safety measures to be taken coming into contact with the system from an • Applicable regulations electric shock hazard (operator, owner, cleaner, service engineers, etc).
Undetected, fault currents can also develop This section is very important to insure the into a fire hazard. Without fuse protection to safe execution of the project with sufficient clear such faults, protection from this fire safety guarantees to avoid potential hazard can be achieved only by both a good accidents. Therefore, when elaborating the d.c. system design and a careful installation. plan, you must be clear and concise so that PV presents a unique combination of hazard the installer can easily understand and apply –due to risk of shock, falling, and the proper guidelines. 21 simultaneous manual handling difficulty. All of these hazards are encountered as a matter of course on a building site, but rarely all at 4.3. Electrical components once. installation While roofers may be accustomed to minimising risks of falling or injury due to 4.3.1. Mitigate electrical hazards manual handling problems, they may not be used to dealing with the risk of electric shock. When compiling a method statement and risk Similarly, electricians would be familiar with assessment for the installation of a PV electric shock hazards but will not be used to PVTRIN Training course- Solar installers handbook 99
handling large objects at heights. (OSHA, is recommended and permits the array frame 2011) to be left floating. Notes to terms used in the diagram below:
4.3.2. Install grounding system a) Isolating transformer: An isolating transformer is one in which the input and Connection of parts of a PV system to earth output windings are electrically separated by affects: double or reinforced insulation. • The electric shock risk to people in the While the hazards presented by an array vicinity of the installation frame reaching the system d.c. potential may • The risk of fire under fault conditions be significant, the potential fault/shock • Transmission of lightning induced surges current is typically much less than that from a • Electromagnetic interference mains fault. Hence it is the electrical separation of the mains from the d.c. using Proper grounding is an important safety an isolating transformer that is the key element of a properly installed PV system. determining factor when assessing the Grounding for PV systems is covered in NEC requirement for array frame earthing. 690(V). If the maximum system voltage of a b) ‘Equipotential Zone’: That is defined as a PV system is greater than 50V, then one zone in which exposed-conductive parts and conductor must normally be grounded. A extraneous-conductive parts are maintained recent provision, Article 690.35 that was at substantially the same potential by introduced in the 2005 NEC, provides details bonding, such that, under fault conditions, on how to install a compliant ungrounded PV the differences in potential between system of any voltage. This new provision is simultaneously accessible exposed and likely to cause some changes in the design of extraneous-conductive parts will not cause PV systems which are likely also to bring electric shock. ‘Extraneous-conductive parts’ changes in installation methods for these are conductive parts liable to introduce a systems. The key issue addressed in the 2008 potential, generally earth potential, and not NEC relating to Article 690.35 is the provision forming part of the electrical installation, to use “PV Cable” or “PV Wire” to meeting such as a water pipe, outside tap, a metal the conductor requirements for ungrounded downpipe – anything conductive that is array wiring. Several manufacturers offer connected to ‘Earth’ but not electrically part module leads with these types of conductors. of the system. Two types of connection to earth need c) PME: Protective Multiple Earthing – an consideration: earthing arrangement whereby the supply 1. Earthing of exposed conductive parts (eg. neutral and earth are combined into a single the array frame) conductor. Where the incoming supply is 2. System earths – where an array output PME, (the majority of domestic supply cable is connected to earth arrangements) the PME earth cannot be taken outside the equipotential zone. This is 1) Earthing of exposed conductive parts to prevent the potential shock hazard should The majority of installations will utilise class II the supply neutral ever be lost. modules, class II d.c. cables & connectors and be connected to the mains via an inverter with an isolation transformer. This approach PVTRIN Training course- Solar installers handbook 100
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FIGURE 82.FIGURE 87. ARRAY FRAME EARTHING DECISION TREE (Source: BRE et al, 2006).
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2) System earthing (D.C. Conductor earthing) The modules used will be certified for use as CLASS II protected equipment with an The bonding to earth of any of the current operating voltage up to 1000V. carrying D.C. conductors is not recommended. However as in the note All of the wiring used in the DC portion of the below, earthing of one of the live conductors installation will be done in keeping with this of the D.C. side is permitted, if there is at degree of protection, that is, double least simple separation between the a.c. side insulation. and the D.C. side, including in the inverter. Protection against indirect contact Note: In some countries it has been the In the AC portion of the installation, a practice to bond one part of the D.C. differential switch will be installed. conductors to earth (eg earth connection at midpoint of PV string or earthed D.C. In stand-alone installations with AC negative), or for performance reasons on consumption, a high´-sensitivity differential certain types of modules to earth the d.c. switch will be installed, with a characteristic positive. Due to the increased possible earth discharge of 30mA or 300mA. Depending on fault paths and possible problems with the type of circuit protected and response commonly available European inverter types time of 0.2 seconds. and internal earth fault detection circuitry, In grid-connected installations, along the such practice should only be made when electric power line connected to the low- unavoidable (any connections with earth on voltage grid, a differential switch with a the d.c. side should be electrically connected 300mA discharge will be installed, and with a so as to avoid corrosion) (DTI, 2006). response time of 0.2 seconds. The differential 4.3.3. Conduit switch to be installed will be automatically resettable, in case of discharge – the device The tubes and conduit used in PV installations resets itself in suitable conditions. must meet the official standards required by the corresponding country depending on the Protection against overcurrent type of installation to be executed: In the DC portion of the installation, suitable underground or in the open air, in a busy type gG fuses of the appropriate current will public place or remote locations, exposed to be installed allowing for the two poles to the elements or covered. Take into account connect and disconnect, positively or that many times these cable ducts are negatively. Instead of these fuses, resettable, exposed to the elements and subject to drawout, and protected fuses of the extremely high temperatures. (DTI, 2006) appropriate current and C curve allowing for the connection and disconnection of the two 4.3.4. Protections poles may also be used. These components The protections to be installed in a PV solar must be prepared for DC use. energy installation will be different according In the AC portion to the type of installation – stand-alone or In stand-alone installations thermomagnetic grid-connected, as indicated in the switches will be put in place to protect the appropriate diagrams. In general, the different circuits of the installation, as different types of protection to be installed indicated in the Low Voltage Electric are: Equipment Regulations (LVEER). Class II Protections PVTRIN Training course- Solar installers handbook 102
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In grid-connected installations, at the outlet 4.4. Equipment installation of the inverter, a thermomagnetic switch of suitable current-voltage and C curve will be 4.4.1. Photovoltaic module installed to allow for its isolation from the rest of the installation as a kind of protection When choosing a photovoltaic module, you against overcurrent and short-circuits. are going to use to configure a photovoltaic field, keep in mind the following: At the connecting point, where the photovoltaic installation and the electric • Type of photoelectric cell. power grid are connected, a thermomagnetic • Electrical features. switch of suitable current-voltage and C curve • Physical characteristics. will also be installed to allow for proper • Mounting. isolation of the photovoltaic installation from • the grid and protection against overcurrent Type of Cell (Photoelectric Cell): and short circuits. Nowadays there are different types of cells available (monocrystalline silicon, poli CLASS I PROTECTION crystalline silicon, amorphous crystalline, Grounding, of the metallic masses through a etc.) and various technologies to apply when specific conductor, called landline or PE. selecting the module to use to configure the photovoltaic generator.
4.3.5. Circuit Conductors Monocrystalline silicon cells have a good Conductors used in photovoltaic installations, performance thanks to their structural as in any other electrical installation, should precision. The manufacturing process is the be sufficiently spaced to avoid overheating same as they use in the electronic industry and excessive drops in voltage in different with a very high degree of purification, which powerlines, as indicated by statutory makes their production that much more regulations. costly. Conductors used in the DC part, will be classified as Class II (double insulation). You Poly crystalline silicon cells are similar to should use type RZ1 conductors monocrystalline cells, but they contain a (polyethylene reticulated insulation – XLPE - higher concentration of impurities, reducing with a polyolefin covering), running their output, although their cost-output temperatures above or equal to 90ºC and proportion is better than monocrystalline strain-voltages of 75071000V. silicon cells.
In the AC portion, just follow the dispositions indicated in the Low Voltage Electric Nowadays you can find monocrystalline Equipment Regulations (LVEER) for these panels that are very competitive in price with types of regulations. polycrystalline silicon cells and polycrystalline modules with a similar level of performance. Therefore, the choice of one or the other depends on market conditions.
Electrical Features:
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TABLE 22. force) , so you need to take the necessary ELECTRICAL FEATURES (Source: Tknika, 2004) precautions working with high voltage. On Parameters Description Units the other hand, you need to take into
Isc Short Circuit Amperes account the necessary means of Intensity transportation and assembly of the Ocv Open circuit Volts photovoltaic field, since this very often voltage Ip– Imax Peak Amperes includes assembly on rooftops or facades, Intensity of and due to their weight and dimensions, this primary input can be very complicated. current Vp – Vmax Maximum of Volts The two key aspects to take into primary output consideration when mounting the panels are: voltage • Wp – Wmax Peak Power – Watts The positioning of the panels. Maximum • Location. power • Joining the panels.
The strain-voltage of stand-alone installations Location is from 12, 24 or 48 volts. So it is essential to connect these modules in series or parallel in The weather conditions of any given locale order to obtain optimal voltage and intensity. are normally quite variable, and the proper functioning of the PV module will vary In grid-connected installations, the strain- accordingly. Therefore you must procure that voltage is much greater and depends on the the maximum amount of irradiance falls upon inverter used. In this case, it is important to the module, and that the temperature, at test the maximum number of modules that each and every moment, is kept to a we can connect in series, without causing any minimum. This is made possible by the damage. optimal choice of angle, direction and assembly of the photovoltaic modules, insuring that they are exposed to the Physical Characteristics: maximum amount of sunlight throughout The most important physical characteristics most of the day. are the dimensions and weight of the solar module that you will need to take into account when calculating the amount of Positioning the PV Modules space the photovoltaic field will occupy and Normally and under normal conditions, the to foresee any need for transport and anchoring of the modules to the structure assembly (heavy-tonnage vehicles, heavy takes place in two stages: connecting them in duty cranes, number of necessary personnel). series and in parallel, and the actual mounting of the structure. The modules are normally connected in angular metallic cross 4.4.1.1. Assembly: sections, in U-shape or square, which are When assembling the installation, you need screwed together, forming an integral panel to begin with the photovoltaic field, taking structure. into consideration that you cannot disconnect them and when they receive solar radiation they generate emf ( lectromotive PVTRIN Training course- Solar installers handbook 104
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FIGURE 83.FIGURE 88. The cross sections used to place the panels in UNION OF PHOTOVOLTAIC MODULES ( Source: Flickr, 2011) proper formation are also used to anchor them to the structure.
FIGURE 84.FIGURE 89. ATTACHING PV MODULES TO THE STRUCTURE. (Source: EKILOR)
Joining panels involves contact between two different metals (aluminum in the module and steel in the cross section). So we run the risk of electric shock. To prevent this occurence, you need to use insulation, such as nylon or non-stick washers which prevent FIGURE 85.FIGURE 90. such contact. ATTACHING PV MODULES TO THE STRUCTURE. (SOURCE: EKILOR) You should only use the modular holes of the panel specifically designed by the manufacturer, to insure the proper dismanteling of the frame surface and irreparable damages to the panel (such as glass breakage). The formation of the panels should adapt to the means necessary to avoid their deterioration, such as leaning modules against the package wrapping, which should be placed on a work bench or similar structure. Once the panels have been placed in proper Connecting PV Modules formation, you are now ready to position them inside the structure. This operation Once the panels have been properly placed in must be carried out by a number of operators formation, we are ready to join them and using the appropriate mechanical appropriately. apparatus such as cranes, pulleys, etc., The main objective is to prepare the electrical especially when the structure is located at a components of the PV Park; that is, to considerable height from the ground. prepare the main terminals, positive and negative, that defines the main circuit of the PV generator. These terminals are
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characterised by specific voltage and intensity selected one by one, according to their parameters during the design stage. tolerance. The intensity of all panels in series, as a whole, will be the same as each To prevent potential mistakes in joining individual panel. So each will be of the same panels, especially when dealing with PV cross section. (Tknika, 2004) (See section layers in series or in parallel configuration or 2.2.1) regulation, the use of technical drawings or outlines that take into account the position and wiring of modules, are highly Mixed Connections recommended. In this case, the desired voltage is achieved The wiring among modules should be carried by associating several modules in series out according to the existing connections of (ms). This structure forms a branch each and every module fuse box. The most connector of the generator. (See section common wiring is non-metallic, hose-like 2.2.1) flexible tubing. These must be perfectly adjusted to the fuse boxes. The desired intensity is obtained by associating a specific number of branch Normally for PV parks with a considerable connectors in parallel (Bn). number of modules, modular junction boxes In installations of defined power levels, you are usually used for in-series connections should position the maximum amount of among panels. (ASIF, 2002) modules in series to avoid sections of large wiring; as long as the operating voltage of the Parallel Circuits connected modules obliges. To obtain more intensity than a single When having to connect many branch module, you must connect several (one or connectors in parallel, the wires for each of more) modules in parallel circuits. (See them should be run to a central fuse box, and section 2.2.1) all of them connected in parallel. In this way, the section containing the conductors will All of these circuits must have equivalent always be the same for every installation. characteristics. For this reason, each one is This fuse box normally contains the circuit selected, one by one, according to their breakers, voltage loaders, the fuses and other tolerance. specific components of the design. The intensity of the sum of the panels in The use of this central control fuse box parallel circuits is equal to the sum of every facilitates maintenance and measurements to panel. So the circuit conductors will increase a great extent since you can easily access and their capacity in the same proportion of the locate the terminals of the distinct circuit number of panels that are connected. generators (rows of modules connected in parallel) all inside the same place. Series Circuits To obtain maximum voltage for each module, you need to connect several (two or more) in series. It is extremely important that every module possesses the same voltage - current characteristics. For this purpose, each one is
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4.4.2. Inverter interval to the tolerances allowed by regulation. There are different classifications in Inverters. Ones depending on the location in the Strain-Voltage: Photovoltaic system (see section 2.2.2) and This indicates the input and output voltage of others depending on the type of installation: the inverter. In this case, it is important to According to the type of installation there are know the maximum DC input voltage stand-alone inverters are grid-connected admissible, since this data will determine the inverters. Each one has different parameters. number of modules that may be connected in series to the port of the inverter. The output voltage will be a sine wave of the same Stand Alone Inverter frequency of the grid and a voltage of 230 ACV in single-phased systems and 400 ACV in Type of Output Wave: tri-phased systems. The form of output wave of a stand-alone inverter may be: squared, modified sine or Physical characteristics: pure sine. Depending on the type of receiver It is advisable to know the dimensions and connected, you can use one or the other. In weight of the inverter in order to carefuly any case, today we can find pure sine wave plan out its positioning and needs for inverters (which have the best features) and transport and assembly ahead of time. You almost at the same price than others in its should also take into consideration that high class, which is why they come highly power inverters weigh a considerable recommended. amount.
Strain-Voltage: Input voltage is usually 12, 24 o 48 DCV, Insulation / Protection: which will be determined by the voltage of These types of inverters should incorporate a the installation, while the output voltage will series of protections against: be 230ACV. • Electric grid power failure. Power: • Grid voltage out of range. This value indicates the power of the • Grid frequency above strain limits. receivers that we are able to connect to the • Overheating of the inverter. inverter. • Low voltage of photovoltaic generator. • Insufficient intensity of photovoltaic Physical Characteristics: generator. It is a good idea to know the dimensions and weight of the inverter in order to size up the Besides, the most modern inverters come cabinet where it will be installed. with the monitoring function of the point of maximum (peak) power supply (MPPS) incorporated, so they adapt to the levels of Grid-connected inverters voltage and intensity of the PV generator to These devices should be connected to the obtain the maximum power supply possible public grid sending a signal to the network for any level of radiatioin. that is identical in voltage, frequency and
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Assembly: installation should never be modified or When assembling inverters, you should take altered, always respecting the indications and into account that on many occasions these recommendations provided by the devices are installed exposed to the manufacturer (i.e. regarding the necessary elements, so they should have the ventilation of the inverter). 17 corresponding IP. Connection Location This is a simple operation since the manufacturer supplies all of the relevant The inverter should be positioned in a instructions to complete the connection sheltered place, enclosed space inside, away operation without any problem. from the outside elements. In any case, they can always be placed inside a watertight box An inverter usually has two entry terminals to for outdoor use. connect the battery, the current / voltage regulator or the PV park (according to the Besides in stand alone installation should be type of inverter), and two or three alternate places as close as possible to the storage current exit terminals (phase, neutral and batteries, especially since this section suffers ground) for the closed circuit in alternating the most considerable loss of voltage. In any current or external grid (according to the type case, you should always maintain the of inverter). minimum separation prescribed in safety regulations so they are not affected by the With low power inverters, the type of fumes of the storage batteries. available terminals is quite dispersing (type of outlet, for example.) Nevertheless, inverters
of medium to high power are normally FIGURE 86.FIGURE 91. SOLAR INVERTER. (Source: Saecsa energia solar, 2011) equipped with screwed terminals. The instructions of the inverter clearly indicate each terminal with easy to understand symbols. The connection terminals of the inverter are not normally accesible, but rather duly protected since they are out of personal safety range, at entry as well as exit position. (ASIF, 2002)
4.4.3. Storage Battery System
The most important features when selecting Placement a battery are:
Normally all necessary elements to position • Applied technology the inverter on a vertical surface are included • Type. (screws, pliers, etc.). • Capacity. • The inverter usually comes with the Physical characteristics. • appropriate holes and anchors. The Assembly. PVTRIN Training course- Solar installers handbook 108
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Applied technology: Capacity: The batteries employed in photovoltaic solar The capacity of the storage battery is defined energy installations are considered by the energy needs of the installation and stationary, and within this category you can you will have already calculated these during use three different types of technology: lead- the design phase of the project. When we can acid, gel or nickel-cadmium. not find batteries of the exact required capacity, you must select a battery that is in Lead acid batteries are the ones that are excess of the required storage capacity. As most commonly used for their value for we mentioned in the previous section, for money, although they have the disadvantage large storage capacity, you should always of requiring maintenance to avoid electrolyte select the two-volt storage batteries. evaporation, provoking the deterioration of the battery. You should also pay close attention to the C rate of the battery chosen, that is C10, C20, Gel batteries have similar characteristics to C100, etc. As you know, this parameter the lead acid ones, but due to the type of indicates the discharge rate for the particular electrolyte employed, they do not require capacity required. This parameter will also maintenance. For this reason, their use is allow you to compare batteries. becoming more and more popular. For photovoltaic solar energy installations, Nickel-cadmium batteries present the best the use of C20 or C100 batteries is characteristics and performance, lacking any recommended; give the most accurate times type of maintenance. The only disadvantage of discharge to the proper functioning of the is that they are much more expensive than battery. (Tknika, 2004) the previous ones mentioned, so their use is restricted to highly vulnerable services where full-service is key (telephone installations, security systems, etc.) (Tknika, 2004) Physical Characteristics The most important physical characteristics
to keep in mind are: the dimensions and the Type weight. There are two types of batteries: mono block Weight is an important measure because you or 2-volt cell batteries. will need the necessary means of transportation and assembly. Remember that Mono block batteries have 12-volt strain large storage capacity battery cells can weigh voltages and are quite compact. They are considerably. used when the required storage capacity is not very high.
When the storage capacity is rather large Assembly: (more than 1000 Ah), two-volt cell batteries Aside from the appropriate batteries, you should be used in series or parallel to also need to determine the necessary accomodate the necessary storage. There are accessories to install them. Batteries are a number of different storage batteries on often mounted over a supporting isolative the market with different storage capacity. work surface in case of electrolyte ground (Tknika, 2004) spillage and in case the batteries are exposed to ground humidity.
