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5-Cells-Modules-And-Arrays.Pdf

5-Cells-Modules-And-Arrays.Pdf

Chapter 5

Cells, Modules and Arrays

Principles of Operation ● I-V Characteristics ● Response to Irradiance and Temperature ● Series/Parallel Connections ● Specifications and Ratings

 2012 Jim Dunlop Solar Overview

 Describing the photovoltaic (PV) effect and comparing the fabrication of solar cells from various manufacturing processes.

 Defining the current- (I-V) characteristic for a PV device and the key operating parameters.

 Understanding how , temperature and electrical load affect the output of a PV device.

 Determining the electrical output of similar and dissimilar PV devices connected in series and parallel.

 Explaining the purpose and operation of bypass .

 Describing the performance rating conditions and labeling requirements for PV modules.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 2 Cells, Modules and Arrays

Cell

Module

Array

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 3 Solar Cells

 Solar cells are devices that convert sunlight to DC .

(-) Electrical Load

Photovoltaic cell DC current flow

Phosphorous-doped -doped silicon (N-type) layer ~ 0.3 μm (P-type) < 250 μm (+)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 4 The

 The photovoltaic effect is the process of creating a voltage across charged materials that are exposed to electromagnetic radiation.

in sunlight impart their energy to excess charge carriers ( and holes) allowing them to freely move about the material.

 Charge opposition between the two materials creates an electrical field that provides momentum and direction to the free charge carriers, resulting in the flow of electrical current flow when the cell is connected to a load.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 5 Silicon Solar Cells

 Silicon solar cells produce about 0.5 to 0.6 volt independent of cell area, depending on temperature.  The current output of a depends primarily on the cell area, its efficiency, and the incident solar radiation.  Modern silicon solar cells are up to 8 inches in diameter and produce up to 4 and 8 amps under full sunlight.

Monocrystalline cell Polycrystalline cell

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 6 Wafer Production

 The following processes are commonly used to create P-type silicon wafers:

 The produces a single or monocrystalline wafer.

 The cast method produces a multigrain or polycrystalline wafer.

 The ribbon method produces polycrystalline wafers by drawing molten silicon between dies in a continuous process.

 Wafer are additionally processed to produce a complete solar cell.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 7 Moncrystalline Wafer Production: Czochralski Method

 Single crystal or wafers are grown in the form of a cylindrical ingot, creating a perfect crystal.

 A seed crystal is inserted into molten polysilicon doped with boron, rotated and drawn upward allowing the P-type silicon material to cool into a cylindrical ingot.

Czochralski Method

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 8 Wafer Production

 Polycrystalline or multi- crystalline silicon wafers are cast, forming a block-shaped ingot that has many crystals.

 Molten polysilicon doped with boron is poured into a rectangular crucible, and slowly cooled at controlled rate.

Cast Ingot Method  Polycrystalline wafers are also made using the ribbon method.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 9 Solar Cell Manufacturing

 Once a P-type silicon ingot is produced, a number of additional steps are required to create an actual solar cell.

Cropping Sawing

Phosphorous diffusion

Screen printing Electrical testing SolarWorld USA

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 10 Flat-Plate PV Modules

 Flat-plate PV modules respond to both direct and diffuse solar radiation, and are the smallest field installable generating unit.

SolarWorld Single (mono) crystalline Polycrystalline

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 11 Flat-Plate PV Modules

Polycrystalline Single (mono) crystalline 36 cell modules

60 cell polycrystalline module

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 12 Typical PV Module Construction

Continuous seal

Tempered glass EVA embedding

Solar cells Tough back sheet

High strength frame

SolarWorld USA

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 13 Emerging PV Module Technologies

 Thick wafer silicon P-N junction solar cells are considered first generation PV devices.

 Second generation devices are thin-film devices including:  (a-Si)  Telluride (CdTe)  Copper indium gallium selenide (CIS or CIGS)

 Other advanced PV module include:  Concentrating PV modules  AC modules  Polymer and organic solar cells

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 14 Thin-Film PV Modules

 Thin-film PV modules are produced by depositing ultra- thin layers of semiconductor materials on a flexible or rigid substrate.

 Thin-film modules have significant potential for cost and weight reductions.

 Disadvantages include lower efficiencies and higher degradation rates than crystalline silicon modules.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 15 Concentrating PV Modules

 Use to focus sunlight on solar cells up to 200-500 X.

 Employ advanced multijunction solar cells approaching efficiencies of up to 40%.

 Utilize only direct component of total global solar radiation, and employ two-axis sun tracking.

challenges include managing high temperatures and high DC currents. NREL, Bill Timmerman

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 16 AC Modules and Micro-Inverters

 Alternating-current (AC) modules are an integrated PV module and inverter product intended for installation as a single unit.

