R&D INTO STAND-ALONE PV SYSTEMS FOR EXPORT ETSU S/P2/00205/REP Contractor IT Power Ltd The work described in this report was carried out under contract as part of the New and Renewable Energy Programme, managed by the Energy Technology Support Unit (ETSU) on behalf of the Department of Trade and Industry. The views and judgements expressed in this report are those of the contractor and do not necessarily reflect those of ETSU or the Department of Trade and Industry. First published 1996 CONTENTS ^COMPLETE REPORT NOT AVAILABLE ELECTRONICALLY* EXECUTIVE SUMMARY i Introduction i The Technology i Applications i User Experiences ii The Market iii Barriers to the Uptake of PV iii PV Economics iii Technical Regulations and Standards iv 1. INTRODUCTION AND BACKGROUND 1 1.1. Introduction 1 1.2. Purpose of this Report 3 1.2.1. Background 3 1.2.2. Aims of the Report 3 1.2.3. Benefits to the UK PV industry 3 1.2.4. Deliverables 4 1.2.5. Meetings 4 1.3. The IEA Photovoltaic Power Systems Programme 5 1.4. Aim of Task III 5 2. PHOTOVOLTAIC TECHNOLOGY 7 2.1. Background 7 2.1.1. Mono-crystalline silicon cells 8 2.1.2. Poly-crystalline silicon cells 8 2.1.3. Amorphous silicon cells 9 2.1.4. Photovoltaic modules 10 2.2. The Solar Resource 10 2.2.1. Definition of Terms 10 2.2.2. Energy from photovoltaic modules 11 2.2.3. System sizing 12 2.3. Stand-Alone PV Systems 12 2.3.1. Definition of a PV system 12 2.3.2. PV system components 13 2.3.3. Sizing 15 2.3.4. Installation 16 2.3.5. Maintenance requirements 16 2.3.6. Operating PV systems 17 2.3.7. PV system applications 17 2.4. Environmental and safety considerations 18 2.4.1. PV modules and the environment 18 2.4.2. Energy payback ratio of PV modules 19 2.4.3. Environmental concerns of PV system components 19 2.4.4. CO2 emissions 19 2.4.5. Safety issues 20 2.5. Future development 22 2.5.1. Future Prospects for Module Efficiencies and Costs 23 3. APPLICATIONS FOR STAND-ALONE PHOTOVOLTAIC SYSTEMS 25 3.1. Introduction 25 3.2. Service Applications 25 3.2.1. Telecommunications 25 3.2.2. Cathodic Corrosion Protection 26 3.2.3. Telemetry Systems 27 3.2.4. Navigation Aids 28 3.2.5. Pumping systems 29 3.2.6. Water treatment systems 32 3.2.7. Refrigeration systems 33 3.2.8. Battery charging systems 35 3.2.9. Health care 37 3.2.10. Other systems 37 3.3. Isolated Buildings 38 3.3.1. Solar Home Systems (SHS) 38 3.3.2. Remote Area Power Supply (RAPS) Systems 40 3.4. Island Systems 41 4. BALANCE OF SYSTEM COMPONENTS AND APPLIANCES 43 4.1. Introduction 43 4.2. Inverters 43 4.3. Batteries 45 4.4. Charge Controllers 49 4.5. High Efficiency Appliances 51 4.5.1. Products which are widely available 51 4.5.2. Appliances Required for PV Systems 52 4.5.3. Appliances only required for RAPS-type PV systems 53 4.5.4. Appliances currently being researched 53 4.5.5. Developing Countries - appliance availability 53 5. STAND-ALONE SYSTEMS INSTALLED AND USER EXPERIENCES 54 5.1. Introduction 54 5.2. Service Applications 54 5.2.1. Industrial Systems 54 5.2.2. PV Systems in Agriculture and Fisheries 59 5.2.3. Health Care 60 5.2.4. Drinking Water Supply 63 5.2.5. Consumer Applications 66 5.3. Isolated Buildings 66 5.4. Island Systems 73 6. THE PV INDUSTRY AND MARKET 76 6.1. Historical review of Global PV market development 76 6.1.1. Non-electrified populations: a primary PV market potential 80 7. BARRIERS TO THE WIDER DISSEMINATION OF PV SYSTEMS 82 7.1. Introduction 82 7.2. Results from Survey 82 7.2.1. General Barriers 83 7.2.2. PV company activities 84 7.2.3. Government involvement with PV 85 7.2.4. Utility involvement with PV systems 85 7.3. Technical factors 87 7.3.1. Inherent limitations of solar energy 87 7.3.2. Site and geographical locations 88 7.3.3. Quality of systems 88 7.3.4. Warranty on PV modules 89 7.3.5. Size range of systems 89 7.3.6. Quality of installation 89 7.3.7. Maintenance and after-sales services 89 7.4. Economic Factors 90 7.5. Social factors 90 7.5.1. User participation 90 7.5.2. Local management 91 7.5.3. Educational requirements 91 7.5.4. System abuse 91 7.5.5. Negative social effects 92 7.6. Institutional factors 92 7.6.1. Operational constraints 92 7.6.2. Price & financing constraints 97 8. PV ECONOMICS 102 8.1. Introduction 102 8.1.1. Financial or economic 102 8.1.2. Cost-effectiveness 103 8.1.3. Life-cycle costing 105 8.1.4. Example life-cycle costing : PV lighting kit vs. 2 kerosene lamps 106 8.1.5. Example: comparison of portable lighting