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On the other hand, you must also place ventilated (by artificial or natural means) terminals to isolate contact and avoid because during the charging phase, the gases potential corrosion and also place discharge emitted are extremely dangerous. Besides, hoses in the appropriate section to connect the room should also be free of any potential the batteries adequately. These discharge elements that might cause flames or sparks. hoses are usually sold together with the Depending on the number of storage batteries. In any case, you can do it yourself, batteries necessary, the installation of a shed using the appropriate section. specifically for this purpose may be required, The transfer of the batteries to the location complete with a series of worksurfaces that of assembly should be carried out, allow for proper stability. This also allows you transporting first the empty batteries and to isolate any possible humidity, corrosion or then proceeding to fill them up in the actual acid which they may absorb in case of place of assembly. .When assembling, electrolyte spillage. connecting and handling the batteries, you must use the proper elements of individual protection (EIP) necessary, especially because Placement of the presence of toxic and corrosive The following general guidelines should be substances. strictly followed: When connecting a number of batteries in - Batteries should be emptied before any parallel to increase storage capacity, a type of transport. maximum number of two branches in parallel - When filling batteries with electrolytes, the will be placed in a cross-section. proper safety protection should be implemented, such as masks, gloves, appropriate attire, etc. especially since the The necessary accumulation of electricity electrolytes contain toxic and corrosive produced by panels - if they are not grid- acid. connected, can be elevated, requiring an - The worksurface must be completely level. inordinate number of storage batteries. This means the process of mounting panels may - Insure that the availability of storage be laborious and last more than just one batteries is equal to the specifications extra workday. included in the original design. The three main aspects involved in mounting - When handling storage batteries, proper the storage batteries are their location, mechanical means, suitable in weight, must positioning and connection. be used because the batteries themselves may surpass 100 kg. in weight. - Terminals should never serve for anchoring Location purchases. The batteries should always be located in an - In case an inordinate number of batteries enclosed area, protected from the elements are required, they should be grouped in and not exposed to any direct radiation from batches, leaving enough space between the sun. them to allow for proper maintenance and handling. When the storage batteries used are not sealed, of the liquid electrolyte order, the storage battery room must be properly PVTRIN Training course- Solar installers handbook 110
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FIGURE 87.FIGURE 92. because the manufacturer provides the DIFFERENT AVAILABILITY OPTIONS. (Source: Tknika, 2004) practical solution to connection. (Tknika, 2004)
Parallel Connections To connect several (at least two) in parallel, you should use cross parallel mode. This type of connection facilitates homogeneous discharge for both. If one of these suffers a short circuit, the other(s) will completely discharge in the event of a short circuit, provoking a possible irreversible deterioration in each and every one of them.
FIGURE 88.FIGURE 93. PARALLEL AND CROSSED PARALLEL CONNECTIONS. (Source:Tknika)
Connections
It is indispensable for each connection to dispose of the same exact electrical features.
That is why the same manufacturer and model must be selected. With the exception Serial Connections of substituting a defective battery, new A PV installation that should function at 24 batteries should never be mixed with other volts, needs 2 storage batteries connected in older batteries. series, or joins 12 two-volt cells, in series.
A PV installation that should operate at 48 There are two major groups of batteries: volts, needs 4 storage batteries connected in series, or joins 24 2-volt cells in series. 1. Those that are equipped with terminals (Tknika, 2004) compatible with standard connections; much more flexible connections, as opposed to rigid ones.
2. Those that incorporate their own
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FIGURE 89.FIGURE 94. Serial and Parallel Connections 48 V. 100 Ah. SERIES CONNECTION. 4 BATTERIES. (Source: Tknika, 2004) In this case the desired voltage is obtained by associating several storage batteries in series. This structure forms a branch storage battery system. The desired capacity will be obtained by associating a specific number of branch connectors composed of storage batteries in series, in parallel. We should always make crossed-connections. A PV installation that should function at 24 volts, needs 2 storage batteries connected in series, or joins 12 two-volt cells, in series. A PV installatioin that should operate at 48 volts, needs 4 storage batteries connected in series, or joins 24 2-volt cells in series.
FIGURE 91.FIGURE 96. 4V. 200Ah. MIXED CONNECTION. 2 GROUPS OF 2 SERIAL BATTERIES PARALLEL CONNECTED. (Source: Tknika)
FIGURE 90.FIGURE 95. 24 V. 100 Ah. SERIAL CONNECTION. 2 BATTERIES. (Source:Tknika)
Serial connection with 2 volt cells Since the storage battery serial connection is less problematic than the connection in parallel, you should use 2 volt cells when significant capacity is needed. These should cover the total capacity needed, connected in series, until the desired voltage is obtained.
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• Maximum Short Circuit Intensity: The maximum current supported in case of For example: In a PV installation which short circuit. functions at 12 volts and requires a capacity of 2,000 amperes per hour, we need to connect 6 two - volt cells in series with an Physical Characteristics individual capacity of 2,000 Ah, each one. The most important physical characteristics are: dimensions, weight, and index of insulation 4.4.4. Current / Voltage Regulator Dimensions and weight should be taken into The most important features of a regulator account when measuring the dimensions of are: the cabinet where the regulator will be • Type of Regulation. installed. • Electrical features. The insulation index will indicate if we can • Physical characteristics. place the regulator exposed to the elements • Assembly or not. Generally speaking, regulators are installed in a cabinet that will be as close as possible to the batteries to avoid sudden Type of Regulation drops in voltage, but in such way that it is not Regulators may be connected in series or affected by the vapors of the batteries. parallel, function in two or three stage and have maximum power detection or not. Today, thanks to new advances in electronic Assembly systems, we can find a number of regulators Regulator assembly does not require any with a great number of features at special attention, but as with any piece of competitive prices. , electronic equipment, you should take the Regulators in parallel are recommended for necessary precautions. In many cases, it is low-consumption installations, while advisable to use the necessary protection regulators in parallel may be used in low or against electric overload. Furthermore, you high consumption installations due to the should pay special attention while grounding type of regulation employed. or earthing the equipment and carry out the assembly in the absence of any voltage or tension. Electrical Features When connecting the regulator, follow this The electrical features to take into order: consideration are the following: Connection Battery - Regulator. • Strain-voltage: usually 12, 24 or 48V. a) Connection PV Field – Regulator. There are also bi-voltage models. b) Charge connection. • Maximimum intensity: The maximum current to be regulated. The current / voltage regulator is an • Consumption: The actual consumption indispensable component of stand-alone PV of the regulator itself. systems with energy accumulation (except in cases of minimal power). (ASIF, 2002)
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Location Positioning The suitable placement of the installation The manufacturer has already taken into must meet the following requirements: consideration the matter of positioning. Fastening takes place directly over a vertical
face. The most common method of anchoring Maximum atmospheric temperature must be consists in fixing the structure with a series of less than 45ºC and in a well-ventilated area; screws and hooks. The current / voltage without any leakage or similar potential regulator normally comes equipped with the scenarios; and protected from the elements. necessary holes for anchoring. Therefore, The ideal location is close to the storage there is no need for the installer to make any batteries (especially since this is where the physical alterations (holes, etc.) majority of short circuits occur), but free of The issue regarding proper ventilation of the any gas emmissions. apparatus is extremely important.. (ASIF, 2002) FIGURE 92.FIGURE 97. LOCATION OF THE CURRENT / VOLTAGE BATTERY IN A PHOTOVOLTAIC INSTALLATION. (Source: Tknika,2004) Connections The current / voltage regulator is equipped with a terminal strip, located at the bottom which is duly indicated with symbols for each line. You can identify the three different lines for the Panel, Battery and Metre respectively, together with the indicated polarity for each one. Before proceeding to make any connections, it is important to verify the polarity and corect possitioning of each line, because there is always the danger of making an erroneous connection resulting in short FIGURE 93.FIGURE 98. SOLAR REGULATOR. (Source: Solostocks, 2011) circuits.
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FIGURE 94.FIGURE 99. If this order is not strictlyD followed, for certain DETAILS OF PV REGULATOR CONNECTIONS. (Source:Tknika) regulator models, especially those that function in series, all of the equipment may suffer irreparable damage. In order to disconnect the regulator inside an installation in operation, you must follow the inverse procedure. That is: 1. Disconnect the terminals from the loads. 2. Disconnect the terminals from the PV generator field. 3. Disconnect the terminals from the battery, thus eliminating electric feed.
Wire Gauges to Employ The wire gauge is important to avoid possible Connection Procedure for Current / Voltage short circuits that may result in system Regulator malfunction. When connecting the regulator, the following As a guideline, a short circuit above 3% of the sequence must be strictly followed: nominal voltage under conditions of maximum intensity should not be permitted, 1. Connect the storage battery to the except in the wiring from the regulator to the terminals of the regulator, designated batteries, which will be in the order of 1 %. with the battery symbol. This way, the regulator already receives the preferred Wire Gauge = 2*L*maxI/56*C voltage to feed into its circuit. L is the longitude of the wiring used (metres) 2. Connect the PV generator field to the maxI = Maximum Intensity (A). terminals of the regulator labelled module. C = maximum allowable current (V). 3. Connect the load to the terminals of the regulator as indicated, respecting the NOTE: polarity. “Some regulators possess negatively charged components inside the electronic circuit, which disallows their use in installations in which the negatively charged conductor of the installation may be grounded.”
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4.5. Mechanical Components A number of pre-engineered standoff mounts are available commercially. When installed Installation properly, engineers or test laboratories certify these mounts to be capable of 4.5.1. Adapting the Mechanical Design withstanding specified wind loads. If Once the PV system components have been commercial mounts are used, verification is selected, the installer must decide how best necessary. to install all the parts so the system will be safe, perform as advertised, and look pleasing aesthetically. 4.5.2. Structure Support If the chosen design calls for installation on a There are different types of structures in the sloped roof, the mounts need to be fastened market which vary according to type of solidly to the roof trusses or rafters—not to installation: in floors, facades or rooftops. the roof decking. Depending upon the type of These structures should be rust-proof and roof, the mounts need to be attached in a maintenance-free, such as anodized manner that will ensure that the roof will not aluminum or treated steel. leak at the roof penetrations. Other methods may be allowed with engineered systems that Besides, all of the hardware used should be have been certified by an accredited stainless steel and should comply with organization. applicable regulations in force. Manufacturers of commercially available roof In any case, there are a number of solutions mounting systems provide instructions for in the market that adjust to virtually any type attachment to many types of roofs. Handling of installation. and mounting the modules must ensure that The materials employed in the construction the module edges are not chipped or of structures may vary as a function of the impacted. Small chips or nicks in the glass type, the environment they are subject to, result in high stress points where cracks can resistance, etc. begin with the expansion/contraction associated with temperature. Torque values The main materials used are: given for compression-types of PV mounts • aluminum must be followed. • iron PV Module layout is important for aesthetics • stainless steel and to assist in cooling the modules. A • fibreglass landscape (horizontal) layout may have a slight benefit over a portrait (vertical) layout Regarding assembly, the two main aspects to when considering the passive cooling of the take into consideration are: modules. Landscape is when the dimension • parallel to the eaves is longer than the Location • dimension perpendicular to the eaves. In the Positioning landscape layout, air spends less time under the module before escaping and provides more uniform cooling. Modules operate cooler when they are mounted at least 3 inches above the roof.
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FIGURE 95.FIGURE 100. This stage of the installation may require a PHOTOVOLTAIC FIGURE. (Source: TKNIKA) fair amount of civil construction, so all of the materials necessary should be determined during the design phase. The most frequent civil construction and practical solutions to anchorage are the following: Foundation laying with concrete brake shoe and direct fastening using anchorage blocks.
Location The support fulfills a dual purpose: Apart from specific considerations, such as On one hand mechanical, providing and architectural integration, the structure should ensuring a perfect assembly, supporting be placed in an open location, free of shade winds up to 160 km/h, snow, ice, etc. On the during daylight hours, in such way that the other hand a functional purpose, obtaining modules are situated in the appropriate precise orientation and a suitable angle to direction and at the appropriate angle. make the most of optimal solar radiation. When determining the optimal location of If you are planning on applying for subsidies, the structure, keep in mind the visual impact it is imperative that these structures comply and especially the risk of vandalism. When with the specifications regarding the type of positioning the structure, you probably have installation and with the technical conditions to be present at the actual location in order established by the IEDS. (ASIF,2002) to determine the direction, so the installer should be familiar with the use of a compass, aside from the apparent observed path of the 4.5.2.1. Fixed Structures sun. There are four fundamental ways to Positioning determine the location of the panels: There are two main operations involved in • On the ground positioning: assembly and anchorage. • In posts and/or metallic towers • On walls Assembly consists in the joining and the • On the roof mechanical support of the different components of the structure, such as the The choice of position will depend on the mast, the frame, the shape, etc. features and characteristics of the location, Anchorage consists in fastening the structure always keeping in mind easy access for to the surface or fastening element, (floor, eventual repairs and maintenance roof, facade, etc.) with the objective of operations. providing the necessary resistance and stability to the structure in order to support the maximum amount of wind and snow predictable.
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FIGURE 96.FIGURE 101. The panel can revolve around a vertical axis, DIFFERENT POSSIBILITIES (Source: Tknika, 2004) perpendicular to the work plane, which allows it to monitor the azimuth of the sun on a daily basis. The only parameter that varies here is the azimuth or the change of direction from East to West of the PV generator. FIGURE 98.FIGURE 103. MONITORING THE SOLAR AZIMUTH (Source: Tknika, 2004)
4.5.2.2. Mobile Structures The performance of a PV module depends on the impact of direct solar radiation, among other things. The ideal situation would be that the panels were correctly oriented toward the sun, allowing for a normal effect of the radiation. Monitoring from a single axis angled north- south. The panel can revolve around an axis angled There are different types to monitorize the from North to South, following the route of panels: the sun from East to West. Monitoring the altitude of the sun When the angle of elevation coincides with The panel can revolve around a horizontal the latitude of that particular location, this axis placed in an East to West direction, type of monitoring is called polar monitoring. allowing for daily monitoring of the altitude In this scenario, the production obtained is of the sun. The only parameter that varies is equivalent to 96% of that obtained by dual the angle of the PV generator. axis monitoring.
FIGURE 97.FIGURE 102. FIGURE 99.FIGURE 104. MONITORING THE ALTITUDE OF THE SUN (Source: Tknika, MONITORING FROM A SINGLE AXIS ANGLED NORTH-SOUTH. 2004) (Source: Tknika, 2004)
Monitoring the solar azimuth
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Dual axis monitoring 4.5.3. Anchorage Systems The panel revolves around two axises: one changes the elevation, following North to Points of Support South, and the other changes the azimuth, One of the most important aspects to take following the East-West path of the sun. into consideration regarding structures is the points of support because the strength of the
structure depends on them as a whole. In this type of monitoring, when the angle of It is futile to calculate a structure that might the azimuth axis coincides with the latitude of support very strong winds if we do not insure that specific location, you gain the best angle that the structure is properly secured to the of solar impact, so the production of obtained ground, roof, etc. by the PV generator is maximum. In FIGURE 102FIGURE 103, we can see the FIGURE 100.FIGURE 105. DUAL AXIS MONITORING. A) (Source: Tknika, 2004) four different types of bases for ground or roof structures. FIGURE 102.FIGURE 107. POINTS OF SUPPORT (Source: Tknika, 2004)
Also, there is another kind of monitoring that the panel can revolve around both axises: one changes the elevation and the other moves around the axis angled North-South, following the path of the sun. A) Foundations with concrete slabs and perimeter base. FIGURE 101.FIGURE 106. Dual axis monitoring. (Source: Tknika, 2004) B) Foundations with wooden beams of less duration. C) Foundations with concrete blocks D) Metallic foundations firmly anchored to the ground.
Elements of Anchorage In the diagram, you can see two different ways of docking the leg of the structure to the foundation, using screws.
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There is another procedure that consists in introducing pieces of metal into the base of the concrete, in such way that, when you lay the concrete, they will be solidly joined together.
FIGURE 103.FIGURE 108. ELEMENTS OF ANCHORAGE (Source: Tknika, 2004)
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4.6. Grid-connected PV Systems The fact that we have a connection to an “Those systems in which the electric energy electric power supply does not impede us generated by the photovoltaic field flows from making the most of PV solar energy. The directly into an external power supply” energy generated can be injected directly into the electricity grid, using a special convertor, so we can avoid the expensive
costs of batteries and regulators.
FIGURE 104.FIGURE 109. GRID-CONNECTED INSTALLATION (Source: Tknika, 2004)
FIGURE 105.FIGURE 110. GRID-CONNECTED INSTALLATION UNIFILAR DIAGRAM (Source: Tknika, 2004)
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4.6.1. Topology of the installations Point of connection to the Power Grid In PV installations that are connected to the grid, we can distinguish between two For installations connected to single-phase or different parts: DC (Direct Current) and AC triphased grids of 230V/400V, the connection (Alternating Current). will be established upstream of the electric meter that belongs to said grid. The first part deals with PV Generators, their circuit breakers and the convertor. The second category deals with the Convertor, its circuit breakers and electric meters.
FIGURE 106.FIGURE 111. A BLOCK DIVISION OF GRID CONNECTED INSTALLATION (Source: Tknika, 2004)
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4.7. Stand-alone PV System Stand-alone installations may be constructed for direct or alternating current. In stand-alone installations, the energy generated is stored and the owner of the facility consumes the power generated The type of installation to construct will (individual consumption). Other installations depend on the number and electrical connected to the electric grid are directly features of the elements of consumption. injected into an external power supply - void When constructing low-power installations, of any storage – and is used by all the you can use a direct current of 12, 24 or 48 consumers that belong to this network. volts. High-power installations require an alternating current of 230 volts to avoid large No matter what the case, in both instances wire sections. the owner of the installation may be an individual or a corporation. Certain recipient elements are manufactured in direct or alternating current, so the In general, these types of installations are installation will be carried out according to used in remote areas where it is difficult or the type of electric feed required. even impossible to connect to the electric grid for economic, technical or accessibility issues.
FIGURE 107.FIGURE 112. STAND-ALONE PV SYSTEM ( Source: TKNIKA)
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When determining the size of a photovoltaic 4.8. Completing the PV installation system, we need to keep in mind its application. We cannot use the same design After installing the PV panel, the installer criteria for a lighting system, for a weekend should perform the following procedures: getaway home, than for a radio link or road • Start up and running of the system signalling apparatus. • Testing the security of the system and all In the first case, economic criteria concerning safety measures operational safety are top priority, while in • Delyver installation the second case; we should oversize the entire system and choose materials according Inspection and testing to road safety and quality standards in order Inspection and testing of the completed to keep the probability of installation defects system to the Wiring Regulations must be to a minimum. carried out and documented. Determining the size of an installation should Inspection and testing documentation begin by informing the user of the features, typically comprises 3 forms – an installation characteristics and limitations of the certificate, which includes a schedule of items installation in a clear and concise manner. inspected and a schedule of test results. The inspection and testing of D.C. circuits, Given the fact that a photovoltaic installation particularly testing PV array circuits requires has no type of technical limitations regarding special considerations. Appendix C covers the the power it is able to generate, the project inspection and testing of PV array circuits and manager should take down all of the documentation to be provided. necessary information from the user concerning: Array commissioning tests • Location • Purpose PV array/string performance tests are • Amount of usage recommended to verify performance as a check for faulty modules.. This may require a • Technical features of recipient elements means of measuring solar radiation for larger installations if radiation levels are changing • Number and characteristics of future during testing. Potential users • Credit history Simultaneous monitoring of the solar radiation can present practical difficulties unless the system has a radiation sensor
installed and its cable is accessible at the place where testing is carried out. If radiation conditions are reasonably constant (ie no sudden obscuring of direct sunlight by clouds), comparing one open-circuit string voltage with another will identify faulty strings.
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TABLE 23. SCHEDULE OF TEST RESULTS. (Source: DTI, 2006)
Field insulation test procedure - Module/laminate terminals with any part of your body when performing the insulation
test. Safety: - Whenever the Insulation test device is - Read and make sure you understand this energised there is voltage on the testing procedure before you start any work. area. The equipment is to have to have - Insulation testing is an electric shock hazard automatic auto-discharge capability. use caution when performing the testing. - Do not perform the test before you have Note regardint test method received practical training. Two test methods are possible: - Limit the access to the working area. a) Test between Array Negative and Earth - Do not touch and take measures to prevent followed by a test between Array Positive and any other persons to touch any metallic Earth surface with any part of your body when performing the insulation test. b) Test between Earth and short-circuited - Do not touch and take measures to prevent Array Positive & Negative any other persons to touch the back of the Where the structure/frame is bonded to module/laminate or the insulation test. earth, the earth connection may be to any PVTRIN Training course- Solar installers handbook 125
suitable earth connection or to the array positive and Array negative cables - short- frame (where the array frame is utilised, circuit the cables with an appropriate short- ensure a good contact and that there is circuit junction box. continuity over the whole metallic frame). 4) Connect one lead from the Insulation For systems where the array frame is not Resistance test device to the array cable(s) as bonded to earth (eg where there is a class II per the NOTE above. installation) a commissioning engineer may 5) Connect the other lead from the Insulation choose to do two tests: i) between Array Resistance device to Earth as per NOTE above cables and Earth and an additional test ii) between Array cables and Frame. 6) Secure all the test leads (eg with cable ties). For Arrays that have no accessible conductive parts (eg PV roof tiles) the test should be 7) Follow Insulation Resistance Test Device between Array cables and Building Earth. instructions to ensure the test voltage is according to TABLE 24 and readings in M
Ohms. Test Zone Preparation: 8) Follow Insulation Resistance Test Device 1) Limit access to non-authorized personnel. instructions to perform the test. 2) isolate the PV array from the inverter 9) Ensure system is de-energised before (typically at the array switch disconnector) removing test cables or touching any conductive parts. 3) Disconnect any piece of equipment that could have impact on the insulation measurement TABLE 24. TEST METHOD TABLE (Source: DTI, 2006) (I.e. overvoltage protection) in the junction or combiner boxes. Equipment Required: • Insulation resistance test device • Insulation gloves • Goggles. • Safety boots. • Short-circuit box (if required)
Procedure 1) The test should be repeated for each Array After running the newly installed system for a as minimum. It is also possible to test minimum of 240 hours without incident, the individual strings if required. provisional act of certification may be signed. 2) Wear the safety shoes, gloves and goggles.