 AC modules do not have any field-installed DC wiring.

 Micro-inverters are separate module level inverters intended for field installation.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 17 Photovoltaic Arrays

 PV arrays are constructed from building blocks of individual PV modules, panels and subarrays that form a mechanically and electrically integrated DC power generation unit.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 18 Photovoltaic Arrays

Ground-mounted rack array

Pole-mounted tracking array

Standoff roof-mounted array

Building-integrated array  2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 19 Photovoltaic Arrays

Roof-mounted standoff array

Roof-mounted rack array

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 20 Leading Manufacturers of PV Cells and Modules

 BP Solar  Schott Solar

 JA Solar  SolarWorld

 Kyocera  SunPower

 Mitsubishi  Suntech

 Trina

 Q-Cells 

 Sanyo  2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 21 Current-Voltage (I-V) Characteristic

 The electrical performance of a PV device is given by it current- voltage (I-V) curve.

 Represents an infinite number of I-V operating points.

 Varies with solar radiation and device temperature.

Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 22 Key I-V Parameters

 PV device performance is specified by the following I-V parameters at a given temperature and Isc

condition: Pmp Imp  Open-circuit voltage (Voc)  Short-circuit current (Isc)  Maximum power point (Pmp) Area = Pmp  Maximum power voltage (Vmp)  Maximum power current (Imp)

Voltage (V) Vmp Voc

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 23 Power vs. Voltage Curve

Current vs. Voltage Power vs. Voltage Pmp Isc Imp

Pmp = Imp x Vmp

Voltage (V) Vmp Voc

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 24 PV Module Rating Conditions

 The electrical performance of PV modules is rated at Standard Test Conditions (STC):  Irradiance: 1,000 W/m2 , AM 1.5  Cell temperature: 25°C

Source: SolarWorld USA  2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 25 Fill Factor

 Fill factor (FF) is an indicator of the quality of a solar cell.

 FF = (Vmp x Imp) / (Voc x Isc) = Pmp / (Voc x Isc)

Isc Imp

Pmp = Imp x Vmp

Isc x Voc

Voltage (V) Vmp Voc  2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 26 Efficiency

P η = mp  Efficiency of a PV device is the EA× ratio of the electrical power where output and the solar irradiance η = efficiency input over the device area, P = maximum power rating (W) expressed as a percentage: mp = 2 E solar iradiance (W/m ) 2 A = surface area (m )

 P Example: η = mp  What is the efficiency for a PV EA× module that has a surface area of 200 W 2 η = 1.4 m , and produces 200 W (1000 W/m22 × 1.4 m ) maximum power when exposed to 1000 W/m2 solar irradiance? η =0.143 = 14.3%

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 27 Response to Electrical Load

 The electrical load connected to a PV device determines its operating point.  If a battery is connected to a PV device, the battery voltage sets the operating voltage for that PV device.  In a grid-connected PV system, the inverter loads the PV array at its maximum power point.

 From Ohm’s Law, the electrical load resistance that operates a PV device at its maximum power point is equal to Vmp/Imp (ohms).

+ Electrical PV Device Load -

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 28 Operating Point

Isc Imp

Pmp = Imp x Vmp

Voltage (V) Vmp Voc

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 29 PV Modules for Battery Charging

PV module maximum power voltage must be higher than battery voltage at highest operating temperature

Operating voltage range for 12-volt lead-acid battery: 11.5 to 14.5 volts.

Maximum power points

Module with 42 series-connected cells at 50°C (voltage is more than adequate for charging, but power is wasted)

Current(A) Module with 30 series-connected cells at 50°C (voltage too low to deliver maximum current to battery) Module with 36 series-connected cells operating at temperature of 50°C (optimal)

10 20 Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 30 Effect of Electrical Load on Operating Point

Decreasing

R = 0 resistance Increasing resistance

Load lines of constant resistance

Constant Temperature

R = ∞ Voltage

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 31 I-V Measurement Methods

Electrolytic capacitor

A

V

Variable Variable resistor battery PV Device

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 32 Solmetric PVA-600 PV Analyzer

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 33 Raydec DS-100 IV Curve Tracer

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 34 Spire 4600 SLP Flash Simulator

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 35 Response to Electrical Load: Example

 The maximum power voltage (Vmp) and maximum power current (Imp) for a PV module are 35.8 volts and 4.89 amps, respectively. What is the maximum power and load resistance required to operate at maximum power?