systems 108 8.1.6. Life-cycle cost and sensitivity analysis for other PV systems 110 8.1.7. PV pumping system vs. diesel pumping 110 8.1.8. PV refrigerator vs. kerosene refrigerator 111 8.1.9. Critical factors affecting PV system economics 113 8.1.10. Financing options 114 9. TECHNICAL REGULATIONS AND STANDARDS 118 9.1. Introduction 118 9.2. IEC - International Electrotechnical Commission 119 9.3. European Community - ESTI- JRC Ispra 119 9.4. PV module qualification testing 119 9.5. PV system monitoring 120 9.6. Missing Standards for PV systems, typical application designs andBOS components121 9.7. Electrical safety standards applicable to PV technology 122 9.7.1. Protection of human beings against electric shock 122 9.7.2. Protection against overload and short-circuit conditions 123 9.7.3. Lightning and overvoltage protection 124 9.8. Conflict areas between electrical safety standards and PV technology 124 9.8.1. Peculiarities of PV technology 124 9.8.2. Protective measures for Personal safety 124 9.8.3. Overcurrent and short-circuit protection 126 9.8.4. Overvoltage protection 126 10. CONCLUSIONS AND RECOMMENDATIONS 128 10.1. Experiences 128 10.2. Applications 128 10.3. Environmental impact 129 10.4. Installation, operation and maintenance 129 10.5. Critical factors 129 10.6. Economics 130 10.7. Institutional barriers 132 10.8. Future needs 133 11. SOURCES OF FURTHER INFORMATION 134 FIGURES 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 3-1, 3-2, 3-3, 3-4, 8-2, 8-3, 8-4, 8-5 NOT AVAILABLE ELECTRONICALLY TABLE 2-1 NOT AVAILABLE ELECTRONICALLY EXECUTIVE SUMMARY INTRODUCTION Photovoltaics (PV) are used to power a wide variety of applications ranging from small consumer products such as pocket calculators, to the supply of whole villages. One of the primary applications of PV systems is to provide power at locations where mains electricity is not available. Such systems are commonly called stand-alone PV systems. This report presents the current status of PV technology, describes typical applications and experiences with installed stand-alone systems, and then looks at economic issues and barriers to the wider utilisation of PV systems. Research on stand-alone PV systems is included in the International Energy Agency’s (IEA) Photovoltaic Power Systems (PVPS) programme. This report has been prepared by IT Power for the Energy Technology Support Unit (ETSU) on behalf of the Department of Trade and Industry (DTI) under Agreement No. S/P2/00205/00/00. It describes the work carried out by IT Power over the period February 1994 to April 1995 for the UK participation in Task III of the International Energy Agency’s Photovoltaic Power Systems Programme (IEA-PVPS). In order to obtain a comprehensive picture of the status of the technology and the market for stand-alone PV systems, a survey was carried out as part of this research programme. Issues such as real and perceived barriers to the use of PV systems and experiences of actual PV users were also examined. It is intended that this document presents a detailed status report on stand-alone photovoltaic systems. THE TECHNOLOGY Photovoltaic cells absorb light and convert it directly into electrical energy. For most applications, a number of cells are combined to form a PV module. Commercially available modules use monocrystalline, polycrystalline or amorphous silicon technology, although other thin-film technologies such as for instance cadmium telluride will soon be available. The energy output of PV cells or modules varies with the amount of light they receive. In order to obtain a constant supply of electricity, some form of energy storage is required. Usually rechargeable batteries are used for energy storage. Charging of the batteries needs to be controlled. If AC electricity is required, an inverter is also required. Therefore a typical stand-alone PV system usually consists of a PV array made up of one or several PV modules, a battery and a charge controller, and often also an inverter. These components are all readily available as commercial products. The quality of these products varies - they are available as high-quality industrial components, but cheaper consumer-quality products are also on the market. Further research is necessary for all components in order to improve their performance and quality. APPLICATIONS There are numerous applications where stand-alone PV systems can be used as a power supply option.