3) Where the test is to be undertaken between Earth and short-circuited Array
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Testing and Delivery 4.8.1. Documentation to the customer After preliminary testing, before delivering An authentic project should always include the finished product, the installer must: the applicable legislation regarding the • Clean up any excess material installation, taking into consideration all • Thoroughly clean the zone occupied technical as well as environmental aspects. In by the panels this sense, there is a great distinction between photovoltaic systems and those The installer must also provide the user with which are connected to the power grid, an operations manual. especially since the latter involves a much more extensive legal procedure.
TABLE 25. COMMISSIONING TEST SHEET (Source: DTI, 2006) When embarking on a project after recieving the appropriate information from the customer and their needs, you need to adhere to the following action plan which includes: feasability study, annual report, blueprints, list of conditions, budget, safety plan, etc. In this way, and with the pertinent information available, the installer will be able to perform the installation in the alloted time for the project and meet the applicable quality standards.
4.8.1.1. Feasability Study Before undertaking the project itself, the designer, taking into consideration the needs of the customer and type of installation, must: Evaluate the energy needs and interests of the user in order to determine the most appropriate type of installation and its features. Determine the potential level of solar power generation of the region where the installation is to take place in order to quantify the feasability of the application of solar power. To this end, different means should be used: charts or available statistics, on-site measurements, use of computer systems, etc.
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The finished product will be an economic and technical study of the proposed installation for the customer's consideration.
The installer will also provide the user with a copy of the project, which may include the following sections as a guideline: • Feasability study • Report • Technical Drawings • List of Conditions • Budget • Safety Plan
Furthermore, the installer must also provide the user with an operations manual for the installation and perform the following tests: a) Start up and running of the system b) Testing the security of the system and all safety measures
After running the newly installed system for a minimum of 240 hours without incident, the provisional act of certification may be signed. Finally, the installer must: - Remove all excess residual materials. - Thoroughly clean the occupied space.
4.9. Installation checklist
Once installation has been completed, we need to check how the system runs. The following chart includes the items and parameters you will need to verify, as an example. In any case, this checklist may vary depending on the type and features of the installation.
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TABLE 26. PV COMMISSIONING TEST SHEET. Source: BRE et al, 2006)
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4.10. Exercises aesthetically suitable. c) Know if they meet the mandatory 4.10.1. Questions standards.
• What property of PV modules makes them hazardous to install when they are The structures used in a photovoltaic exposed to daylight? installation must be:
• What combination of hazards needs to be a) Tailormade for each individual assessed when completing a risk installation. assessment and method statement for b) There are no regulations regarding this the installation of PV systems? point. • Why can’t fuses be used to protect PV c) Made of rustproof material and must module wiring? not require maintenance.
• The behaviour of dc electricity is different
from that of ac electricity what hazards In systems of high volume acumulation does this present? they use: • Prepare a generic method statement and risk assessment for the installation of a a) Lead gel batteries. . PV system on a pitched roof b) Two volt glasses. c) Monobloc batteries.
The safety plan will be carried out by: The safeguards that should be used for a
grid-connected photovoltaic installation: a) The user of the installation.
b) The designer of the project. a) Are up to the criteria of the designer. c) The installer. b)Should fulfill the pertinent legal
requirements. The project report: c)There are no pertinent legal
regulations. a) Explains the purpose of the project and
describes the procedure to follow for
completion. The objective of a grid-connected b) Contains the obligations of the installer photovoltaic installation is: when executing the project.
c)Explains the potential risks and a) Self-sufficiency. preventive measures to be taken. b) Inject the energy generated into the
grid for free. The features of a photovoltaic module c) Inject the energy generated into the are important because they allow you grid for sale. to:
a) Know the space the photovoltaic fields will occupy and the need for A grid-connected installation consists of transportation or mounting. three components: b) Know if the chosen location is PVTRIN Training course- Solar installers handbook 130
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a) Generator, storage battery and power a) The modules serve an energy and supply. architectural purpose and also substitute certain elements of the building construction b) Generator, converter and power supply. b) The modules serve an aesthetic and c) Generator, converter and storage battery. architectural purpose and also substitute certain elements of the building construction The point of connection of the installation is: c) The modules serve an energy and a)Downstream of the electric metre. architectural purpose, but do not substitute any of the elements of the building b)Upstream of the electric metre. construction. c) Wherever the client desires. The different forms of building integration In a stand-alone installation, consumption are: takes place: a) Enclosures, shading, layering and general. a) Exclusively in DC. b) Enclosures, shading, covering, layering and b) Exclusively in AC. general. c) In AC, DC or both simultaneously. c) Enclosures, shading, covering and layering.
To avoid the DC conductor section from Total building integration occurs when: being too large, we should: a) When the integration of the sensors is a) Lower the strain-voltage. completed after the conception of the building. b) Increase the strain-voltage. b) When the integration of the sensors is c) Insure that the distance between the completed from the moment the building is generator and consumption is as long as conceived. possible. c) When the integration of the sensors is completed at any phase of the project. The amount of a drop in voltage admissible in power lines: El valor de la caída de tensión admisible en las líneas: Optimal building integration is achieved at which stage of development: a) Will be defined by the applicable regulation for these types of installations. a) Building in project development. b) Depends exclusively on the criteria of the b) Building under construction. designer. c) Building construction complete. c) Will be determined by mutual agreement between customer and designer.
Building integration occurs when: The objective of building integration systems is: PVTRIN Training course- Solar installers handbook 131
a) To improve the aesthetical appearance of the installation. b) To fulfill the applicable regulations in effect. c) To get the modules to serve an energy and architectural purpose substituting the constructive elements of the building.
The installer must provide the user with an operations manual for the installation.
True.
False.
Before handing over the provisional ownership of the installation: a) It is necessary to leave the installation running for a minimum of 240 hours. b) Here is no need to leave the installation running. c) The customer will give their final approval.
It is necessary to run periodic checks on the operational parameters of the installation. True. False.
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5. CASE STUDIES – BEST 5.1. PV installation in Aurinkolahti PRACTICES Comprehensive School
City (Country): Helsinki (Finland)
Type of application: roof mounted For the Case Studies section of this Handbook we chose small-scale PV systems Year: 2009 implemented using different technologies, on different type of buildings throughout Europe. 5.1.1. Summary The selection criteria for these case studies The City of Helsinki is committed to many are: technical and aesthetical aspects and the energy efficiency agreements as well as novelty of the systems, in order to showcase reducing CO2 emissions. With those systems that use most advanced technology agreements the City of Helsinki is also and approach. committed to use more and more renewable energies. Solar power station of Aurinkolahti is one of the pilot projects The best practices presented in this section are likely to be the kind of PV systems on when testing renewable energies. The which future installers will work on and the target annual energy saving at the school information included will help them avoid of Aurinkolahti is 6,5 % every year when making common mistakes while developing a compared to purchased electrical energy correct approach to implementing PV consumption. solutions.
5.1.2. Description of the solution
Background description - Description of the site/building type:
School building
- Partners and stakeholders involved: the City of Helsinki, Public Works Department, PWD Construction Management - Duration of the pilot project: about six months - Duration of the installation works: about two weeks
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5.1.3. Results/achievements - Energy production: 14 691 kWh/first year of action (L3 phase inverter failure from June 2010 to August 2010 influenced 5000 kWh loss of energy production) - CO2 emissions reduction: 3482 kg CO2 (emission factor used: 237 g CO2/kWh) - Other benefits: educational purpose FIGURE 108.FIGURE 113. when teaching natural sciences AURINKOLAHTI SCHOOL. (Source: City of Helsinki)
Technical description 5.1.4. Replication - Total installed power: 20,4 kWp - Advice on how to replicate the solution and - Area needed per kW: 7,35 m2/kW on steps to follow/barriers to look-out for. The solution can be copied elsewhere. - PV technology used: Crystalline silicon technology Every power station carried out with solar panels must be dimensioned case by case - Type of Inverter: SMC6000TL (6300 W, before implementation. This means both 600 V, 26 A) constructional and electrical dimensioning - Maintenance, warranties and lifetime of very carefully. solution: the system is nearly maintenance free; duration of guarantee is 25 years, expected lifetime about 30 years 5.1.5. Contact details Economic aspects - Contact person e-mail: - Total cost of solution and cost of PV: [email protected] 140 783 €, 6,90 €/W - Funding for implementation and sources: 35% of total costs funded by Ministry of
Employment and the Economy
- Feed-in tariffs, subsidies, local/regional or national grants: There is no Feed-in tariff in Finland for decentralized electricity production
- Internal rate of return (IRR) for the solution: Payback time (without interest) 25 to 50 years depending on the electricity market prices
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5.2. PV plant on the Kungsmad School
City (Country): Växjö, Sweden Latitude/Longitude: 56° 53' N / 14° 49' E Type of application: roof mounted
Year: 2008 FIGURE 110.FIGURE 115. PVSYSTEM ON SCHOOL. (Source: Kari Ahlqvist)
5.2.1. Summary
The City of Växjö has a very ambitious 5.2.2. Description of the solution climate and energy plan, to become free from fossil fuels by 2030. So far the main Background description focus has been biomass, but in recent - Description of the site/building type: The years, solar energy has become more PV plant is mounted on the roof of a interesting. The PV plant on the secondary school. Kungsmad School was the second PV - Partners and stakeholders involved: The plant to be built in Växjö and it is still the municipal real estate company Vöfab, and the largest in the area. In fact, it is one of the installation company Glacell AB biggest of its kind in Sweden. It consists of - Duration of the installation works: about 1 780 panels over an area of 1 021 m2. The month plant generates about 130 000 kWh of electricity every year, which is estimated to represent 1/6 of the school’s annual Technical description electricity use. The current energy - Total installed power: 137 kWp production as well as CO2 savings are 2 shown to the public at a display attached - Area needed per kW: 7,45 m /kW to the wall. - PV technology used: Polycrystalline silicon FIGURE 109.FIGURE 114. DISPLAY OF PV SYSTEM. (Source: Kari Ahlqvist) - Type of Inverter: IG 500HV - Maintenance, warranties and lifetime of solution: There is a warranty time of 25 years. We have no calculation of expected lifetime. So far, no specific maintenance has been performed. There may be a need for cleaning later on.
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Economic aspects - Total cost of solution and cost of PV: 500 000 € (3,65 €/Wp) - Funding for implementation and sources: Governmental subsidy 70%, Vöfab 30% - Feed-in tariffs, subsidies, local/regional or national grants: Governmental subsidy of 70 %. - Internal rate of return (IRR) for the solution:
No internal rate of return has been set. FIGURE 111.FIGURE 116. PV SYSTEM ON ROOF. (Source: Kari Ahlqvist)
5.2.3. Results/achievements 5.2.5. Contact details - Energy production: Approximately - Online information on the solution 130 000 kWh per year www.vofab.se - CO2 emissions reduction: 78 000 kg CO2 - Contact person e-mail
[email protected] 5.2.4. Replication - Advice on how to replicate the solution and on steps to follow/barriers to look-out for.
This PV plant as well as the first one in
Växjö, have paved the way for a more frequent use and higher interest in PV systems in Växjö. It is quite a simple solution. This installation shows that it is possible to produce electricity from the sun even in Sweden.
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5.3. Solar power plant BERDEN
City (Country): Bogojina, Slovenia Latitude/Longitude: 46°/16° Type of application: BIPV Year: 2011
5.3.1. Summary
Solar PV modules are integrated in the FIGURE 112.FIGURE 117. roof of a new building. Integrated solution BERDEN SOLAR PLANT. (Source: www.plan-net.si) was made in terms of saving additional costs for roof covering. Roof is covered - Type of Inverter: Riello HP 1000065, 10 with 216 PV modules Upsolar UP-M230P. kW For 49,68 kW power plant we used five 10kW Riello inverters. Power plant will - Maintenance, warranties and lifetime of yearly bring 30 t Co2 savings. solution: Project lifetime is estimated to 30 years, warranties were made for PV modules (10 years), inverters (5 years), 5.3.2. Description of the solution and general warranty (2 years.)
Background description - Description of the site/building type: Economic aspects Building is located in NE Slovenia and is used for business purposes. - Total cost of solution and cost of PV: - Partners and stakeholders involved: Investor is a home employed farmer. 3,14 €/Wp; cost of PV: 1,97 €/Wp - Duration of the installation works: - Funding for implementation and sources: Work was carried out in a period of one Equity capital month. - Feed-in tariffs, subsidies, local/regional or national grants: Technical description 0,444 €/kWh - Total installed power: 49,68 kWp - Internal rate of return (IRR) for the - Area needed per kW: 7,1 m2/kW solution: - PV technology used: Crystalline silicon 10%.
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5.3.3. Results/achievements - Energy production: 49 MWh per year
- CO2 emissions reduction: 30 000 kg CO2, (based on a global average 0.6 kg of CO2 per KWh.)
5.3.4. Replication - Advice on how to replicate the solution and on steps to follow/barriers to look-out for. The solution can be replicated at every similar building with similar orientation. A well prepared project is the basis for good execution.
5.3.5. Contact details
- Online information on the solution www.plan-net-solar.si
- Contact person e-mail
Femc Marko ( [email protected] )
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5.4. PV system on school in Šmartno ob Dreti
City (Country): Šmartno ob Dreti, Slovenia Latitude/Longitude: 46.28406/ 14.88854 Type of application: BAPV Year: 2010
FIGURE 113.FIGURE 118. 5.4.1. Summary PV SYSTEM ON ROOF. (Source: BISOL Group d.o.o) Solar power plant MFE OŠ Šmartno ob Dreti in Slovenia is a roof top PV system of the PV modules is 13° southwest. In the installed on a primary school. The immediate vicinity of the PV system is a investor, BISOL, used 99 BISOL 245 W block of flats, which does not cast photovoltaic modules. The installed shadows on the PV system. power is 24,25 kW. Production until today
(October 27, 2011) is of 24 MWh, which exceeds the expected energy yield by - Partners and stakeholders involved 8, 5 %. Investor: BISOL Group d.o.o.
- Duration of the works: 5.4.2. Description of the solution The Easement Agreement was signed on Background description September 1, 2010; the solar power plant - Description of the site/building type: was connected to the grid on December The primary school in Šmartno ob Dreti is 14, 2010. Works on the roof started on older facility with brick roof. The roof is in November 10 2010, and the whole PV good condition; therefore the system (together with laying the cable replacement of the roofing was not conduits) was installed 8 days later. necessary. 99 BISOL multi-crystalline Another 3 weeks passed before the silicon photovoltaic modules, each with official documentation from the utility power 245 W, were installed on 160 company was issued. square meters. As BISOL modules have strictly positive power output tolerances the total installed and measured capacity Technical description of the PV system is 24, 25 kW. Orientation - Total installed power (kW): 24, 25 kW - Area needed per kW: Approx. 7 m²
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- PV technology used: Crystalline silicon 5.4.3. Results/achievements technology - Energy production: annual energy - Type of Invertor (power and rating): production until today (October 27, 2011) one SMA 1500 TL and two SMA SB 400 TL is 24 MWh, expected annual energy - Maintenance, warranties and lifetime of production is 22, 1 MWh, surplus 8, 5% solution: - CO2 emissions savings: 14400 kg Maintenance and monitoring contract - Jobs created: Many people worked on the with BISOL Group d.o.o.; Warranties: 10- project: salesmen, project managers, and year product warranty; 12-year warranty purchasing and warehouse division, 5 on 90 % power output, 25-year warranty installers and many others. on 80 % power output, 1-year warranty on flawless working of the PV system - Other benefits: For educational purposes (until December 14, 2011). Expected BISOL placed an LCD player in the school, lifetime: more than 40 years which enables pupils to monitor solar power plant operation. This contributes to the learning process and increases the Economic aspects environmental awareness among the children. - Total cost of solution: 70.325,00 EUR - Funding for implementation and sources: 5.4.4. Replication 80 % bank credit, 20 % own resources - Advice on how to replicate the solution and on steps to follow/barriers to look-out for. - Feed-in tariffs, subsidies, local/regional or national grants: As with all PV power plants a detailed review of the site is needed, the roof has to be in a BISOL rented the school’s roof area for 25 good shape, special attention should be paid years. All produced electricity is sold to to orientation of the building, shading etc. the Centre for Renewable Energy Sources Support at guaranteed purchase price. Feed-in tariff for year 2010 (for micro 5.4.5. Contact details solar power plants on buildings) was 386, 38 EUR/MWh. This is a guaranteed - Online information on the solution: www.bisol.com purchase price for 15 years. - Contact person e-mail: [email protected] - Internal rate of return (IRR) for the solution: • after 7 years 5,4% • after 10 years 10,7% • after 15 years 13,7%
• after 20 years 15,3%
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5.5. Athens Metro Mall
City (Country): Athens, Greece Latitude/Longitude: 37.941363 /23.739974 Type of application: BIPV Year: 2010
FIGURE 114.FIGURE 119. 5.5.1. Summary ATHENS METRO MALL. Designed on the axis of saving resources and being environmental friendly, Athens - Area needed per Kw: 7,72 m2 Metro Mall combines characteristics which make it bioclimatic building with - PV technology used: Crystalline silicon very low energy consumptions. Solar - Type of modules: SCH660P from SOLAR panels cover 400sqm of the south side of CELLS HELLAS SA the building achieving reduction of the energy consumption up to 5%. - Type of Inverter: Sunergy ELV 230/5000W Maintenance services are - Maintenance: offered by the contractor ACE POWER 5.5.2. Description of the solution ELECTRONICS Background description - Warranties: 5 years for Inverter and PV - Description of the site / building type: panels The BIPV consists of two facades and the - Lifetime of solution: approximately 25 south side of the Trade center “Athens years. Metro Mall”. - Partners and stakeholders involved: Economic aspects The whole project has been financed by - Total cost of solution and cost of PV: TALIMA VENTURE INC which happens to 142.000 €, 2,78 €/Wp be the owner of the trade center.
- Duration of the works: - Feed-in tariffs, subsidies, local/regional or The duration of works was 20 days. national grants: The system injects power in the public greed. The power is paid according to the Technical description feed-in tariff - 0,394€/KWh by the public - Total installed power: 51 kWp power corporation (PPC). In theory the system will produce approximately PVTRIN Training course- Solar installers handbook 142
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39,9MWh/year which means that the total investment will be compensated approximately in 9 years.
5.5.3. Results/achievements - Energy production: 39.900 kWp /year - CO2 emissions savings: 23.940 kg
5.5.4. Replication FIGURE 115.FIGURE 120. ATHENS METRO MALL. - Can the solution presented be replicated in other areas? The system can be easily replicated in other buildings.
5.5.5. Contact details - Online information on the solution: www.schellas.gr , www.acepower.gr
- Contact person e-mail:
Ms. Eirini Komessariou ([email protected]) Mr. Ioannis Aggelos ([email protected])
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5.6. Roof and wall mounted system in Finland
City (Country): Helsinki (Finland) Type of application: roof and wall mounted Year: 2009
FIGURE 116.FIGURE 121. L 5.6.1. Summary ATOKARTANO SCHOOL. (Source: City of Helsinki) The City of Helsinki is committed to many energy efficiency agreements as well as Technical description reducing CO emissions. With those 2 10, 6 kWp agreements the City of Helsinki is also - Total installed power: committed to use more and more - Area needed per kW: 7, 35 m2/kW renewable energies. Solar power station - PV technology used: Crystalline silicon of Latokartano is one of the pilot projects when testing renewable energies. The - Type of Inverter (power and rating): annual target of saved energy at the SMC4600TL (5250 W, 600 V, 26 A) school of Latokartano is of 4 %. - Maintenance, warranties and lifetime of solution: The system is nearly maintenance free; duration of guarantee is 25 years, 5.6.2. Description of the solution expected lifetime about 30 years. Background description
- Description of the site/building type: Economic aspects School building - Total cost of solution and cost of PV: - Partners and stakeholders involved: 87 275 €, 8,23 €/W the City of Helsinki, Public Works - Funding for implementation and sources: Department, PWD Construction 35% of total costs funded by Ministry of Management Employment and the Economy - Duration of the pilot project: - Feed-in tariffs, subsidies, local/regional or new building construction, about two national grants: There is no Feed-in tariff in years Finland for decentralized electricity production - Internal rate of return (IRR) for the solution: Payback time (without interest) 25 to 50 years depending on the electricity market prices PVTRIN Training course- Solar installers handbook 144
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5.6.3. Results/achievements - Energy production: Approximately 9500 kWh/first year of action
- CO2 savings: 2252 kg CO2 (emission factor used: 237 g CO2/kWh) - Other benefits: Educational purpose when teaching natural sciences
5.6.4. Replication - Advice on how to replicate the solution and on steps to follow/barriers to look-out for. The solution can be replicated elsewhere. Every power station carried out with solar panels must be dimensioned case by case before implementation. This means both constructional and electrical dimensioning very carefully.