 The maximum power is calculated by the product of the maximum power voltage and maximum power current: 35.8 volts x 4.89 amps = 175 watts

 From Ohm’s Law, resistance is equal to the voltage divided by the current: 35.8 volts / 4.89 amps = 7.32 ohms

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 36 Solar Cell Equivalent Circuit

 A solar cell equivalent circuit consists of a current source in parallel with a and resistance, connected to a series resistance.

Series resistance

Current Diode source Shunt resistance Load resistance

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 37 Series Resistance

Low Rs Increasing Rs decreases Pmp, Vmp and Imp, and also reduces FF and Moderate Rs efficiency.

High Rs

Rs = - ∆V / ∆ I ∆I

∆V Voltage

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 38 Shunt Resistance

Decreasing Rsh decreases ∆I Pmp, Vmp and Imp.

∆V

Rsh = - ∆V / I

High Rsh Moderate Rsh Low Rsh

Voltage

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 39 Response to Solar Irradiance

Current increases with 1000 W/m2 increasing irradiance

750 W/m2

2 500 W/m Maximum power increases with increasing irradiance

250 W/m2 Maximum power voltage changes little with irradiance

Voc changes little with irradiance

Voltage Constant Temperature

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 40 Response to Solar Irradiance

Voc changes little with irradiance above 200 W/m2

Isc increases with increasing irradiance

0 200 400 600 800 1000

Irradiance (W/m2) Constant Temperature

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 41 Response to Solar Irradiance

 The power and current output of a PV device are proportional to the solar irradiance:

EIP 222= = EIP 111

 Example: A PV module produces 200 watts maximum power at 1000 W/m2. Assuming constant temperature, the maximum power output at an irradiance level of 600 W/m2 would be:

E2 600 PP21= ×= ×200 = 120 W E1 1000

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 42 Response to Temperature

 For crystalline silicon PV devices, increasing cell temperature results in a decrease in voltage and power, and a small increase in current.

Increasing temperature reduces power output Increasing temperature increases current

Increasing temperature reduces voltage

T = 0°C T = 25°C T = 50°C

Voltage  2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 43 Temperature-Rise Coefficient

 The temperature-rise coefficient relates the temperature of a given PV array to the ambient air temperature and solar irradiance:

TTcell=+× amb() C Trise− E where  Tcell = cell temperature ( C)  Tamb = ambient air temperature ( C)  2 C − = temperature-rise coefficient ( C/kW/m ) T rise  At peak sun, the difference between PV array and ambient air temperature can vary from 20 to 40°C, depending on the array mounting system design.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 44 Temperature Coefficients

 Temperature coefficients relate the effects of changing PV cell temperature on voltage, current and power.

 Percentage change coefficients are commonly used to translate voltage, current and power from one temperature condition to another temperature.

 For crystalline silicon PV, percentage change temperature coefficients are approximately:

 CV = -0.4%/°C (voltage decreases 1% for 2.5°C increase in temperature)

 CI = +0.04%/°C (current increases 1% for 25°C increase in temperature)

 CP = -0.45%/°C (power decreases 1% for 2.2°C increase in temperature)

 Since the temperature coefficient for current is an order of magnitude less than for voltage or power, the effects of temperature on current are not usually considered in systems design.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 45 Temperature Translation Equations

Vtrans= V ref +[ VCT ref ×× V ( cell − T ref )]

Ptrans= P ref +[ PCT ref ×× P ( cell − T ref )]

where

Vtrans = translated voltage at Tcell (V)

Vref = reference voltage at Tref (V)

Ptrans = translated power at Tcell (W)

Pref = reference power at Tref (W)  CV = voltage-temperature coefficient (% per C)  CP = power-temperature coefficient (% per C)  Tcell = cell temperature ( C)  Tref = reference temperature ( C)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 46 Response to Temperature: Example 1

 A 72-cell crystalline silicon PV module has a rated open-circuit voltage of 44.4 V at 25°C, and a voltage-temperature coefficient of -0.33 %/°C. What would the open-circuit voltage be at a cell temperature of 60°C?

Vtrans= V ref +[ VCT ref ×× V ( cell − T ref )]

V = 44.4 V + [44.4 V × -0.0033/ C × (60-25) C] trans V = 44.4 V - 5.19 V = 39.2 V trans  If the same PV module operates at -10°C (35°C lower than the reference temperature), the translated voltage is:

 Vtrans = 44.4 V + [44.4 V × -0.0033/ C × (-10 - 25) C]

Vtrans = 44.4 V + 5.19 V = 49.6 V

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 47 Response to Temperature: Example 2

 A crystalline silicon PV array has a power-temperature coefficient of -0.45 %/°C and rated maximum power output of 50 kW at 25°C and solar irradiance of 1000 W/m2. What would the array maximum power be at a cell temperature of 50°C?