5.6.5. Contact details - Contact person e-mail: [email protected]
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5.7. Blackpool Centre for Excellence in the Environment
City (Country): Blackpool (United Kingdom) Latitude/Longitude: 53°47'0"N 3°3'27.56"W Type of application: Inclined roof - transparent roof FIGURE 117.FIGURE 122. Year: 2004 BLACKPOOL CENTRE FOR EXCELLENCE IN THE ENVIRONMENT. (Source: Blackpool City Council)
5.7.1. Summary - Partners and stakeholders involved: A derelict seafront solarium in Blackpool The Centre for Excellence in the has been renovated and refurbished to Environment, also known as Solaris, is a act as a Regional Centre of Excellence in sub-regional multi-agency partnership. Environmental Sustainability in the North The project was commissioned by West of England. Sustainable energy is a Blackpool Borough Council and is key element of the refurbished building intended to contribute to tackling the with onsite energy generation from a major regeneration challenge facing photovoltaic (PV) installation, two wind Blackpool. Other partners in the project turbines and a combined heat and power include Lancaster University, Blackpool (CHP) plant. This innovative project and the Fylde College and Blackpool provides a focus and platform for Environmental Action Team delivering and promoting sustainable development across the tourism, - Duration of the pilot project: manufacturing, commercial, education From 2003 to August 2004 and community sectors, both locally and regionally. The PV array supplies up to Technical description 44% of the building’s annual electricity - Total installed power: 18,067 kWp requirements. - Area needed per kW: 9,08 m2/kW
- PV technology used: Multi-Crystalline 5.7.2. Description of the solution silicon technology
Background description - Type of Inverter (power and rating): SMA (4 types -SMR1700, SMR3000, - Description of the site/building type: SMR2500, SMR850) Non-residential buildings - 2 floors Combined nominal inverter power: 14,85kW
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Economic aspects - Total cost of solution and cost of PV: 306 054 €, 16,93 €/W - Funding for implementation and sources: The grant from the Major PV Demonstration Programme funded 65 % of the PV installation (151 000 €) with the remainder coming from the overall project budget.
5.7.3. Results/achievements - Energy production: 12.776MWh - Other benefits: The building was designed to meet best practice guidelines and has attained an excellent rating from the BREEAM environmental assessment. The energy FIGURE 118.FIGURE 123. usage within the building is monitored BLACKPOOL CENTRE FOR EXCELLENCE IN THE ENVIRONMENT. and optimised via real time monitoring. (Source: Halcrow Group ltd)
Solaris was built as a foundation for the education and promotion of sustainable 5.7.4. Replication design and incorporation of renewable - Advice on how to replicate the solution and energy in the area. The building is of on steps to follow/barriers to look-out for. passive design, taking advantage of During the installation of the PV system, natural energy flows to maintain thermal relatively few problems were comfort and negate the need for encountered. Some of the PV modules mechanical heating and cooling. were damaged during shipping but The building fabric comprises of recycled replacement modules were simply and sustainable materials: the building’s ordered to replace them. Close contact concrete blocks contain pulverised fuel was maintained between the installation ash, a by-product from the power partners to ensure a satisfactory design industry; and recycled newspapers are was agreed on, allowing the innovative used as insulation in the external cavity double glazed PV modules to be ordered. wall. The close liaison allowed the effect of design changes, including shading issues, to be catered for in the choice and positioning of the PV units and also enabled a coordinated effort in the
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renovation of the solarium and installation of the new technology. Prior to installation there was some concern over the effect of wind-blown sand and salt build up from the nearby shore, however this problem has not materialised.
5.7.5. Contact details - Online information on the solution: www.solariscentre.org
- Contact person e-mail: [email protected] [email protected]
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EXAMPLE INSTALLATION OF A SMALL SCALE PV ON BUILDING 6
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6. EXAMPLE INSTALLATION OF
A SMALL SCALE PV ON Energy data – presents calculated energy production and other technical parameters of BUILDING the system Summary project report – creates short 6.1. Used software Tool – PV*Sol project report PV*Sol is a computer software used for Variant comparison – compares selected simulation and calculation of PV systems, project with other project both off-grid and on grid. PV*Sol has a toolbar just below Menu bars, similar to the most Windows applications Short description of these icons is as follows: Language selection – used for local language setup MeteoSyn – used for loading/entering a
climate data New project – opens new project Open project – opens existing project 6.2. Description of a building Save project – saves project Selected building is situated in urban environment of City of Zagreb, and it serves as public building (theatre). Building is
connected to the local distribution grid via Technical data – selection of technical existing connection as consumer with parameters and equipment connection power of 96 kW . Climate data – selection of climate data FIGURE 119.FIGURE 124. Orthophoto of building and suroundings Feed-in tariff – selection of appropriate tariff system Shadings – allows assessment of the shadings for location Losses – defines other losses in system
System Check – determinates if system is sized correctly Simulation – runs the simulation Economic efficiency calculation – calculated financial payback of the project Annual energy balance – presents technical calculated production of energy
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Building has three stories, with three terraces 6.4. Determination of climate (flat roofs) on the top of building Southern terrace (hatched in FIGURE 120FIGURE 121) is conditions selected for installation of PV modules. On Productivity of PV system basically depends this terrace is situated a external air on two climate factors: solar irradiation and conditioning device, which will be removed to air temperature. These data can be retrieved the northern terrace. Roof is concrete from local publications on solar energy construction with satisfactory static potential, or from some on line services, such parameters that can campaign the load from as PVGIS. PV modules and supporting structure.
FIGURE 120.FIGURE 125. In selected case, data on solar irradiation on SOUTHERN TERRACE (view from NW) horizontal surface and average air temperature over the months are available in Solar atlas of Croatia, which is based on 30 years measurement data. Under the “Climate data” data for specific location can be selected if this file exists. If not, they can easily be entered under the MeteoSyn button.
FIGURE 121.FIGURE 126. SOLAR IRRADIATION AND AIR TEMPERATURE FOR SELECTED LOCATION
7 25
6 20
5
15 6.3. Selection of the equipment 4 3 10
2
Selection of equipment used for the PV plant Average daily irradiation (kWh/m2) 5 mostly depends on financial factors, not on 1 0 0 January February March April May June July August September October November December technical factors. When selecting PV modules Irradiation on horizntal plane Average air temperature and inverters, care should be taken regarding applied certificates (IEC and local standards). Based on climate and geographical data, Taking into account a profitability of PV PV*Sol will calculate optimal angle, by system, electricity production versus price pressing “Tilt angle Max Irradiation” button, should be considered for several offers. This which is in selected case 28°. In case of flat is usually iterative process. roof, optimal angle is recommended to be used for calculations In case of flat roof, angle For this plant, PV modules with power of of the roof as well as orientation should be 230W from local manufacturer are selected. estimated or measured and entered in the Dimensions of these modules are propriate fields (Orientation and Inclination) 1663x0998[mxm]. Inverters are selected under the Technical DataPV Array . based on various offers, taking into consideration efficiency as well as matching of inverter with PV modules/array. PV modules are selected under the Technical dataPV module selection in PV*Sol, which list all the modules in PV*Sol’s database. PVTRIN Training course- Solar installers handbook 151
6.5. Determination a appropriate determination, “Free standing” installation type should be selected, as well as size of PV system “Determinate Output from Roof area” Physical dimensions of the roof, either flat or Under the Technical data Roof parameters pitched will determinate maximum possible Min Distance between Modules tab it is size (installed power) of the PV system on the necessary to check “Use minimum Distance building. For pitched roof, only dimensions of for Mounting” In next tab (No of modules per the southern (or south-east/south-west) side roof) dimensions of the roof should be should be assessed, in order to efficiency gain entered, as well as margins from the edge of the solar energy into electricity. On another the building. In this case, margins from west hand, flat roofs can be used for installing PV and south are set to 10 m, while margin from module in whole, but minimum distance east is set on 2 m in order to have clear between modules should be satisfied in order corridor, as entrance on the roof is from that to avoid shadings. Either flat or pitched roof side. Margin from north is selected as 0 m, as is used, special care for avoiding shading from another terrace is behind this one “Cover existing objects on the roofs (chimneys, roof” button will cover whole roof with PV antennas, walls, etc) as well as other nearby modules. With button Delete element one objects should be considered. single PV module can be removed, if needed In selected case, dimensions of the flat roof FIGURE 123.FIGURE 128. DISTIBUTION OF PV MODULES ON FLAT ROOF – MAXIMUM are 20 m in height (direction south-north) SIZE and 126 m in width (direction east-west). On flat roofs, PV modules are mounded on fixed structure included by optimal angle Modules should be placed in rows with distance in order to avoid shading in worst case (winter solstice – 21 December at 12:00). This distance is simulated in PV*Sol which gives distance between modules for selected case.
FIGURE 122.FIGURE 127. DISTANCE BETWEEN MODULES
Determination of the appropriate size of the With these parameters and selected PV PV system on roof is done in PV*Sol. Before modules, roof can be covered with 45 PVTRIN Training course- Solar installers handbook 152
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modules which total 1035 kW of installed objects are dangerous, as only partial shading capacity. As some countries have different of PV module affects work of whole array. groups of PV plants according to the size, Shading from trees should be also considered which receive different feed-in tariffs, size of with care, as trees are growing over the time. the PV array should be considered in this In PV*Sol, shading assessment is done either way. In this case, PV plants with installed under “Shade” window, either by defining capacity over 10 kW receive less feed-in tariff distance and height of surrounding object, than ones below 10 kW, thus two modules either by calculation of shadings from far are removed in order to meet 10 kW margin objects. Under the “List of objects” it is (not showed on figure). possible to define shading from surrounding In case of pitched roof, option “With objects by entering their height, distance and ventilation” or “Without ventilation” azimuth, which can be easily estimated on (according to the real process) should be the field. Two types of shading can be selected and only roof dimensions and selected: Building and Tree Also, by entering margins should be entered. points (azimuth, height) in solar diagram shading can be assessed. Easiest way to 6.6. Selection of an inverter determinate shading in this way is use of some shade analysis aids, such as Solar Inverter should be selected in order to match Pahtfinder. output values of PV system – output power, voltage and current. Under the Technical data FIGURE 124.FIGURE 129. EXAMPLE OF SHADINGS AT THE LOCATION Inverter PV*Sol would offer suitable 90° inverters for the system. In the case selected number of modules is 43 modules not any Sun's Course at its Highest Point inverter is found to match these array, thus number of modules should be selected on different number. With 42 modules, PV*Sol 45° Equinox offers various number of matching inverters 30° In this case, one inverter with 10 kW Sun's Lowest Position capacities is selected; however, various other 15° selections can be made. 0° -180° -90° 0° 90° 180° After the selection of inverter, under the North East South West North “Losses” button factors impacting production are entered, such as cable length or cable 6.8. Estimating a energy cross section. production With “Check” button PV*Sol check if any With all technical and climate parameters discrepancies are found. Parameters such as specified, performance of PV system can be Output check, MPP Voltage Check, Current simulated by pressing “Simulation” button Check and Upper Voltage Threshold Check After the simulation is done, several are performed. PV*Sol would signalize if any selections of results can be viewed: Economic of these parameters is out of suitable borders efficiency, Annual balance, Project report and 6.7. Estimation of shadings Graphics Shading can affect a performance of PV system. Especially, shadings from near PVTRIN Training course- Solar installers handbook 153
Graphics report allows seeing a distribution with all applicable Croatian and European of an energy produced, as well as other standards for such systems parameters of the system To ensure safe and continuous operation of FIGURE 125.FIGURE 130. PV systems throughF its lifetime, it is SIMUATION RESULTS - PRODUCTION OF ELECTRICITY necessary to provide complete protection
from lightning and induced surges already at
kWh % 1.500 12,00 the planning phase and implementation of 1.400 11,00 1.300 the project Protection must be provided not 10,00 1.200 1.100 9,00 only on the output side of the inverter, but 1.000 8,00 900 7,00 also on the output side of the PV modules 800 6,00 700 600 5,00 Photovoltaic systems are usually installed on 500 4,00 400 3,00 rooftops which represents a high probability 300 2,00 200 100 1,00 of lightning strike (ie lightning surge) In 0 0,00 Jan Mar May Jul Aug Oct Dec accordance with standard EN 62305-2 direct Time Period 1. 1. - 31.12. or not direct lightning strikes belong to Energy from Inverter (AC) 10.031 kWh Energy Produced by PV Array 10.411 kW expected risk of damage of a photovoltaic Array Efficiency 1. TG 11,3 % system 6.9. Safety plan of a small scale For this project, the photovoltaic system installation protection of atmospheric and induced surge was performed in accordance with European Preventing electric shock by working on de- Union standards EN 60364-7-712, EN 61 173 energized circuits is a key to electric safety and groups of standards EN 62305 With solar electric systems there are two Since the core of a photovoltaic system is the sources of electricity: the utility and the solar inverter, the protection from lightning and electric system Turning off the main breaker surge must be focused on the inverter, and at does not stop a solar electric system from the same time that protection includes the having the capacity to produce power entire photovoltaic system Photovoltaic installations can be made inherently safe, as can most building services Since the distance between the bus terminal installations, provided any hazards associated array of photovoltaic modules and inverter with their installation and use in buildings are more than 25 m, the surge arresters were adequately addressed installed at both places The following figure shows the performed situation of the PV The process of improving safety during system construction, operation and maintenance requires: • compliance with the requirements of the law, PV system codes and standards • following manufacturers’ recommendations • following best practice In this project, systematically applied safety and protective measures are in accordance
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Since the PV modules are mounted on the boundaries of possible deviations are factory roof with the existing lightning arrester set for each inverter and meet EU standards installation, damage of the PV system is minimized with permitted distance between the PV modules and lightning arrester installation This distance should be and is greater than 05 m When it is not possible to achieve the distance greater than 05 m, then it is necessary to conductively connected PV modules to the lightning arrester installation that is connected to grounding The purpose of this is that lightning currents can not flow through the structural framework of photovoltaic modules If the construction of PV modules is not conductively connected to the lightning arrester installation or the house does not have lightning protection installation, then it is necessary to directly connect the structure of PV modules to the grounding Grounding provides a rapid discharge of current in the surrounding soil Deeply stuck steel or copper rods or plates are used for grounding The inverter is protected by surge arrester on DC and AC side The surge arresters on DC side were selected according to the open circuit voltage of photovoltaic source Due to weather conditions, rainfall, solar radiation and high temperature, the photovoltaic modules are mutually connected with cable H07RN-F 20 Amp DC switches were used for the modules protection and 16 Amp and 25 Amp circuit breakers type B were used for the converter protection, as recommended by the manufacturer The minimum request to achieve parallel operation is set in a way that protection of the inverter start functioning (ie to act on switch) and insolate the PV system from the network if there is any frequency or voltage deviation (overvoltage or under-voltage) The
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MAINTENANCE AND TROUBLESHOOTING 7
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level of the system and therefore on the 7. MAINTENANCE AND electricity generation. The PV system can be inspected in a way through monitoring but TROUBLESHOOTING the annual site inspection is necessary to This chapter aims to provide valuable check each part of the system. For stand- information on the maintenance and alone systems, the installer should give some troubleshooting of the PV systems. instruction for actions to be done by the owner. 7.1. Maintenance plan For PV systems which are grid connected, 7.1.1. Periodical inspection energy production should be recorded (kWh, Amperes, Volts) and checked. These results, Photovoltaic systems have proved that they which should be sent to the installer need a very little maintenance, assuming that (depending also on their contract/ good design rules have been followed and agreement), can show a possible defect of the appropriate quality control procedures the system. Keeping monthly and yearly have been applied to the installation and records of the energy production is very commissioning process. Many installers and useful to confirm the proper operation of the PV owners claim that the PV systems are PV system. “maintenance free”. Nonetheless, photovoltaic systems require a periodical FIGURE 126.FIGURE 131. inspection to confirm that the system is KEEPING RECORDS FOR ELECTRICITY PRODUCTION FROM PV GRIT CONNECTED SYSTEM, CYPRUS. (Source: Cyprus Energy working properly and hasn’t performed any Agency) faults or failures. The frequency of the inspection and maintenance of the photovoltaic systems should be once annually. More specifically, at the first year of the operation of the PV system; the inspection can be performed more frequently because usually most of the problems are encountered in the beginning of their life. Nevertheless, the frequency of the inspection and maintenance is determined by the “maintenance contract” signed by the owner and the installer.
In the case of the stand alone PV systems, batteries require more maintenance which is depended on their type, the charge/discharge cycles and application. In the periodical inspection, a checklist has to be carried out 7.1.2. Dirt accumulation and followed for the whole installation to The most common maintenance task for solar check the performance of the parts of the modules is the cleaning of the glass area to system. A “small” fault in the PV system remove excessive dirt. The arrays are cleaned (especially on larger systems) may have when the temperature is not very high, obvious negative results on the performance
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typically at the morning or late in the 7.1.3. Battery maintenance afternoon. Regarding stand-alone systems, battery The layer of dust and dirt from the modules maintenance is maybe the most important can be removed by washing the module with task of maintenance. water. In most situations cleaning is only necessary during long dry periods when there FIGURE 128.FIGURE 133. BATTERY INSPECTION IN STAND-ALONE PV SYSTEMS, CYPRUS. is no rain to provide natural cleaning. (Source: Cyprus Energy Agency)
The frequency of cleaning depends on each installation’s conditions. For example, when a PV system is installed closed to a dusty area the arrays should be cleaned more frequently. At periods when rainwater is frequent, the dirt on the array is been cleaned from the rain and doesn’t need any further cleaning. In case of thick dirt on the The battery maintenance depends on the array’s surface, warm water or a sponge type, the charge/discharge cycles and could be used to remove the dirt application of the batteries. The two tasks accumulation. Any sharp tool or detergent which have to be ensured are the water should be avoided. additions and the performance checks. Performance checks may include specific FIGURE 127.FIGURE 132. gravity recordings, conductance readings, PERIODICAL INSPECTION PV GRIT CONNECTED ROOF SYSTEM, CYPRUS. (Source: Johnsun Heaters Ltd, Cyprus) temperature measurements, cell voltage readings, or even a capacity test. Battery voltage and current readings during charging can be helpful in determining whether the battery charge controller is operating properly. Flooded lead-antimony batteries require the most maintenance regarding water additions and cleaning. Sealed lead- acid batteries including gelled and AGM types remain relatively clean during operation and do not require water additions. Battery manufacturers provide maintenance recommendations for the use of their battery.
At the cleaning or at the annual inspection if any module has any obvious defect (e.g. 7.1.4. Inverter maintenance crack) this should be noted and monitored in order to ensure the right operation of the The main task regarding inverter array. The frames of the modules should be maintenance is checking its diagnostic inspected and observed for any defects. system. Especially when the inverter is installed into an internal space, the inspection and the cleaning of the inverter
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should occur more often. Thus, it is important 7.1.6. Maintenance tools and to check that the inverter is functioning equipment correctly by observing LED indicators, metering and/or other displays. Moreover, Multimeters and DC and AC clamp-on the area around the inverter should be kept ammeters are used for the measurement of clear to allow good air flow for proper the voltage and the current at the DC and AC cooling. Furthermore, checking several side. Also the multimeter can be used to inverter protections is important as well. check the connectivity of the cables during the installation. FIGURE 129.FIGURE 134. A portable instrument that measures INSPECTION OF INVERTERS IN GRIT CONNECTED ROOF PV resistance is used to measure grounding SYSTEMS, CYPRUS. (Source: Cyprus Energy Agency) resistance and insulation resistance of the cables.
A pyranometer or irradiance meter is used to measure sunlight irradiance. The pyranometer that is used by the PV troubleshooter will be an instrument that measures total irradiance on the array from all directions (i.e., direct and scattered). The pyranometer must be facing the same direction as the array to properly register the irradiance incident on the array. If the PV When an inverter breaks down and there is a array has multiple orientations, the irradiance “Guarantee” from its manufacturer, then, it must be measured for each orientation. should be replaced by the manufacturer in a few days. Very important are the terms and In the case of battery maintenance in the provisions included in the Contract between stand alone PV systems, a hydrometer is the installer and the owner. A clause should usually used to check the specific gravity of be added for indemnity in case of production the electrolyte in battery cells. The caps of losses and if the reparation takes more than a the cells are removed and the hydrometer is certain period (less than 48 hours), the used to withdraw electrolyte into the indemnity may be executed. hydrometer. The hydrometer incorporates a float that floats higher if the specific gravity is high and floats lower if the specific gravity is 7.1.5. Charge controller maintenance low. If the specific gravity is significantly lower in one cell than in the other cells of a Charge controller maintenance occurs during battery, it is an indication of a bad cell. If the same period with the other PV parts after a normal charging period, filling the cell inspection. It consists of diagnostic with distilled water and then applying an procedures and voltage testing. Charge equalizing charge to the battery does not controller instructions and displays should be increase the specific gravity, then the cell or followed. battery will need to be replaced. Additionally, protective mask, gloves and other protective equipment is used during the battery maintenance. PVTRIN Training course- Solar installers handbook 160
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An infrared camera (thermographic camera) should not install such system on his own can also be used during inspection and roof that might cause shading to the PV maintenance, in order to identify hot spots in array. the PV system (e.g. on cells, junction boxes,
PV panels). 7.1.8. Electrical connections check The electrical circuit should be checked at a 7.1.7. Shading regular basis (usually every 4-5 years) to The shading sources can be avoided during ensure that there are no problems with loose the design and installation of the PV system. connections, corrosion etc. Shading from other buildings or other equipment can be avoided from the early FIGURE 131.FIGURE 136. beginning. ELECTRICAL CONNECTIONS MAINTENANCE. (Source: Terza Solar Ltd) Usually when the PV array is placed on the roof shading sources related with vegetation, like trees, are more severe. However, the conditions might change if actions not taken to control the growing of trees, which can cause substantial loss of the energy generation of the system. It is not necessary to remove the trees or other vegetation but just to ensure that they stay low enough to prevent significant shading of the array.
FIGURE 130.FIGURE 135. POSSIBLE SHADING FROM GROWING VEGETATION. (Source: Terza Solar Ltd) 7.1.9. Other damages A PV system can be damaged from many unforeseen factors such as: Extreme weather conditions (earthquake, hail, storm, lightning, flooding, etc), fire, explosion, intentional act of third parties, sabotage, theft, biting of an animal, war, intentional acts of the owner, nuclear energy. Especially the lightning can cause damage to the PV modules and inverters. Surge arrestors on the DC side (and sometimes on the AC side) should be The owner of the system should understand installed for the protection of the inverters how important is the absence of shading and for lightning. Structures and PV module during maintenance – further to lowering the frames must be properly grounded. vegetation if any – is to observe any shading Photovoltaic insurances cover damages to equipment in the neighbouring roofs e.g. the PV system from several types of installation of aerials, TV satellite etc. unforeseen damage. Moreover, the owner has to understand that PVTRIN Training course- Solar installers handbook 161
7.2. Typical mistakes and Common Installation Mistakes with Module and Array Grounding: failures 1. Not installing a grounding conductor on Mistakes and failures in a PV installation can the array at all. be minimized by making the appropriate 2. Not connecting the different parts of the design, installation and maintenance of the modules together to achieve an equal PV system. Usually, in PV installations the potential grounding most mistakes occur during installation. 3. Using indoor‐rated grounding lugs on PV modules and support structures. Common Installation Mistakes with Array 4. Assuming that simply bolting aluminium Modules and Configurations frames to support structures provides 1. Changing the array wiring layout without effective grounding. changing the submitted electrical diagram. 5. Installing an undersized conductor for 2. Changing the module type or manufacturer grounding as a result of supply issues. 6. Not install a properly protection for 3. Exceeding the inverter or module voltage lightning due to improper array design. 4. Putting too few modules in series for Common Installation Mistakes with proper operation of the inverter during high Electrical Boxes, Conduit Bodies, and summer array temperatures. Disconnecting Means: 5. Installing PV modules without taking 1. Installing disconnects rated for vertical account the Impp of each module (grouping). installation in a non‐vertical application. 2. Installing improperly rated fuses in source Common Installation Mistakes with Wire combiners and fused disconnects. Management: 3. Covering boxes or conduit bodies making 1. Human mistakes regarding the wire them nearly inaccessible for service. connection during installation. 4. Not following manufacturer’s directions for 2. Not enough supports to properly control wiring disconnect in the DC side. cable. 5. Installing dry wire nuts in wet locations and 3. Conductors touching roof or other abrasive inside boxes that get wet routinely. surfaces exposing them to physical damage. 6. Using improper fittings to bring conductors 4. Not supporting raceways at proper into exterior boxes. intervals. 5. Multiple cables entering a single conductor Common Installation Mistakes with cable gland Mounting Systems: 6. Not following support members with 1. Not using supplied or specified hardware conductors. with the mounting systems. 7. Pulling cable ties too tight or leaving them 2. Not installing flashings properly. too loose. 3. Not using the correct roof adhesives for 8. Not fully engaging plug connectors. the specific type of roof. 9. Bending conductors too close to 4. Not attaching proper lag screws to roofing connectors. members. 10. Plug connectors on non‐locking 5. Not drilling proper pilot holes for lag connectors not fully engaged screws and missing or splitting roofing members. PVTRIN Training course- Solar installers handbook 162
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Typical Corrective measures and Some typical failures which are encountered failures troubleshooting in PV installations are listed in the following green light is on, or battery voltage is TABLE 27. On the right side column the measured at the terminals the possible reasons for these failures are controller may be damaged. reported and some corrective measures in Load not Check that no fuses are defective or order to trouble shoot them and put the operating circuit breakers have been tripped system in to operation. properly
Low voltage Shorten cables or use heavier cables, TABLE 27. shutdown recharge battery, allow unit to cool, TYPICAL FAILURES AND CORRECTIVE MEASURES AND improve air circulation, locate unit to TROUBLESHOOTING (Source: J N Karamchetti, Maintenance of cooler environment. Solar Photovoltaic & Renewable Energy Installations) Typical Corrective measures and Fault light on, AC AC products connected are rated at failures troubleshooting load not working more than the inverters power rating, overload shutdown has occurred The No current from Switches, fuses, or circuit breakers AC products connected are rated at array open, blown, tripped, wiring broken less than the inverters continuous or corroded power rating. The product exceeds Array current low Some modules shaded, full sun not the inverters surge capacity. available, Reverse Polarity Check connection to battery, the Array tilt or orientation incorrect, connection on inverter has likely been damaged and inverter needs to be replaced. Some modules damaged or defective, Modules dirty Loads Controller not receiving proper disconnecting battery voltage, check battery Battery is not Measure PV array open circuit voltage improperly connection. Adjustable low voltage charging and confirm it is within normal limits. disconnect is set too high. Reset If voltage is low or zero, check the adjustable low voltage disconnect connections at the PV array itself using a variable power supply, Disconnect the PV from the controller when working on the PV system Array fuse blows Array short circuit test performed with Measure PV voltage and battery battery connected. Disconnect battery voltage at charge controller terminals to perform test. Array exceeds rating if voltage at the terminals is the same of controller, add another controller in the PV array is charging the battery If parallel if appropriate or replace with PV voltage is close to open circuit controller of higher capacity. voltage of the panels and the battery Loads Controller not receiving proper voltage is low, the controller is not disconnecting battery voltage, check battery charging the batteries and may be improperly connection. Adjustable low voltage damaged disconnect is set too high. Reset Voltage is too Disconnect PV array, disconnect lead Adjustable low voltage disconnect high from the battery positive terminal and using a variable power supply. leave PV array disconnected. The Array fuse blows Array short circuit test performed with green charging light on charge battery connected. Disconnect battery controller should not be lit. Measure to perform test. Array exceeds rating the voltage at the solar panel of controller, add another controller in terminals of the charge controller. If PVTRIN Training course- Solar installers handbook 163
Typical Corrective measures and failures troubleshooting parallel if appropriate or replace with 7.3.2.3. Displays controller of greater capacity. Displays are the backbone of monitoring. The easiest to fit is a simple indication as part of No output from Switch, fuse or circuit breaker open, the inverter. Most PV inverter manufacturers inverter blown or tripped or wiring broken, offer an optional display. However this can corroded. place severe constraints on the placing of the
Low voltage disconnect on inverter or inverter, which would normally be in a roof charge controller circuit is open, void, electrical switch room, or some other secluded place. If the display is to be effective High battery voltage. it must be in a place where it is visible in everyday activities. Remote displays are easier to site, and may be provided with data 7.3. Diagnostic procedures from the inverter itself, or by a meter in the cabling from inverter to distribution board. A 7.3.1. Visual inspection procedures significant cost to installing this is the routing of the cabling to the display, but there are The mechanical problems are generally instruments on the market that avoid this by evident by something being loose or bent or utilizing short-range radio transmission. broken or corroded, can generally be found with a visual check. The instructions given in There are many different formats of data that the previous paragraphs should be followed. can be displayed: the most popular are the instantaneous power being generated, and 7.3.2. Performance monitoring the total energy to date. However, large 7.3.2.1. User feedback displays often include derived values that mean more to the public, such as numbers of This can range from a simple LED on the lights that are being powered, or the amount inverter lid or a user display in a domestic of carbon production being offset. A corridor, to a large interactive wall display in computer-based monitoring system can often the entrance hall of a corporate building. All embed that information within a touch displays provide the users an indication that screen driven information point, or to have it the system is functioning. A clear display displayed on the website for the building. gives much added value to the system, especially if combined with some graphic or text explaining the concepts. 7.3.2.4. Data Acquisition Systems 7.3.2.2. Performance verification The main system tends to fall into two types: loggers and computers. The advantage of a A system may have been financed on the logger is its simplicity and robust basis of its output through support schemes construction, but its disadvantage is its (Feed-in Tariffs), and so the user is good to inflexibility and cost. A computer system, in measure the output and compare to the contrast, may be slower to set up and claims for the system. The complexity and commission, but has the advantage of a expense of such metering is determined by wider choice of operational modes and the number and accuracy of the custom settings, while the cost may be less measurements to be made. for a system based on a desktop PC. The PVTRIN Training course- Solar installers handbook 164
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choice between the types may well be creation of a detailed maintenance checklist dictated by the type of monitoring strategy. is necessary for this purpose in order to ensure the good operation of the system. A maintenance checklist should include several 7.3.2.5. Sensors checks as given in Error! Reference source There is no limitation to the inputs that may not found.TABLE 25 below. be monitored for a PV System, but most systems will need to measure the input and TABLE 28. MAINTENANCE CHECKLIST (Source: output energy, and some environmental and http://wwwcontractorsinstitutecom/) system variables. Array Installation and Inverters Wiring Condition Listed inverters (type, serial 7.4. Documentation to the Proper insulation on number, configuration) module wiring Status/Condition customer Proper connectors on Defects founded array wiring extensions Noise levels Proper grounding of array Open circuit voltage (V) After the installation has been completed, & array mount Impp (A) the installer tests and checks the system Grounded conductors Input and output extensively and records the results of the installed disconnects labelled Array mount properly Proper wire sizes test on a commissioning report. This process secured and sealed Grounded can take from few days to several days Suitable transition from depending on the size of the PV installation. open wiring to enclosed wiring This will be signed by an authorized signatory Metallic conduit through to confirm the work is satisfactory. attics to array disc Damages of modules observed A copy of the commissioning report should be Dirt accumulation given to the owner together with relevant observed Shading observed on conformity certificates and guarantees. modules Guarantee for each system parts are given to the owner (usually manufacturer’s DC Connections Batteries (Battery warranties). Also full operating and backup systems only) Source Circuit Combiner Terminals protected from maintenance instructions should be given, Boxes shorting along with a full description of the system. DC-rated circuit breakers Cables properly terminated or fuses with adequate (no set screw lugs on fine voltage rating stranded wire) Usually the owner asks some performance Listed equipment Maintenance-free vented guarantees for the system from the installer. for cooling Flooded vented to outside The installer makes a commitment for the Labeled with proper safety yearly energy production of the system by procedures giving a minimum kWh produced per year. If DC Component Charge Controllers the real energy production is lower than the Enclosures (Battery backup systems given, then the installer has to compensate only) the owner (investor), depending on the terms Proper conductor sizes Status/Condition and insulation types Input and output of the agreement. Proper conductor disconnects labeled terminations Listed charge controllers 7.5. Maintenance checklist DC ratings on DC Proper wire sizes components Grounded A PV system field inspection and Listed equipment maintenance should be carried out. The SINGLE POINT PVTRIN Training course- Solar installers handbook 165
GROUNDING! d. measure the individual module voltages in Optional grounding electrode conductor this source circuit AC Component Standby Circuits Enclosure (Battery backup only) 3) What preventions should be taken to Isolated Neutral busbar Watch for multiwire if 120V ensure the appropriate operation of the Listed components Labeled inverters? Labeled disconnects and C/B 4) Which instrument is used to identify hot
Utility Disconnect Point of Utility spots in the PV system? Give some examples Connection of PV system’s parts that could be inspected Labeled Labeled with this instrument. Visible, lockable, Compliance accessible, load break, 5) After the PV installation has been external handle completed what are the tests and checks
Building Main Handover of PV system that must be done and which Disconnect documentation and guarantees should be Labeled Mentioned faults delivered to the owner.
6) Could you estimate the annual energy production of a 3 kWp mono-crystaline PV 7.6. Exercises installed in Nicosia, Cyprus at 27o with efficiency 13% after one year of operation, 7.6.1. Questions & Answers when a. cleaning instructions were followed 1) When connecting and disconnecting wires while troubleshooting a PV system, the best b. without any cleaning way to avoid electrical shock is to: c. shading of a module a. inspect all questionable terminals, wear rubber gloves and turn off all switches b. keep one hand behind your back, with all switches turned off and only touch grounded surfaces c. turn off switches, measure voltages and currents, and wear protective equipment d. wear shoes with soft rubber soles, turn off all switches, and don’t touch metal surfaces 2) If the current in one source circuit is significantly lower than the currents in the remaining source circuits of a PV array, and all modules are in full sun, then without disconnecting any conductors, an appropriate follow-up test is: a. measure the individual module currents in this source circuit b. measure the voltage at the inverter input c. measure the short circuit current of this source circuit
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process and write down exactly how you wish 8. QUALITY MANAGEMENT to handle it. AND CUSTOMER CARE For example, when a new enquiry is received, it is essential to capture certain details eg 8.1. Quality principles contact details, location & post code, basic customer requirements, roof orientation and Once best practice has been established pitch (if possible), etc If there is a standard within an installation company, it is essential form to fill in, the job of capturing this to be able to install systems to the same information may be delegated to non-expert consistently high standard. This is where a staff. However, if there is no form, it will Quality Management System (QMS) can help. generally fall to an expert to have the phone The essential idea is that the whole process, conversation with the prospective customer, from first customer contact through quoting, thus occupying valuable time of the expert to installation, commissioning and hand-over, is perform a task which could be covered by set out in a written plan which the installer lower cost staff This is just one example of would like to use for all installations. how the very first stage of the selling/installation process can be made more The standard forms, procedures and software consistent, efficient and lower cost by use of programs that make up the QMS can all a standardised process. contribute to consistency of operation and traceability. Traceability becomes important So, by thinking through each stage and in the event of a problem after writing down the procedure to be followed, commissioning, perhaps many months or the QMS is built up. The QMS could also be years later It helps the installer understand thought of as a set of ‘Operating Procedures’. where the process went wrong, or proves The list below is an example of some of the that the installer did not make any mistakes items which could be considered when and the fault lies elsewhere (particularly writing operating procedures to be included useful if the complaint progresses to a legal in the QMS for a solar installation company: challenge). • Procedure for processing customer ISO 9001 is an example of a quality enquiries, possibly using a standard management system used by many medium ‘Customer Enquiry’ form (as discussed in and large sized companies and can act as a example above). useful guide for anyone considering how to • Procedure for conducting site surveys. set up a QMS for their own business. This may also include details of how to However, it is important to remember that complete a ‘Site survey’ or ‘Building every business is different and so each Assessment’ form. business must develop its own QMS which is • How to prepare a quotation, including best suited to its activities. It is not necessary completing a quotation template. to implement a full ISO 9001 system in order • The standard customer contract to be to set up a basic QMS. A cut-down version used. may be more suitable for smaller companies • The standard sub-contractor contract and sole traders. template for employing subcontractors. One method of defining and implementing a • The procedure to be used for designing QMS is to think through each stage of the systems and the software tools to be used eg software for mechanical and
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electrical design calculations and energy • A complaints procedure and log of all predictions. complaints received (whether • Procedure for completing site-specific substantiated or not) to record risk assessments and/or method individual instances of issues and, if statements. This could also include an appropriate, how these were resolved. appropriate template. • Procedure for inspecting delivered It is also most helpful to write an overview goods (eg for correctness, damage, document of the QMS to say which of the missing parts or documentation etc). procedures will be used at each stage from • Procedure for reviewing the contents of customer contact to hand-over and after the QMS, including defining when and sales service. This should include defining how the documents are updated and who is competent to complete each who is responsible for this. procedure. This is sometimes known as a • Other documents that should be Quality Plan, although the name is not contained in the QMS include: important. • A document identifying the relevant
national. Technical Regulations, Building Once a QMS has been established it is Regulations and industry guides. generally worthwhile reviewing how well it is • Product Manufacturers’ instructions for operating on a regular (eg quarterly) basis, each of the PV products installed by the and recording the outcome of each review. company. This ensures that previous mistakes are not • List of documents to keep in each repeated and that good practice is identified customer’s job file. and included in the day to day operation of • List of documents to hand over to each your business. Such reviews also provide an customer. opportunity to check for changes in • Standard terms and conditions (if not regulations and standards that are relevant to included in the contract) and standard PV installations, to look at any complaints warranty information. received so that common causes can be • Health and Safety Policy. identified and put right and to receive
feedback from staff/sub-contractors. Other documents which may be used occasionally and which could also be contained in the QMS include: 8.2. EU standards for PV
• A list of equipment (including serial There are numerous EU standards for PV numbers) which requires calibration, which contain the requirements for who is responsible for ensuring the manufacturing and testing PV products. equipment is calibrated and dates for These standards are also updated from time when the next calibration is due. to time, or new standards are published, to • Staff Training Records - useful for take account of changes in technology and recording who is competent to operate testing methods. Consequently it is not each procedure and to have a visible practical to provide a comprehensive list of skills improvement path to help standards here. A list of standards is provided motivate staff and plan workforce in Annex iii and an extensive list of standards requirements. may also be found on the European Photovoltaic Industry Association website PVTRIN Training course- Solar installers handbook 169
(wwwepiaorg). Although there are many and a written acceptance of the quotation standards covering PV products those which has been received by the installer. define the requirements for module qualification and type approval include: 8.3.2. Selling Solar • EN 61215 (for crystalline PV modules) The following points should be adhered to during the pre-sales process: • EN 61646 (for thin film PV modules) Advertising • EN 61730 (PV module safety) Advertising and promotional activities will It is often an eligibility requirement (eg for portray the products and services fairly and financial incentives) that any PV modules will not make unsupported claims for installed be certificated according to the performance or financial returns. requirements of at least one of the standards listed above. Staff Training Although not a European Standard the MCS Sales staff will be trained to a level enabling installation standard for microgeneration PV them to perform a detailed solar survey and systems (MIS 3002) specifies the provide advice on any required upgrade of requirements for the design, supply, services. They will also be competent to installation, set to work and handover of PV provide a basic building energy survey and systems for permanent buildings. advice on energy efficiency. MIS 3002 is available from the MCS website Training for sales staff will include a module (wwwmicrogenerationcertificatonorg). on acceptable selling techniques in order to avoid the use of high pressure sales tactics MIS 3002 also calls upon guidance contained Staff should be briefed on the likely sanctions in ‘Photovoltaics in Buildings – Guide to the should any member be found to be using installation of PV systems’ which is currently such tactics. in its 2nd edition but will shortly be updated. In general sales staff:
- May not offer incentives for signing a 8.3. Customer care contract during the initial sales meeting. - May not remain on the property for more 8.3.1. General than a period of 2 hours, including surveying time. It is important that the whole process from first customer contact, through to - May not accept any payment at the initial commissioning and hand-over of the system, sales visit. is clear, transparent, documented and - Must inform the customer of the sales understood by the customer. Departing from process (see Quotations below), including this general principle will inevitably result in the ‘cooling off’ period subsequent to problems and complaints. signing of a contract. Therefore all stages of the process must be - Must inform the customer of any documented in a form that the customer can permissions or approvals needed (eg understand, all key points should be planning permission, grid connection) explained verbally and the project must not before the installation begins and make it proceed until the customer is comfortable clear who is responsible for obtaining these.