Ptrans= P ref +[ PCT ref ×× P ( cell − T ref )]

P = 50 kW + [50 kW × -0.0045/ C × (50-25) C] trans P = 50 kW - 5.6 kW = 44.4 kW trans

 If the same PV module operates at 0°C (25°C lower than the reference temperature of 25°C), the translated power is:  Ptrans = 50 kW + [50 kW × -0.0045/ C × (0 - 25) C]

Ptrans = 50 kW + 5.6 kW = 55.6 kW

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 48 Building PV Arrays

 PV modules are connected electrically in series to build voltage output.

 Series strings of PV modules are connected in

parallel to build current and power output. Current (A)

Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 49 Monopole and Bipolar PV Arrays

 Monopole PV arrays consist of two output circuit conductors.

 Bipolar PV arrays combine two monopole arrays with a center tap.

Positive (+) Negative (-) Positive (+) Center Tap Negative (-)

PV Array PV Array PV Array

Monopole Array Bipolar Array

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 50 Connecting Similar PV Devices in Series

(+) 1 (-) (+) 2 (-) (+) n (-)

Vseries string = V1 + V2 ….. + Vn

Vseries string = V1 x n Pos (+) Neg (-) Iseries string = I1 = I2 ….. = In (for similar devices)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 51 I-V Curves for Similar PV Devices in Series

For similar PV devices in series:

Vseries = V1 + V2 ….. + Vn

Vseries = V1 x n

Iseries = I1 = I2 ….. = In Current(A) “n” devices 2 devices 1 device in series in series

Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 52 Dissimilar PV Devices in Series

 When dissimilar PV devices are connected in series, the still add, but the current is limited by the lowest current output device in series.

 Not acceptable.

Pos (+) (-) (+) Neg (-) A B

Vseries = VA + VB

Pos (+) Iseries = IA < IB Neg (-)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 53 Connecting PV Devices in Parallel Pos (+)

(+) (+) (+) 1 2 n

(-) (-) (-)

Neg (-)

For PV devices in parallel:

Vparallel = V1 = V2 ….. = Vn (for similar devices)

Vparallel = (V1 + V2 … + Vn) / n

Iparallel = I1 + I2 ….. + In

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 54 I-V Curves for Similar PV Devices in Parallel

For PV devices in parallel: Devices 1+2 in parallel Vparallel = V1 = V2 ….. = Vn (for similar devices)

Vparallel = (V1 + V2 … + Vn) / n

Iparallel = I1 + I2 ….. + In

Current(A) Device 1+2 independently

Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 55 Connecting Dissimilar PV Devices in Parallel

 When PV devices with the same voltage but with different current output are connected in parallel, the individual currents add, and the voltage is the average of devices.

A Vparallel = (VA + VB) / 2

Iparallel = IA + IB

Neg (-) Pos (+)

B

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 56 Connecting Dissimilar PV Devices in Parallel

 Series strings of PV modules with similar voltage but having different current output may be connected in parallel.

For dissimilar current PV devices in parallel:

Devices 1+2 Vparallel = (V1 + V2 … + Vn) / n in parallel

Iparallel = I1 + I2 ….. + In Device 1 Current(A)

Device 2

Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 57 Bypass Diodes

 Bypass diodes are connected in parallel with series strings of cells to prevent cell overheating when cells or parts of an array are shaded.

When cells are not shaded, the When a cells is shaded, the bypass bypass diode is reverse biased and diode is forward biased and conducts does not conduct current current

Neg (-) Pos (+)

Shaded cell

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 58 Without Bypass Diodes

Large power dissipation in module with lower current (failing module)

Current (A) Power produced by module with higher current (healthy module)

operating current

Module 2

Module 1

0 << Negative voltage (reverse bias) Positive voltage (forward bias) >> Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 59 With Bypass Diodes

Low power dissipation in module with lower current (failing module)

Current (A) Power produced by module with higher current (healthy module)

operating current Module 2

Module 1

0 << Negative voltage (reverse bias) Positive voltage (forward bias) >> Voltage (V)

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 60 Module Junction Box with Bypass Diodes

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 61 PV Module Rating Conditions

 The electrical performance of PV modules is rated at Standard Test Conditions (STC):  Irradiance: 1,000 W/m2 , AM 1.5  Cell temperature: 25°C

Source: SolarWorld USA  2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 62 Other PV Module Ratings

 Standard Operating Conditions (SOC)  Irradiance: 1,000 W/m2  Cell temperature: NOCT

 Nominal Operating Conditions (NOC)  Irradiance: 800 W/m2  Cell temperature: NOCT

 Nominal Operating Cell Temperature (NOCT)  Irradiance: 800 W/m2  Ambient Temp: 20°C  PV Array: open-circuit  Wind Speed: 1.0 m/s

 PVUSA Test Conditions (PTC):  1000 W/m², 45°C, 1 m/s

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 63 PV Module Rating Conditions

STC SOC

PTC NOC

Voltage

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 64 Approved Modules

 Certain listed PV modules have been approved as “eligible equipment” for incentive programs.  See: www.gosolarcalifornia.org

 These modules have had additional independent performance tests for PTC ratings.