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8.3.3. Quotations and contracts Other items which should be supplied at the quotation stage are: Energy Yield Estimates
The quotation, together with your terms and - An explanation of any financial incentives conditions of business, will often form the (eg feed-in tariffs, grants, etc). contract between you and your customer. It is therefore essential that quotations are - The resulting value for money of the clear, easily understood and contain all the proposed system, including advice that the necessary information. inverter may need replacing during the lifetime of the system and the approximate cost of this. Even before a quotation is issued it is good - List of all the main components to be practice to provide your customers with an supplied, including make and model estimate of the annual energy performance numbers. of the proposed PV system. This is because - Expected duration of the installation the generation of energy from a renewable process. source (and the receipt of any associated financial incentives) is usually the main - Allowed “cooling off” period (this may vary objective for the customer. Thus providing a according to local legislation or codes of reasonably accurate estimate of the practice). predicted energy performance of the system - What to expect during the installation eg. before entering into any contract for - Scaffolding. installation is of key importance. - Any services required (eg power). Such energy yield figures can only ever be - Any temporary storage space required for approximate and the calculation can become securely storing equipment prior to fitting. very complex, depending on the level of - Forms of payment which are acceptable and accuracy required. Thus, it is important to payment terms. explain to your customer the key factors: climate, orientation & tilt, shading, - Your other terms and conditions of temperature and to state what method of business. calculation has been used (whether by manual means or by use of a software If a deposit is required before installation modelling package). The key assumptions work starts, this will constitute a small part of behind the calculation should also be the total value of the project. The deposit and presented to allow checking of the estimate It any other advance payment, if required, is also essential, not least for your own should be kept in an account specially set up benefit as the installer, to accompany any in the customer’s name (eg a 'client' or other estimate of performance with a disclaimer third party account). This must be separate that explains that the performance of a PV from those accounts linked to the installer’ system cannot be predicted accurately own credit and banking facilities. Guidelines because of the variation in the amount of for setting up and administering these solar energy available from location to arrangements are available from most banks. location and from year to year. The deposit will be returned to the customer in the event of cancellation during the cooling off period (see below). Other items on the quotation PVTRIN Training course- Solar installers handbook 171
In the event of small change to the 8.3.5. Final testing, commissioning and specification, these must be agreed in writing handover with the customer In the event of large changes to the specification, by either party, At the end of the installation process, the then a new quotation must be produced and final stage is testing and commissioning. This accepted before work may continue. stage will follow the installer’s written test and commissioning procedure, including 8.3.4. Completing the work those specified in the PV equipment The installation stage may only proceed after manufacturer’s installation instructions,and a the written acceptance of the quotation (in copy of the results must be supplied to the the event of multiple quotations, it will be customer. made clear to which quotation the After the commissioning of the system, a acceptance refers). Also, the installation certificate must be provided to the customer should not begin until the installer has seen showing the following things: evidence that all necessary permissions and approvals have been obtained. - property address - installer contact details If subcontractors are employed, these will at all times be under the supervision and control - type & serial numbers of equipment of the installer who has the contract with the installed customer. The installer remains responsible - date of commissioning to the customer for the quality and - rated power of system correctness of any subcontracted work. - annual energy yield estimate During Installation - installer warranty period (ref terms) Customers and their premises must be - PV module & inverter manufacturer treated with respect at all times. Precautions warranties must be taken to minimise any noise, Declaration: “This installation has been disturbance or damage to the property (eg commissioned by…
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Installers should offer a maintenance • A health and safety policy for your contract, but not insist that it is taken up It is business good practice to leave a copy of a user • A complaints handling procedure manual on site, which details the maintenance requirements of the system.
All installers shall have and operate a transparent complaints procedure and a written copy of the process shall be left with the customer. A useful tool for the installer to monitor customer satisfaction, and to help reassure clients, is a feedback form It is therefore good practice to include one of these in the customer’s hand-over pack. 8.4. Exercises To help you develop a QMS that is appropriate to your own business review the text in this chapter and use the guidance contained in it to prepare the following:
• A ‘Customer Enquiry’ form • A ‘Site survey’ or ‘Building Assessment’ form • A quotation template • A standard customer contract • A standard sub-contractor contract • A standard procedure for designing PV systems • A risk assessment form • A generic method statement • A goods-in inspection form • A procedure for reviewing the contents of your QMS • A list of relevant national Technical Regulations, Building Regulations and industry guides • A list of documents to keep in each customer’s job file • A List of documents to hand over to each customer • Standard terms and conditions (if not included in the contract) and standard warranty information
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The PV technician can gain specialized 9. FURTHER READING knowledge on battery technology and charge control strategies commonly used in stand- 9.1. Further Reading alone PV systems. Details are provided about the common types of flooded lead-acid, valve 1 Drifa M, Pereza PJ, Aguilera J, Aguilar JD, A regulated lead-acid, and nickel-cadmium new estimation method of irradiance on a cells. Comparisons are provided for various partially shaded PV generator in grid- battery technologies, and considerations for connected photovoltaic systems, Renewable battery subsystem design, auxiliary systems, Energy vol33, pp 2048–2056, 2008 (relevant maintenance and safety are discussed. §213)
The PV installers can study a new method for estimating the irradiance on a partially 5 Danish Energy Agency, Optimisation of the shaded PV system. The principles of the Design of Grid-Connected PV Systems under proposed method and the algorithm used for Danish Conditions” (PV-OPT), 2009 (relevant calculating the irradiance on shaded planes is §231) presented . The trainee can study several case studies the design of several case studies in order to comprehend the theory presented in chapter 2 Haeberlin H, Optimum DC operating 2 3 examples are provided on designing of a Voltage for grid connected PV plants, 20th PV plant on a roof of a single house, using European PV Solar Energy Conference, products commercially available. In the Barcelona, Spain, June 2005 ( relevant §222) examples the expected annual yield is The technician may find answers to questions calculated using 3 different methods. A like at which VMPP an inverter should be manual calculation based on data sheets for tested and in which interval the STC array modules and inverter, the web‐based voltages of a PV plant should be chosen. The software program PVGIS, and the software design procedure is also presented in the system PVSYST. The trainees can study document by some numerical examples. practical examples.
3 IEA PVPS, International Energy Agency 6 P Arun, R Banerjee, S Bandyopadhyay, Implementing Agreement on PV Power Optimum sizing of photovoltaic battery Systems, Use of PV Power Systems in Stand- systems incorporating uncertainty through Alone and Island Applications, 2003 design space approach, Solar Energy PV installers can deepen their knowledge in vol 83, pp 1013-1025, 2009 (relevant §2210) common practices and practical techniques The trainee can study a methodology for the to set up lightning protection (relevant §228). optimum sizing of PV battery system for remote electrification. The proposed 4 Dunlop J P, Batteries and Charge Control in methodology is based on the design space Stand-Alone Photovoltaic Systems. approach involving a time series simulation of Fundamentals and Application. Sandia the entire system. National Laboratories USA, 1997 (relevant §2210)
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7 L Lu, HX Yang, Environmental payback time anti-islanding methods are evaluated and analysis of a roof-mounted BIPV system in compared through experimental results. Hong Kong, Applied Energy vol 87, 3625-3631, 2010 (relevant §241) 11 X Gong, M Kulkarni, Design optimization of The energy payback time and greenhouse-gas a large scale rooftop PV system, Solar Energy, payback time of a rooftop BIPV system (grid- vol 78, pp 362-374, 2005 (relevant §271) connected) in Hong Kong is investigated in Optimization of PV systems is an essential order to measure its sustainability. issue when designing a system, the technician may study the optimization process of a grid connected PV system, on the rooftop of a 8 EPIA, Solar generation 6; Solar Photovoltaic Federal office building is presented and a PV Electricity Empowering the World, 2011 energy conversion model is described. Based (relevant §242) on this model, array surface tilt angle and The PV technician can collect valuable market array size are optimized. The optimization information from the current status of PVs method is based on maximizing the utilization worldwide and also be informed for of the array output energy, and, at the same environmental issues and for the potentials time, minimizing the electricity power sold to and growth prospects in the coming years. grid. This information can be valuable in discussions with potential clients. 12 A Salaymeh, Z Hamamre, F Sharaf, MR
Abdelkader, Technical and economical 9 M A Eltawil - Z Zhao, Grid-connected assessment of the utilization of photovoltaic photovoltaic power systems: Technical and systems in residential buildings: The case of potential problems—A review, Renewable Jordan, Energy Conversion and Management, and Sustainable Energy Reviews vol 51, pp 1719-1726, 2010 (relevant §271) vol14, pp 112-129, 2010 The trainee can study a case study which The paper reviews the literature on expected deepens in the the cost of a PV system and potential problems associated with high the payback period. The feasibility of utilizing penetration levels and islanding prevention PV systems in a standard residential methods of grid tied PV. According to the apartment in Jordan is presented. An survey, PV grid connection inverters have apartment is chosen as a case study to fairly good performance. conduct energy and economic calculations. The electrical power needs and cost are calculated for the apartment. 10 B Yu, M Matsui, G Yu, A review of current anti-islanding methods for photovoltaic power system, Solar Energy 13 SEAI, Sustainable Energy Authority of Ireland, Best Practice Guide– PVs, Ireland, vol 84, pp 745-754, 2010 2010 (relevant §271) The technician can be informed in different The PV technician can study the preliminary anti-islanding method developments for grid- design of a BIPV system. The case study connected PV power generation based on describes the design and planning of a PV single phase system. The active and passive
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installation, including the integration of PV into the building.
9.2. Further Reading, in Greek 14 NABCEP, North American Board of Certified Energy Practitioners, NABCEP study 1 Οδηγίες για την εγκατάσταση Φ/Β guide for photovoltaic system installers, USA συστημάτων σε κτιριακές εγκαταστάσεις, 2009 (relevant §272) ΚAΠΕ, 2009 Different questions and answers are The manual titled is available on the website presented in this document that can be of CRES and summarized information for the helpful for the trainer to test his knowledge PV installation in buildings is provided to on different PV issues. The answers are also professionals. presented in the same document.
2 Μηχανική των Φωτοβολταϊκών Photovoltaics in Buildings Guide to the Συστημάτων, Τεχνολογία, Μελέτες, Installation of PV Systems 2nd edition 2006 Εφαρμογές, ΣΝ Καπλάνης, Εκδόσεις ΙΟΝ (DTI publication DTI/pub URN 06/1972). (3rd 2004 edition to be published shortly). Available Plenty of PV exercises and examples for the from trainee to comprehend the theory and the www.bre.co.uk/filelibrary/pdf/rpts/Guide_to design issues presented in chapter 2. _the_installation_of_PV_systems_2nd_Editio n.pdf
BRE Digest 489 ‘Wind loads on roof-based photovoltaic systems.’ Available from www.brebookshop.com
BRE Digest 495 ‘Mechanical installation of roof-mounted photovoltaic systems.’ Available from www.brebookshop.com
‘Photovoltaics in Buildings – Safety and the CDM Regulations’, (BSRIA/DTI February 2000, ISBN 086022 548 8
Solar Energy in Buildings, published by SEC. Authors: A. Dobrinova, S Shtrakov, A. Penchev, 2001
Detailed information on solar radiation and climate in Bulgaria. Detailed information on building orientation.
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10 GLOSSARY OF TERMS
Building applied photovoltaics: PV 10. GLOSSARY OF TERMS installations fixed over the existing elements of buildings’ envelope as roof, skylights, A facade, balconies and shelters. Alternating current: electric charge Building-integrated photovoltaics: PV periodically reverses direction. In (DC), the materials (sheets, tiles, glasses, etc.) used flow of electric charge is only in one instead of conventional building materials in direction. parts of the building envelope. Ampere: unit of electrical current or rate of Bypass Diode: a diode connected in parallel flow of electrons. One volt across one ohm of with a PV module to provide an alternate resistance causes a current flow of one current path in case of module shading or ampere. failure. Amorphous semiconductor: non-crystalline semiconductor material, easier and cheaper C to make than crystalline, but less efficient Cadmium (Cd): chemical element used in Ampere Hour: a measure of current over making certain types of solar cells and time, commonly used to measure battery batteries. capacity. Cadmium Telluride (CdTe): a polycrystalline Azimuth: Angle between the north direction thin-film photovoltaic material. and the projection of the surface normal into Charge controller: device regulating the the horizontal plane measured clockwise voltage and current coming from the solar from north panels going to the battery. B Clamp-on ammeter: An electrical meter with integral AC device having two jaws which Balance-of-system (BOS): all of the PV open to allow clamping around an electrical system components except from the PV conductor. modules. It is the auxiliary equipment which is related to supporting and security Conversion efficiency: The ratio of the structures, inverters, disconnects and electric energy produced by a PV device to overcurrent devices, charge controllers, the energy from sunlight incident upon the batteries, and junction boxes cell. Battery: electrochemical cells enclosed in a Converter: device that converts a dc voltage container and electrically interconnected in to another dc voltage. an appropriate series/parallel arrangement to Crystalline silicon cells: made from thin slices provide the required operating voltage and (wafers) cut from a single crystal or a block of current levels. silicon. Battery bank: group of batteries connected Current-voltage: the applicable combinations together to store energy for a PV system. of current and voltage output of a PV panel. Blocking diode: device that controls current D flows inside the PV system, blocking reverses leakage current backwards through the Depth of discharge: the ampere-hours modules. removed from a fully charged cell or battery, expressed as a percentage of rated capacity. PVTRIN Training course- Solar installers handbook 177
Diffuse Irradiance (DIF): the amount of Equipotential Zone: temporary protective radiation received per unit area by a surface grounds placed and arranged in such a way that does not arrive on a direct path from the that will prevent each worker from being sun, but has been scattered by molecules and exposed to hazardous differences in particles in the atmosphere or reflected by potential. the ground and comes equally from all Equivalent carbon dioxide: emissions of directions. greenhouse gases expressed kgCO2e. Diode: An electronic device that allows current to flow in one direction only. F Direct-current: electric charge in one Feasibility Study: report for the viability of a direction. project, with an emphasis on identifying potential problems and risks and highlight the Direct Normal Irradiance (DNI): the amount prospects for success of solar radiation received per unit area by a surface that is always held perpendicular (or Feed-in-Tariff: mechanism designed to normal) to the rays that come in a straight accelerate investment in RES, by offering line from the direction of the sun at its long-term contracts to producers. current position in the sky Filling factor: factor informing of the extent Distributed system: A power generating to which a module deviates from the ideal system that is installed where the energy is operation. needed. Fixed Tilt Array: a photovoltaic array set in at E a fixed angle with respect to horizontal. Fuse: electrical protection device that break Earthing system: is the total set of measures the electrical circuit if too much current is used to connect an electrically conductive present part to earth. Electric Current: the flow of electrical energy G (electricity) in a conductor Gallium (Ga): chemical element, metallic in Electric Circuit: path followed by electrons nature, used in making certain kinds of solar from a power source (generator or battery) cells and semiconductor devices. through an external line Gallium Arsenide (GaAs): a crystalline, high- Electrolyte: medium that provides the ion efficiency compound used to make certain transport mechanism between the positive types of solar cells and semiconductor and negative electrodes of a battery. material. Encapsulation: protection placed around the Global Horizontal Irradiance: the total cells when modules are made, designed to amount of shortwave radiation received from last for over 20 years. above by a horizontal surface. It includes both Direct Normal Irradiance and Diffuse Energy Pay-Back Time: the time in which the Horizontal Irradiance. energy input during the PV system life-cycle (production, installation, disassembling and Global In-Plane Irradiance: the total amount recycling) is compensated by electricity of radiation (both DNI and DIF) received from generated by the PV system. above by an inclined surface.
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Grid: Transmission line network used to maintain a supply of electricity to that section distribute electric power. of the grid or to a consumer’s installation. Grid-connected system: PV system connected Isolating transformer: the input and output to the local electricity network windings of the transformer are electrically separated by double or reinforced insulation. Grounding conductor: conductor used to connect the frame of an electrical device to J earth ground. The grounding conductor is often copper. Junction Box: an enclosure on the module where PV strings are electrically connected Grounding system: see Earthing system and where protection devices can be located. H K Hot spot: phenomenon of PV device kilowatt hour: a unit of energy equal to 1000 operation where one or more cells within a watt hours or 3,6 megajoules. PV module or array act as a resistive load, resulting in local overheating or melting of L the cell. Learning curve: a graph presenting the rate Hybrid System: mix of energy generations of learning. In PVs is often related to the that may include conventional generators, world PV production the price cogeneration, wind turbines, hydropower, Life Cycle Analysis: assessment to quantify batteries, PVs, fuel cells, hydropower, and evaluate the environmental burdens (air biomass and other inputs. emissions, water effluents, solid waste, and I the consumption of energy and other resources) over the life cycle of a product, Inclinometer: device for measuring angles of process, or activity. slope and inclination of an object with respect to its gravity by creating an artificial M horizon. Maximum power-point tracker: component Ingot: molten and subsequently solidified of a PV inverter which functions as an optimal silicon cubes or cylinders, ready for cutting electrical load for PV modules. into wafers Metering: the system includes meters to Internal Rate of Return: the actual annual provide information about the general rate of profits on an investment. It equates performance. Some meters provide an the value of cash returns with cash invested. indication of the home energy usage too. Inverter: a converter which transforms DC Mismatch losses: losses caused by the voltage and current from PV modules into interconnection of solar cells or modules single or multiphase AC voltage and current. which do not have identical properties. Irradiance: the instantaneous intensity of MPP regulator: device searching for the best solar radiation on a surface (W/m2). operating point of a module and ensures that the module delivers the maximum possible Islanding: any situation where the grid power under all conditions. electricity is off-line and one or more inverters from a grid-connected PV system Multimeter: device that can measure voltage, current and resistance. PVTRIN Training course- Solar installers handbook 179
N Pyranometer: device used to measure broadband solar irradiance on a planar Nominal Voltage: a reference voltage used to surface. The solar radiation flux density describe batteries, modules, or systems measured in W/m2 O Q One-axis tracking: a system capable of Quality management system: organizational rotating about one axis, usually following the structure, and processes to implement sun from East to West. quality management. Open circuit voltage: voltage produced by PV R with no load applied when the cell is exposed to STC. Regulator: device to prevent overcharging of batteries by controlling charge cycle-usually P adjustable to conform to specific battery Parallel connection: interconnection of two needs. or more panels, so that the voltage produced S is not increased and the current is additive. Safety plan: a list the basis for health and Peak (Maximum) Power Point (MPP): The safety during the construction phase. point on the I-V curve’s knee where the maximum power output is achieved Semiconductor: A material with a crystalline structure that will allow current to flow under Peak Sun hours: The equivalent number of certain conditions, making it a good medium hours per day when solar irradiance averages 2 for the control of electrical current. 1 kW/m . Series connection: interconnection of two or Performance ratio: the performance of the more panels so that the voltage is additive system in comparison to lossless system at but the same current passes through them. the same design and rating at the same location. Series Controller: A controller that interrupts the charging current by open-circuiting the Personal Protective Equipment (PPE): PV array. The control element is in series with equipment used to reduce employees the PV array and battery. exposure to hazards when engineering and administrative controls are not feasible or Shunt Controller: charge controller that effective. redirects or shunts the charging current away from the battery. Protective earthing: network of conductors transferring the currents related to safety to Silicon: A non-metallic element, sensitive to the main earth terminal. light and capable of transforming light into electricity. Silicon is the basic material of PV array: PV modules linked together most beach sand, and is the raw material PV phenomenon: creation of a voltage in a used to manufacture most PV cells. material exposured to light Solar Spectrum: The total distribution of PV module: PV cells wired in series and electromagnetic radiation emanating from enclosed into a protective case. the sun.
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Stand-alone PV system: autonomous PV Zenith: imaginary point directly above a system not connected to the grid. particular location, on the imaginary celestial sphere Standard test conditions: radiation: 1000W/m2, temperature: 25°C, and air mass: Zenith angle: the angle between the 1,5. direction to the zenith and the direction of a light ray. Stratification: the condition when the acid concentration varies from top to bottom in the battery electrolyte. String: number of modules or panels interconnected electrically in series to produce the operating voltage required by the load. Sulfation: the formation of lead-sulfate crystals on the plates of a lead-acid battery. T Thermomagnetic switch: is a current limiter (electromechanical device) that prevents to exceed the hired power. Tracking system: system that traces the position of the sun during the day so that sunrays hit the panel at right angles, and its efficiency is improved. V Volt (V): unit of electrical force equal to that amount of electromotive force that will cause a steady current of one ampere to flow through a resistance of one ohm. Voltage: The amount of electromotive force, measured in volts, that exists between two points. W Wafer: thin sheet of semiconductor Watt: unit of power in the International System of Units. Winter Solstice: the shortest day and the longest night of the year, the sun's daily maximum position in the sky is the lowest. Z
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Imax INV maximum permitted DC input A ANNEXEX current of the inverter
In string nominal string current A i. Abbreviations and Acronyms In String fuse trigger current of the string fuse A In AC AC nominal current of the A TABLE 29. S inverter ABBREVIATIONS AND ACRONYM ISC short circuit current A
Acronym Explanation ISC PV PV generator short-circuit A current
A Amperes ISC String short-circuit current of one string A
AC Alternating Current IST String current A
ASTM American Society for Testing kMMP MPP voltage factor -
and Materials LAC cable Simple line length of the AC m BAPV Building Applied Photovoltaics connect
BIPV Building Integrated Lm Simple wiring length m
PhotoVoltaics Lmin minimum distance between PV m BOS Balance Of System and obstacle
CEN – Committee for Standardization Lopti optimum distance between PV m European rows
DC Direct Current Ls distance Earth to sun km DIF Diffuse Irradiance n Number of strings of the PV - DIN Direct Normal Irradiance generator
DOD Depth of Discharge nPV module’s efficiency ΕPBT Energy Pay-Back Time P consumer power W
FIT Feed-In-Tariff PAC c able cable loss
IEC International Electrotechnical PINV DC DC power rating of the inverter W Commision PΝ maximum power point W Impp Current at maximum power P PV array power rating W point PV PR Performance Ratio % IRR Internal Rate of Return Q minimum battery capacity Ah ISO International Organisation for required Standardization T voltage temperature coefficient V/oC kWh Kilo-Watt-hour C T Minimum expected module oC LCA Life Cycle Analysis min temperature LED Light-Emitting Diode o Tmax Maximum expected module C MPP Maximum Power Point o temperature 25 C PPE Personal Protective Equipment o Tstc Module’s temperature at STC (25 C PR Performance Ratio oC) PSH Peak Sun Hours Vmax(INV) maximum input voltage of the V PV Photovoltaic inverter STC Standard Test Conditions VMPP(INV- minimum input voltage of the V UL Underwriter Laboratories Inc min) inverter at the MPP Standards o V(MPP -T) VMPP at different temperature C V Volts VMMP-STC MPP-voltage of the PV array at V STC
VOC open circuit voltage V ii. Symbols and Units VOC-STC open circuit voltage at STC V Voc-Tmin maximum open circuit voltage of V TABLE 30. 2 the array at irradiance 1kW/m SIMBOLS AND UNITS and Tmin Symbol Explanation Units Voc-Tmax maximum open circuit voltage of V 2 2 A DC cable cross section of the DC cable mm the array at irradiance 1kW/m
CINV inverter sizing factor % and T max d diameter of the obstacle m WPV peak wattage of the array
ds diameter of sun km ΔV voltage drop V o Ε daily energy requirement, Wh Wh φ latitude o FF filling factor % β Optimum Tilt G average daily number of PSH h κ electrical conductivity, m/Ω 2 H height of an obstacle m mm Ν loss factor % Iz cable current rating of the cable A
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Standard Test Method for PV Modules in ASTM Cyclic Temperature and Humidity E1171 iii. International and EU standards Environments Standard Test Methods for Insulation ASTM Integrity and Ground Path Continuity of PV with relevance to PVs E1462 Modules TABLE 31. ASTM Test Methods for Solar Radiation STANDARS IN TEST METHODS AND REFERENCE CELLS (Source: E1596 Weathering of PV Modules wwwpvresourcescom, 2011) Standard Test Method for Saltwater ASTM Pressure Immersion and Temperature Test methods and reference cells E1597 Testing of PV Modules for Marine Standard Test Method for Determination Environments of the Spectral Mismatch Parameter ASTM E973 ASTM Standard Practice for Visual Inspections of Between a PV Device and a PV Reference E1799 PV Modules Cell ASTM Standard Test Methods for Wet Insulation Test Methods for Measuring Spectral ASTM E1021 E1802 Integrity Testing of PV Modules Response of PV Cells ASTM Standard Test Methods for Determining Standard Specification for Physical E1830-09 Mechanical Integrity of PV Modules ASTM E1040 Characteristics of Nonconcentrator ASTM Standard Test Method for Wet Insulation Terrestrial PV Reference Cells E2047 Integrity Testing of PV Arrays Standard Test Method for Determining Standard Test Methods for Measurement of ASTM E1143 the Linearity of a PV Device Parameter ASTM Electrical Performance and Spectral with Respect To a Test Parameter E2236 Response of Nonconcentrator Multijunction Standard Test Method for Calibration of PV Cells and Modules ASTM E1125 Primary Non-Concentrator Terrestrial PV ASTM Standard Test Method for Hot Spot Reference Cells Using a Tabular Spectrum E2481 Protection Testing of PV Modules Standard for Flat-Plate PV Modules and UL 1703 Panels TABLE 32. STANDARS IN SOLAR MODULES (Source: wwwpvresourcescom, wwwepiaorg, 2011) TABLE 33. Solar Modules STANDARS IN GRID-CONNECTED PV SYSTEMS (Source: wwwpvresourcescom, 2011) Datasheet and nameplate information of PV EN 50380 module Grid-Connected PV Systems Crystalline silicon terrestrial PV (PV) Electrical installations of buildings – Part 7- IEC 61215 modules - Design qualification and type IEC 60364- 712: Requirements for special installations approval 7-712 or locations – Solar PV (PV) power supply Terrestrial PV power generating systems - IEC 61277 systems General and guide PV (PV) systems – Characteristics of the IEC 61727 PV devices – Procedures for temperature utility interface IEC and irradiance corrections to measured I-V PV systems – Power conditioners – IEC 61683 60891:2009 characteristics Procedure for measuring efficiency Balance-of-system components for PV IEC 60904 PV devices (principals for measurements) IEC 62093 systems – Design qualification natural Series environments IEC 61345 UV test for PV (PV) modules Test procedure of islanding prevention Thin-film terrestrial PV modules - Design IEC 61646 IEC 62116 measures for utility-interconnected PV qualification and type approval inverters IEC 61701 Salt mist corrosion testing of PV modules Grid connected PV systems – Minimum PV module safety qualification - Part 1: IEC 62446 requirements for system documentation, IEC 61730-1 Requirements for construction commissioning tests and inspection PV module safety qualification - Part 1: Electrical installations of buildings – IEC 61730-2 IEC 60364- Requirements for testing Requirements for special installations or 7-712 Crystalline silicon PV array - On-site locations – Solar PV power supply systems IEC 61829 measurement of I-V characteristics Concentrator PV modules and assemblies - IEC 62108 Design qualification and type approval TABLE 34. STANDARS IN OFF-CONNECTED PV SYSTEMS (Source: Recommended practice for qualification of IEEE 1513 wwwpvresourcescom, 2011) concentrator PV modules Standard Test Method for Determining ASTM Off-Grid PV Systems Resistance of PV Modules to Hail by Impact Characteristic parameters of stand-alone PV E1038 IEC 61194 with Propelled Ice Balls (PV) systems PVTRIN Training course- Solar installers handbook 183
Rating of direct coupled PV (PV) pumping Specific case of automotive flooded lead- IEC 61702 systems acid batteries available in developing IEC/PAS Specifications for the use of renewable countries 62011 energies in rural ecentralized electrification Recommendations for small renewable IEEE Std IEEE Recommended Practice for Testing the IEC/TS energy and hybrid systems for rural 1526 Performance of Stand-Alone PV Systems 62257-9-1 electrification – Part 9-1: Micropower PV Stand-Alone Systems – Design systems IEC 62124 Qualification and Type Approval Recommendations for small renewable IEC/TS energy and hybrid systems for rural Portable solar PV lanterns – blank detail 62257-9-2 specification Approval under the IEC system electrification – Part 9-2: Microgrids IEC PVRS11 for conformity testing and certification of Recommendations for small renewable electrical equipment (IECEE) IEC/TS energy and hybrid systems for rural Portable solar PV lanterns – design 62257-9-3 electrification – Part 9-3: Integrated system IEC qualification and type approval Amendment – User interface PVRS11A 1, extension to include lanterns with nickel- Recommendations for small renewable metal hydride batteries IEC/TS energy and hybrid systems for rural 62257-9-4 electrification – Part 9-4: Integrated system TABLE 35. S – User installation TANDARS IN RURAL ELECTRIFICATION (Source: Recommendations for small renewable wwwpvresourcescom, 2011) energy and hybrid systems for rural IEC/TS electrification – Part 9-5: Integrated system 62257-9-5 Rural Electrification – Selection of portable PV lanterns for rural Recommendations for small renewable electrification projects IEC/TS energy and hybrid systems for rural Recommendations for small renewable 62257-1 electrification – Part 1: General introduction energy and hybrid systems for rural IEC/TS to rural electrification electrification – Part 9-6: Integrated system 62257-9-6 Recommendations for small renewable – Selection of PV Individual Electrification IEC/TS energy and hybrid systems for rural Systems (PV-IES) 62257-2 electrification – Part 2: From requirements Recommendations for small renewable to a range of electrification systems energy and hybrid systems for rural Recommendations for small renewable IEC/TS electrification – Part 12-1: Selection of self- IEC/TS energy and hybrid systems for rural 62257-12-1 ballasted lamps (CFL) for rural electrification 62257-3 electrification – Part 3: Project development systems and recommendations for and management household lighting equipment Recommendations for small renewable Test Procedure of Islanding prevention IEC/TS energy and hybrid systems for rural IEC 62116 measures for utility –interconnected 62257-4 electrification – Part 4: System selection and inverters design Recommendations for small renewable IEC/TS energy and hybrid systems for rural TABLE 36. S 62257-5 electrification – Part 5: Protection against TANDARS IN MONITORING (Source: wwwpvresourcescom, electrical hazards 2011) Recommendations for small renewable Monitoring IEC/TS energy and hybrid systems for rural PV system performance monitoring – 62257-6 electrification – Part 6: Acceptance, IEC 61724 Guidelines for measurement, data exchange operation, maintenance and replacement and analysis Recommendations for small renewable IEC/TS Communication networks and systems for energy and hybrid systems for rural 62257-7 power utility automation – Part 7-420: Basic electrification – Part 7: Generators IEC 61850-7 communication structure – Distributed Recommendations for small renewable energy resources logical nodes IEC/TS energy and hybrid systems for rural IEC 60870 Telecontrol equipment and systems 62257-7-1 electrification – Part 7-1: Generators – PV
arrays Recommendations for small renewable TABLE 37. energy and hybrid systems for rural IEC/TS STANDARS IN INVERTERS (Source: wwwpvresourcescom, electrification – Part 7-3: Generator set – 62257-7-3 wwwepiaorg, 2011) Selection of generator sets for rural electrification systems Recommendations for small renewable Inverters energy and hybrid systems for rural Datasheet and nameplate information of PV IEC/TS EN 50524 electrification – Part 8-1: Selection of inverters 62257-8-1 Safety of power converters for use in PV batteries and battery management systems IEC 62109-1 for stand-alone electrification systems – power systems – Part 1: General PVTRIN Training course- Solar installers handbook 184
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requirements corrosion resisting steels for general Safety of power converters for use in PV purposes IEC 62109-2 power systems – Part 2: Particular Stainless steels - Part 3: Technical delivery requirements for inverters conditions for semi-finished products, bars, PV systems – Power conditioners – EN 10088-3 rods, wire, sections and bright products of IEC 61683 Procedure for measuring efficiency corrosion resisting steels for general Standard for Inverters, Converters, and purposes UL 1741 Controllers for Use in Independent Power Designation systems for steels - Part 1: Steel EN 10027-1 Systems names Overall efficiency of grid connected PV Designation systems for steels - Part 2: EN 50530 EN 10027-2 inverters Numerical system
TABLE 41. TABLE 38. STANDARSS IN JUNCTION BOXES (Source: wwwpvresourcescom, TANDARS IN CHARGE CONTROLLERS (Source: 2011) wwwpvresourcescom, wwwepiaorg, 2011) Junction Boxes Charge Controllers DIN V VDE Junction Boxes for PVs Battery charge controllers for PV systems - 0126-5 IEC 62509 Performance and functioning EN 50548 Junction Boxes for PVs Balance-of-system components for PV IEC 62093 systems - Design qualification natural TABLE 42. environments STANDARS IN Wires/Cables (Source: wwwepiaorg, 2011) Wires/Cables TABLE 39. ULS -SU 4703 PV wire TANDARS IN BATTERIES UL 854 Service Entrance Cables TUV Rheinland Requirements for cables for PV systems Batteries 2Pfg1169 Secondary cells and batteries for solar PV IEC 61427 energy systems - General requirements and methods of test TABLE 43. Recommended practice for installation and STANDARS IN CONNECTORS Source: wwwepiaorg, 2011 IEEE Std maintenance of lead-acid batteries for PV 937 Connectors systems Connectors for PV systems-Safety EN 50521 IEEE Std Recommended Practice for Sizing Lead-Acid requirements and tests 1013 Batteries for PV (PV) Systems UL-SU 6703 Connectors for use in PV systems Recommended practice for determining IEEE Std UL 486A/486B Wire Connectors performance characteristics and suitability 1361 of batteries in PV systems TABLE 44. OTHER BOS STANDARDS (Source: wwwpvresourcescom, 2011) TABLE 40. STANDARDS RELATED TO MOUNTING STRUCTURES (Source: Other BOS standards wwwpvresourcescom, 2011) Overvoltage protection for PV (PV) power IEC 61173 generating systems - Guide Standards related to mounting structures
Eurocode 1: Actions on structures - Part 1-2: EN 1991-1- General actions - Actions on structures TABLE 45. 2 exposed to fire STANDARDS IN GLASS AND ITS APPLICATIONS IN BUILDINGS EN 1991-1- Eurocode 1 - Actions on structures - Part 1- AND CLOSELY REFER ALSO TO BIPV SYSTEMS (Source: 3 3: General actions - Snow loads wwwpvresourcescom, 2011) EN 1991-1- Eurocode 1: Actions on structures - Part 1-4: 4 General actions - Wind actions Glass and its applications in buildings and closely refer also to BIPV systems Aluminium and aluminium alloys - Chemical Glass in building - Determination of EN 573-1 composition and form of wrought products - EN 410 Part 1: Numerical designation system luminous and solar characteristics of glazing Hot dip galvanized coatings on fabricated Glass in building - Security glazing - Testing ISO 1461 iron and steel articles - Specifications and EN 356 and classification of resistance against test methods manual attack Stainless steels - Part 1: List of stainless Glass in building - Determination of thermal EN 10088-1 steels EN 673 transmittance (U value) - Calculation method Stainless steels - Part 2: Technical delivery EN 10088-2 conditions for sheet/plate and strip of EN 572-1 Glass in building - Basic soda lime silicate PVTRIN Training course- Solar installers handbook 185
glass products - Part 1: Definitions and safety glass general physical and mechanical properties Glass in building -- Laminated glass and ISO 12543- Glass in Building - Basic soda lime slicate laminated safety glass -- Part 3: Laminated EN 572-2 3 glass products - Part 2: Float glass glass Glass in Building - Basic soda lime silicate Glass in building -- Laminated glass and EN 572-5 ISO 12543- glass products - Part 5: Patterned glass laminated safety glass -- Part 4: Test 4 Glass in building - Basic soda lime silicate methods for durability EN 572-8 glass products - Part 8: Supplied and final Glass in building -- Laminated glass and ISO 12543- cut sizes laminated safety glass -- Part 5: Dimensions 5 Glass in building - Basic soda lime silicate and edge finishing EN 572-9 glass products - Part 9: Evaluation of ISO 12543- Glass in building -- Laminated glass and conformity/Product standard 6 laminated safety glass -- Part 6: Appearance Glass in building - Special basic products - ASTM Standard Specification for Laminated EN 1748-1- Borosilicate glasses - Part 1-1: Definition and C1172 Architectural Flat Glass 1 general physical and mechanical properties ASTM Standard Test Method for Security Glazing Glass in building - Special basic products - F1233 Materials And Systems EN 1748-2- Glass ceramics - Part 2-1 Definitions and 1 general physical and mechanical properties Glass in building - Special basic products - A database that the PV related standards can EN 1748-1- Borosilicate glasses - Part 1-2: Evaluation of 2 be downloaded is BSI (British Standards conformity/Product standard Glass in building - Special basic products - Institute) Online. All standards can also be EN 1748-2- Glass ceramics - Part 2-2: Evaluation of 2 purchased through the webstores of the conformity/Product standard different standardization organisation (ISO, Glass in building - Thermally toughened EN 13024-1 borosilicate safety glass - Part 1: Definition IEC, ASTM etc). and description Glass in building - Thermally toughened EN 13024-2 borosilicate safety glass - Part 2: Evaluation of conformity/Product standard iv. National standardisation Glass in building - Pendulum test - Impact EN 12600 test method and classification for flat glass organizations Glass in building - Determination of the EN 1288-1 bending strength of glass - Part 1: Fundamentals of testing glass Glass in building - Determination of bending TABLE 46. strength of glass - Part 2: Coaxial double ring NATIONAL STANDARDISATION ORGANISATIONS EN 1288-2 test on flat specimens with large test Standardisation Link Country surface areas Organisation Glass in building - Determination of the Belgium Institut belge de wwwibnbe bending strength of glass - Part 3: Test with EN 1288-3 normalisation (IBN) specimen supported at two points (four The Bulgarian Institute http://wwwbds- Bulgaria point bending) for Standardisation bgorg Glass in building - Determination of the Croatian Standards wwwhznhr Croatia EN 1288-4 bending strength of glass - Part 4: Testing of Institute channel shaped glass Cyprus Organisation wwwcysorgcy Cyprus Glass in building - Determination of the for Standardisation bending strength of glass - Part 5: Coaxial EN 1288-5 Hellenic Organization http://wwwelotgr double ring test on flat specimens with Greece for Standardization /defaultaspx small test surface areas (ELOT) Glass in building - Laminated glass and Asociacion Espanola http://wwwaenor EN 14449 laminated safety glass - Evaluation of Spain de Normalizacion y es conformity/Product standard Certificacion (AENOR) ISO 3585 Borosilicate glass 33 -- Properties Asociatia de http://wwwasror Glass in building -- Basic soda lime silicate ISO 16293- Romania Standardizare din o/engleza2005/de glass products -- Part 1: Definitions and 1 România (ASRO) fault_e nghtml general physical and mechanical properties British Standards http://wwwbsigro Glass in building -- Laminated glass and United Kingdom ISO 12543- Institution (BSI) upcom laminated safety glass -- Part 1: Definitions 1 and description of component parts ISO 12543- Glass in building -- Laminated glass and 2 laminated safety glass -- Part 2: Laminated PVTRIN Training course- Solar installers handbook 186