 Many other states refer to this list for eligible equipment for their incentive programs.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 65 Photovoltaic Module Standards

 Installation Requirements:  National Electrical Code, NFPA 70  Must be installed in accordance with manufacturer’s instructions

 Product Listing  UL 1703: Standard for Safety for Flat-Plate Photovoltaic Modules and Panels

 Design Qualification (reliability testing)  IEC 61215: Crystalline Silicon Terrestrial Photovoltaic (PV) Modules - Design Qualification and Type Approval  IEC 61646: Thin-Film Terrestrial Photovoltaic (PV) Modules - Design Qualification and Type Approval

 Performance Measurement  ASTM E1036: Standard Test Methods for Electrical Performance of Non- concentrator Terrestrial Photovoltaic Modules and Arrays Using Reference Cells

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 66 PV Module Markings

 All PV modules must be marked with the following information [NEC 690.51]:

 Open-circuit voltage  Short-circuit current  Operating voltage  Operating current  Maximum power  Polarity of terminals  Maximum overcurrent device rating  Maximum permissible system voltage

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 67 Fire Classification

 PV modules may be evaluated for external fire exposure for building roof covering materials.

 The fire class is identified in the individual Recognitions as class A, B or C in accordance with UL's Roofing Materials and Systems Directory.

 Modules not evaluated for fire exposure are identified as NR (Not Rated), and not suitable for installation on buildings.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 68 PV Module Design Qualification

 PV modules attaining optional design qualification undergo additional reliability testing that validates long-term warranties.

 The tests include:

 Thermal cycling tests  Humidity - freezing tests  Impact and shock tests  Immersion tests  Cyclic pressure, twisting, vibration and other mechanical loading tests  Wet/dry hi-pot, excessive and reverse current electrical tests  Other electrical and mechanical tests.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 69 Module Installation Instructions

 Listed PV modules must be installed in accordance with instructions provided (shipped) with product.

 Includes safety information, working with PV modules during sun hours (energized electrical equipment), mounting configurations, and electrical wiring and grounding instructions.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 70 PV Module Safety

 Most manufacturer’s literature states that module installation should be done by qualified, licensed electrical professionals.

 Safety precautions for installing PV modules include:  Do not insert electrically conducting parts into the plugs or sockets.  Do not wear metallic jewelry while performing installation.  Do not fit solar modules and wiring with wet plugs and sockets. Tools and working conditions must be dry.  Exercise extreme caution when carrying out work on wiring and use the appropriate safety equipment (insulated tools/gloves, fall protection, etc.)  Do not use damaged modules. Do not dismantle modules. Do not remove any part or label fitted by the manufacturer. Do not treat the rear of the laminate with paint, adhesives or mark it using sharp objects.  Do not artificially concentrate sunlight on modules.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 71 Handling PV Modules

 Care in handling, transporting, storing and installing PV modules includes the following:

 Leave modules in packaging until they are to be installed.  Carry modules with both hands, do not use connectors as a handle  Do not stand modules on hard ground or on their corners  Do not place modules on top of each other or stand on them  Do not mark or work on them with sharp objects  Keep all electrical contacts clean and dry  Do not install modules in high winds

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 72 Module Selection Criteria

 The selection of PV modules for a given project may be based on any number of factors, including:

 Module physical and electrical specifications  Manufacturer certification to quality standards (ISO 9000)  Module warranty and design qualification (IEC 61215/61216)  Customer satisfaction and field results  Company ownership and years in business  Costs and availability

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 73 Summary

 Photovoltaic (PV) cells are semiconductor devices that produce electrical output when exposed to sunlight.

 The current-voltage characteristic (I-V curve) is the basic descriptor of PV device performance.

 The output of a PV device is dependent upon sunlight intensity, temperature and electrical load.

 PV devices are connected in series to build voltage, and in parallel to build current and power output.

 PV modules are installed in accordance with installation instructions and local building codes.

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 74 Questions and Discussion

 2012 Jim Dunlop Solar Cells, Modules and Arrays: 5 - 75