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Circuit breaker v. Graphical Symbols
IEC 60617 contains graphical symbols for use Make contact normally in electrotechnical diagrams. The database is open, also general symbol for a switch the official source of IEC 60617 including more than1750 symbols. Conductor, group of conductors, line, cable, Some of the most commonly met are circuit, transmission path presented in the table below. Three conductors TABLE 47. G
RAPHICAL SYMBOLS (Source: Colin H Simmons, Dennis E Conductors in a cable, Maguire, Manual of engineering drawing, 2004) three conductors
Links Description shown Earth or ground, Direct current general symbol
Alternating current Ammeter
Positive polarity Voltmeter Negative polarity
Propagation, energy flow, Contactor, normally open signal flow, one way Junction of conductors Contactor, normally closed
Double junction of Operating device (relay conductors coil), general symbol
Primary cell or accumulator Wattmeter Inductor, coil, winding, choke Semiconductor diode, Machine, general symbol general symbol The asterisk is replaced by a letter designation as follows: Tunnel diode C synchronous converter G generator Resistor, general symbol
GS synchronous generator M motor Watt-hour meter MG machine capable of use as a generator or motor MS synchronous motor Signal lamp, general symbol Battery of accumulators or primary cells Photovoltaic cell Fuse, general symbol
Fuse with the supply side indicated
Connecting link, closed
Connecting link, open
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vi. Characteristic I-V curves for modules
FIGURE 132.FIGURE 137. C HARACTERISTIC I-V CURVES FOR MODULES (Source:wwwenergygridsolutionscom/solar-sharphtml, October 2011)
viii. Useful links
Links Description Information on solar power and its applications large wwwpvresourcescom scale PV power plants database on reports simulation tools Data on best practices, urban wwwpvdatabaseorg PV projects, BIPV products National reports and vii. Radiation maps wwwiea-pvpsorg statistiics on PV market FIGURE 133.FIGURE 138. E Detailed information on the UROPE RADIATION MAPS (Source: administrative processes http://rejrceceuropaeu/pvgis/, October 2011) that need to be followed in wwwpvlegaleu order to install a PV system in each of the participating countries Information on production equipment, solar http://wwwenfcn/datab components (eg inverters, ase/panelshtml batteries), solar materials, solar panels, sellers, solar system installers http://wwwposharpcom Extensive database with /photovoltaic/databasea characteristics of many PV spx panels Database of all commercially available solar panels with http://pvbincom functionality to search and sort by different data parameters http://wwwnrelgov/pv/ performance_reliability/ Information about failures failure_databasehtml observed in PV installations
database including over 750 http://wwwsemiorg/en/ PV facilities and covering the Store/Marketinformatio PVindustry value chain from n/photovoltaics/CTR_02 FIGURE 134.FIGURE 139. Poly-Si to module 8755 RADIATION MAPS (Source: http://mapperycom, October 2011) manufactures Resource for PVTRIN Training course- Solar installers handbook 188
ANNEXES
key business and technical contacts Climatological database for solar energy applications: a meteorological database wwwmeteonormcom containing comprehensive climatological data for solar engineering applications at all points of the globe The model algorithm estimates beam, diffuse and reflected components of the clear-sky and real-sky global irradiance/irradiation on http://rejrceceuropaeu/ horizontal or inclined pvgis/ surfaces The total daily irradiation [Wh/m2] is computed by the integration of the irradiance values [W/m2] calculated at regular time intervals over the day IEC provides a platform to companies, industries and governments for meeting, wwwiecch discussing and developing the International Standards they require American Society for Testing and Materials international standards for materials, wwwastmorg products, systems and
services used in construction, manufacturing and transportation Committee for Standardization platform for wwwceneu the development of European Standards and other technical specifications Underwriter Laboratories Inc wwwulcom database with more than 1,000 Standards for Safety International Organisation for Standardization World wide federation of national wwwisoch standards institutes, promoting the development of standardization of goods and services Database of more than 50,000 standards rich in http://shopbsigroupcom business-critical content /Navigate-by/BSOL/ covering a broad range of disciplines for all industry sectors
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LIST OF TABLES TABLE 15. SUPPORTING MECHANISMS TO PV TABLE 1. TYPICAL TYPE AND SIZE OF INSTALLATION 53 APPLICATIONS PER MARKET SEGMENT FOR GRID- CONNECTED PV SYSTEMS. (Source: Solar TABLE 16. APPLIANCES AND DAILY ENERGY Generation VI, EPIA and Greenpeace) 9 REQUIREMENTS 54 TABLE 2. OPTIMUM TILT FOR THE PV PANEL TABLE 17. PV -MODULE’S CHARACTERISTICS55 (NORTH HEMISPHERE) (Source : Markvart & TABLE 18. INVERTER’S CHARACTERISTICS 56 Castafier, 2003) 19 TABLE 19. PROBLEMS AND SOLUTIONS AT TABLE 3. VALUES OF TYPICAL ENERGY INSTALLATION OF PV MODULES ON PITCHED CONSUMPTION (Source: Markvart & Castafier, ROOFS . (Source: SEC) 66 2003) 22 TABLE 20. FACTOR OF ORIENTATION AND TABLE 4. APPLIANCE CLASSES. (Source: IEC, TILT (Source:SEC ) 77 2011) 31 TABLE 21. PLANNING WORK AT HEIGHT TABLE 5. PENETRATION DEPTH BY (Source: OHSA, 2011) 92 LIGHTNING PROTECTION CLASS ACCORDING TO VDE 0185-305. (Source: OBO-Betterman, 2010) 32 TABLE 22. ELECTRICAL FEATURES (Source: Tknika, 2004) 104 TABLE 6. INDICATIVE VALUES (Source: Antony, 2007) 33 TABLE 23. SCHEDULE OF TEST RESULTS. (Source: DTI, 2006) 125 TABLE 7. PV SIMULATION TOOLS 38 TABLE 24. TEST METHOD TABLE (Source: DTI, TABLE 8. SHARES IN THE TOTAL SYSTEM 2006) 126 PRICE (Source: EPIA 2011) 42 TABLE 25. COMMISSIONING TEST SHEET TABLE 9. LIFECYCLE GREENHOUSE GAS (Source: DTI, 2006) 127 EMISSION ESTIMATES FOR ELECTRICITY GENERATORS. (Source: Moskowitz & Fthenakis, TABLE 26. PV COMMISSIONING TEST SHEET. 1991). 45 Source: BRE et al, 2006) 129 TABLE 10. ON MASS BASIS FRACTIONS OF A TABLE 27. TYPICAL FAILURES AND PV MODULE (Source: Moskowitz & Fthenakis, CORRECTIVE MEASURES AND TROUBLESHOOTING 1991) 46 (Source: J N Karamchetti, Maintenance of Solar Photovoltaic & Renewable Energy Installations)163 TABLE 11. STANDARDS FOR BOS (Source: PVResources, 2011) 47 TABLE 28. MAINTENANCE CHECKLIST (Source: http://wwwcontractorsinstitutecom/) 165 TABLE 12. PPRICES FOR ENERGY PRODUCED BY PV 48 TABLE 29. SABBREVIATIONS AND ACRONYM182 TABLE 13. PV DATABASES 50 TABLE 30. SIMBOLS AND UNITS 182 TABLE 14. ADMINISTRATIVE ISSUES 51
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TABLE 31. STANDARS IN TEST METHODS AND REFERENCE CELLS (Source: wwwpvresourcescom, 2011) 183 TABLE 32. STANDARS IN SOLAR MODULES (Source: wwwpvresourcescom, wwwepiaorg, 2011) 183 TABLE 33. STANDARS IN GRID-CONNECTED PV SYSTEMS (Source: wwwpvresourcescom, 2011)183 TABLE 34. STANDARS IN OFF-CONNECTED PV SYSTEMS (Source: wwwpvresourcescom, 2011)183 TABLE 35. STANDARS IN RURAL ELECTRIFICATION (Source: wwwpvresourcescom, 2011) 184 TABLE 36. STANDARS IN MONITORING (Source: wwwpvresourcescom, 2011) 184 TABLE 37. STANDARS IN INVERTERS (Source: wwwpvresourcescom, wwwepiaorg, 2011) 184 TABLE 38. STANDARS IN CHARGE CONTROLLERS (Source: wwwpvresourcescom, wwwepiaorg, 2011) 185 TABLE 39. STANDARS IN BATTERIES 185 TABLE 40. STANDARDS RELATED TO MOUNTING STRUCTURES (Source: wwwpvresourcescom, 2011) 185 TABLE 41. STANDARS IN JUNCTION BOXES (Source: wwwpvresourcescom, 2011) 185 TABLE 42. STANDARS IN Wires/Cables (Source: wwwepiaorg, 2011) 185 TABLE 43. STANDARS IN CONNECTORS Source: wwwepiaorg, 2011 185 TABLE 44. OTHER BOS STANDARDS (Source: wwwpvresourcescom, 2011) 185 TABLE 45. STANDARDS IN GLASS AND ITS APPLICATIONS IN BUILDINGS AND CLOSELY REFER ALSO TO BIPV SYSTEMS (Source: wwwpvresourcescom, 2011) 185 TABLE 46. NATIONAL STANDARDISATION ORGANISATIONS 186 TABLE 47. GRAPHICAL SYMBOLS (Source: Colin H Simmons, Dennis E Maguire, Manual of engineering drawing, 2004) 187
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LIST OF FIGURES FIGURE 15. PV PANELS FOR SUN SCREENING. FIGURE 1. EXAMPLE OF THE PHOTOVOLTAIC (Source: ReSEL, TUC, 2010) 19 EFFECT. (Source: EPIA) 2 FIGURE 16. PV MODULES IN INCLINED ROOF FIGURE 2. TYPES OF SOLAR IRRADIANCE. (Source: Flickr, Sun Switch, 2011) 20 (Source: Tknika, 2004) 3 FIGURE 17. PANELS MOUNTED ABOVE ROOF FIGURE 3. SOLAR IRRADIATION AROUND THE (Source: Flickr, Entersolar, 2011) 20 WORLD. (Source: Gregor Czisch, ISET, Kassel, Germany) 3 FIGURE 18. GROUND MOUNTED PV PANELS IN CRETE (Source: ReSEL, TUC) 21 FIGURE 4. PV MODEULE CELL’S CONNECVTION. (Source: Tknika,2004) 4 FIGURE 19. TRACKING SYSTEM (Source: ReSEL, TUC) 21 FIGURE 5. DIFFERENT CONFIGURATION OF SOLAR POWER SYSTEMS. (Source: DTI,,2006) 4 FIGURE 20. I-V CURVE OF A SOLAR CELL 23 FIGURE 6. DIFFERENT CONFIGURATION OF FIGURE 21. EFFECT OF TEMPERATURE ON I-V SOLAR POWER SYSTEMS. (Source: EPIA) 5 CURVE 23 FIGURE 7. OVERVIEW OF EFFICIENCY OF PV FIGURE 22. SERIES CONNECTION 24 TECHNOLOGIES. (Source: EPIA 2011, Photon FIGURE 23. PARALLEL CONNECTION 24 International, February 2011, EPIA analysis) 8 FIGURE 24. SERIES AND PARALLEL FIGURE 8. STEPS TO BE FOLLOWED DURING CONNECTION 24 ON SITE VISIT 14 FIGURE 25. PV MODULES CONNECTED TO FIGURE 9. SOLAR RADIATION IN EUROPE. INVERTER USING CENTRAL INVERTER 25 (Source: PVGIS (http://re.jrc.ec.europa.eu/ pvgis/ 2011) 15 FIGURE 26. PV MODULES CONNECTED TO INVERTERS USING MODULE INVERTER 25 FIGURE 10. SHADING FROM NEIGHBORING OBSTACLES. (Source: Energia e Domotica, Flickr, FIGURE 27. PV MODULES CONNECTED TO 2011). 17 INVERTERS USING STRING INVERTER 26 FIGURE 11. MINIMUM DISTANCE OF PVS NOT FIGURE 28. EXAMPLES OF PROTECTION TO BE SHADED BY OBSTACLES 17 (Source: IEA PVPS, 2003)
FIGURE 12. Lmin, BASED ON THE THICKNESS OF THE OBJECT 17 FIGURE 13. MINIMUM DISTANCE BETWEEN ARROWS 18 FIGURE 14. ALTERNATIVES FOR INTEGRATING PVs IN BUILDINGS (Source: PURE project. Roman et al, 2008) 19
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LIST OF FIGURES
FIGURE 43. PV MODULE PRICE EXPERIENCE CURVE (US$/Wp & MW) (Source: EPIA, 2011) 42 FIGURE 44. ESTIMATING THE COST OF PV SYSTEMS 44 FIGURE 45. PV ENERGY PAYBACK TIMES OF PV TECHNOLOGIES (Source: Fthenakis & Alsema, 2006) 45 FIGURE 46. STANDARDS FOR PV SYSTEMS INSTALLATION (Source: PVResources, 2011) 47 FIGURE 47. FBAPV ON FALT ROOF. (Source: SEC ) 62 FIGURE 48. BAPV ON PITCHED ROOF. 30 (Source:SEC ) 62 FIGURE 29. SMALL PV IN LIGHTNING SYSTEM FIGURE 49. BIPV ON ROOF. (Source: SEC ) 62 MESH. (Source: Schletter Solar, 2005). 31 FIGURE 50. ALTERNATIVES FOR INTEGRATING FIGURE 30. LARGE PV SYSTEM ON ROOF. PVs IN BUILDINGS (Source: SST) 63 (Source: Schletter Solar, 2005). 31 FIGURE 51. OPTIONS FOR INTEGRATION OF PV FIGURE 31. ROLLING SPHERE METHOD. ( SYSTEMS ON FLAT ROOFS (Source: ECN). 64 Source: OBO-Betterman, 2010) 32 FIGURE 52. FPV INSTALLATION ON FLAT ROOF FIGURE 32. CHARGE CONTROLLER SET POINTS – EXTERNAL VIEW AND STRUCTURE. (Source: SEC )65 (Source: Dunlop, 1997) 35 FIGURE 53. OPTIONS FOR INTEGRATION OF PV FIGURE 33. SHUNT CHARGE CONTROLLER SYSTEMS ON PITCHED ROOFS (Source: ECN). 65 (Source: DGS LV, 2008) 35 FIGURE 54. BIPV ON RESIDENTILA BUILDING FIGURE 34. SERIES CHARGE CONTROLLER (Source:SEC) 66 (Source: DGS LV, 2008) 36 FIGURE 55. OPTIONS FOR INTEGRATION OF PV FIGURE 35. DESIGN OF AN AUTONOMOUS SYSTEMS ON FLAT ROOFS (Source: Education and SYSTEM 37 training material for architects, (ECN). 67 FIGURE 36. DESIGN OF A GRID CONNECTED FIGURE 56. FBAPV ON REFURBISHED SYSTEM 37 RESIDENTILA BUILDING (Source:SEC) 68 FIGURE 37. ON LINE PV*SOL TOOL 39 FIGURE 57. BIPV IN WARM FACADE (Source:SST) 68 FIGURE 38. INPUT DATA EXAMPLE ON DEMO VERSION OF PV F-CHART 39 FIGURE 58. BIPV IN WARM FACADE (Source: SST, 2008) 69 FIGURE 39. OUTPUT OF EXAMPLE ON DEMO VERSION OF PV F-CHART (BASED IN FIGURE 38) 39 FIGURE 59. BIPV IN COLD FACADE (Source: SST) 70 FIGURE 40. EXAMPLE FOR ATHENS ON DEMO VERSION NSOL. 40 FIGURE 60. OPTIONS FOR INTEGRATION OF PV SYSTEMS ON GLASS ROOFS (Source: ECN). 71 FIGURE 41. ON LINE TOOL FROM THE AUSTRALIAN NATIONAL UNIVERSITY 41 FIGURE 61. OPTIONS FOR INTEGRATION OF PV SYSTEMS ON PARASOL (Source: ECN). 72 FIGURE 42. BIPV VISUALIZATION ON EXISTING BULDING IN CHANIA USING ECOTECT (Source: FIGURE 62. EXAMPLE OF GLASS ROOF WITH Papantoniou and Tsoutsos, 2008) 41 PV MODULES (Source:SEC) 72 PVTRIN Training course- Solar installers handbook 193
FIGURE 63. OPTIONS FOR INTEGRATION OF PV FIGURE 84. ATTACHING PV MODULES TO THE SYSTEMS IN SHADING DEVICES (Source: ECN). 73 STRUCTURE. (Source: EKILOR) 105 FIGURE 64. PV SHADING (Source:ECN) 73 FIGURE 85. ATTACHING PV MODULES TO THE STRUCTURE. (SOURCE: EKILOR) 105 FIGURE 65. INSTALLATION OF PV MOVABLE SHADING ELEMENT (Source:SST) 73 FIGURE 86. SOLAR INVERTER. (Source: Saecsa energia solar, 2011) 108 FIGURE 66. COMBINED PV-SOLAR TERMAL FUNCTION (Source:ECN) 74 FIGURE 87. DIFFERENT AVAILABILITY OPTIONS. (Source: Tknika, 2004) 111 FIGURE 67. ROOF OF BUS STOP AND CYCLE PARK WITH PV MODULES (Source:SEC) 75 FIGURE 88. PARALLEL AND CROSSED PARALLEL CONNECTIONS. (Source:Tknika) 111 FIGURE 68. PLANNING SOLUTION FOR ONE SITE. 76 FIGURE 89. 48 V. 100 Ah. SERIES CONNECTION. 4 BATTERIES. (Source: Tknika, FIGURE 69. SHADING FROM TREES 2004) 112 (Source:ECN) 78 FIGURE 90. 24 V. 100 Ah. SERIAL FIGURE 70. SELF-SHADING (Source:ECN) 78 CONNECTION. 2 BATTERIES. (Source:Tknika) 112 FIGURE 71. DON’T WALK ON PV MODULES FIGURE 91. 4V. 200Ah. MIXED CONNECTION. 2 (Source:ECN) 79 GROUPS OF 2 SERIAL BATTERIES PARALLEL FIGURE 72. DPV ON ROOF (Source:ECN) 80 CONNECTED. (Source: Tknika) 112 FIGURE 73. INTEGRATION OF PV MODULES IN FIGURE 92. LOCATION OF THE CURRENT / EXISTING BUILDING (Source: SEC ) 80 VOLTAGE BATTERY IN A PHOTOVOLTAIC INSTALLATION. (Source: Tknika,2004) 114 FIGURE 74. WATER DISTRICT NEW LAND (Source: SEC ) 80 FIGURE 93. SOLAR REGULATOR. (Source: Solostocks, 2011) 114 FIGURE 75. RESIDENTIAL AREA AMERSFOORT (Source: SEC ) 81 FIGURE 94. DDETAILS OF PV REGULATOR CONNECTIONS. (Source:Tknika) 115 FIGURE 76. PV MODULES ON THE FLOATING ISLANDS ON THE LAKE TITICACA (Source: SEC ) 82 FIGURE 95. PHOTOVOLTAIC FIGURE. (Source: TKNIKA) 117 FIGURE 77. ARC FLASH HAZARD (Source: OSEIA,2011 ) 91 FIGURE 96. DIFFERENT POSSIBILITIES (Source: Tknika, 2004) 118 FIGURE 78. CURRENT CLAP (Source: OSEIA,2011) 91 FIGURE 97. MONITORING THE ALTITUDE OF THE SUN (Source: Tknika, 2004) 118 FIGURE 79. MOBILE TOWER(Source: OHSA, 2011) 93 FIGURE 98. MONITORING THE SOLAR AZIMUTH (Source: Tknika, 2004) 118 FIGURE 80. MOBILE ELEVATING WORK PLATFORM (Source: OHSA, 2011) 93 FIGURE 99. MONITORING FROM A SINGLE AXIS ANGLED NORTH-SOUTH. (Source: Tknika, FIGURE 81. LEANNING LADDER (Source: OHSA, 2004) 118 2011) 94 FIGURE 100. DUAL AXIS MONITORING. A) FIGURE 82. ARRAY FRAME EARTHING (Source: Tknika, 2004) 119 DECISION TREE (Source: BRE et al, 2006). 101 FIGURE 101. Dual axis monitoring. (Source: FIGURE 83. UNION OF PHOTOVOLTAIC Tknika, 2004) 119 MODULES ( Source: Flickr, 2011) 105 FIGURE 102. POINTS OF SUPPORT (Source: Tknika, 2004) 119 PVTRIN Training course- Solar installers handbook 194
LIST OF FIGURES
FIGURE 103. ELEMENTS OF ANCHORAGE FIGURE 124. EXAMPLE OF SHADINGS AT THE (Source: Tknika, 2004) 120 LOCATION 153 FIGURE 104. GRID-CONNECTED INSTALLATION FIGURE 125. FSIMUATION RESULTS - (Source: Tknika, 2004) 121 PRODUCTION OF ELECTRICITY 154 FIGURE 105. GRID-CONNECTED INSTALLATION FIGURE 126. KEEPING RECORDS FOR UNIFILAR DIAGRAM (Source: Tknika, 2004) 121 ELECTRICITY PRODUCTION FROM PV GRIT CONNECTED SYSTEM, CYPRUS. (Source: Cyprus FIGURE 106. A BLOCK DIVISION OF GRID Energy Agency) 158 CONNECTED INSTALLATION (Source: Tknika, 2004)122 FIGURE 127. PERIODICAL INSPECTION PV GRIT FIGURE 107. STAND-ALONE PV SYSTEM ( CONNECTED ROOF SYSTEM, CYPRUS. (Source: Source: TKNIKA) 123 Johnsun Heaters Ltd, Cyprus) 159 FIGURE 108. AURINKOLAHTI SCHOOL. (Source: FIGURE 128. BATTERY INSPECTION IN STAND- City of Helsinki) 135 ALONE PV SYSTEMS, CYPRUS. (Source: Cyprus FIGURE 109. DISPLAY OF PV SYSTEM. (Source: Energy Agency) 159 Kari Ahlqvist) 136 FIGURE 129. INSPECTION OF INVERTERS IN FIGURE 110. PVSYSTEM ON SCHOOL. (Source: GRIT CONNECTED ROOF PV SYSTEMS, CYPRUS. Kari Ahlqvist) 136 (Source: Cyprus Energy Agency) 160 FIGURE 111. PV SYSTEM ON ROOF. (Source: FIGURE 130. POSSIBLE SHADING FROM Kari Ahlqvist) 137 GROWING VEGETATION. (Source: Terza Solar Ltd)161 FIGURE 112. BERDEN SOLAR PLANT. (Source: FIGURE 131. ELECTRICAL CONNECTIONS www.plan-net.si) 138 MAINTENANCE. (Source: Terza Solar Ltd) 161 FIGURE 113. PV SYSTEM ON ROOF. (Source: FIGURE 132. CHARACTERISTIC I-V CURVES FOR BISOL Group d.o.o) 140 MODULES (Source:wwwenergygridsolutionscom/solar- FIGURE 114. ATHENS METRO MALL. 142 sharphtml, October 2011) 188 FIGURE 115. ATHENS METRO MALL. 143 FIGURE 133. EUROPE RADIATION MAPS FIGURE 116. LATOKARTANO SCHOOL. (Source: (Source: http://rejrceceuropaeu/pvgis/, October City of Helsinki) 144 2011) 188 FIGURE 117. BLACKPOOL CENTRE FOR FIGURE 134. RADIATION MAPS (Source: EXCELLENCE IN THE ENVIRONMENT. (Source: http://mapperycom, October 2011) 188 Blackpool City Council) 146 FIGURE 118. BLACKPOOL CENTRE FOR EXCELLENCE IN THE ENVIRONMENT. (Source: Halcrow Group ltd) 147 FIGURE 119. Orthophoto of building and suroundings 150 FIGURE 120. SOUTHERN TERRACE (view from NW) 151 FIGURE 121. SOLAR IRRADIATION AND AIR TEMPERATURE FOR SELECTED LOCATION 151 FIGURE 122. DISTANCE BETWEEN MODULES152 FIGURE 123. DISTIBUTION OF PV MODULES ON FLAT ROOF – MAXIMUM SIZE 152 PVTRIN Training course- Solar installers handbook 195
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