CONTENT : Foreword xi CHAPTER 1 Photovoltaic Basics 1.1 PV array systems and PV applications 1 1.1.1 Overview 1 1.1.2 Stand-alone systems 1 1.1.3 Grid-connected systems 5 1.2 Solar radiation 8 1.2.1 The sun as an energy source 8 1.2.2 Distribution of solar radiation 9 1.2.3 Direct and diffuse radiation 10 1.2.4 Angle definition 11 1.2.5 Solar altitude and solar spectrum 11 1.2.6 Ground reflection 13 1.2.7 How solar radiation is measured 14 1.2.8 Tracking PV arrays 15 1.3 The photovoltaic effect and how solar cells work 19 1.3.1 How a solar cell works 19 1.3.2 Design and functioning of a crystalline silicon solar cell 21 1.4 Solar cell types 23 1.4.1 Crystalline silicon 23 1.4.2 Mono-crystalline (single-crystal) silicon cells 24 1.4.3 Polycrystalline silicon cells 26 1.4.4 Ribbon-pulled silicon cells 27 1.4.5 Anti-reflective coating on crystalline silicon cells 30 1.4.6 Front contacts 31 1.4.7 Back contacts 33 1.4.8 High-performance cells 34 1.4.9 Thin-film cell technology 40 1.4.10 Amorphous silicon cells 42 1.4.11 Copper indium diselenide (CIS) cells 43 1.4.12 Cadmium telluride (CdTe) cells 44 1.4.13 Thin-film solar cells made from crystalline silicon 48 1.4.14 Concentrating systems 49 1.4.15 Hybrid cells: HIT solar cells 51 1.4.16 Comparison of solar cell types and trends 52 1.5 Electrical properties of solar cells 53 1.5.1 Equivalent circuit diagrams of solar cells 53 1.5.2 Cell parameters and solar cell characteristic /-V curves 56 1.5.3 Spectral sensitivity 60 1.5.4 Efficiency of solar cells and PV modules 62 CHAPTER 2 PV Modules and Other Components of Grid-Connected Systems 2.1 PV modules 65 2.1.1 Cell stringing 65 2.1.2 Cell encapsulation 67 2.1.3 Types of modules 72 2.1.4 Design options for PV modules 75 2.1.5 Module cable outlets and junction boxes 84 2.1.6 Wiring symbols 84 2.1.7 Characteristic 7-V curves for modules 85 2.1.8 Irradiance dependence and temperature characteristics 87 2.1.9 Hot spots, bypass diodes and shading 89 2.1.10 Electrical characteristics of thin-film modules 93 2.1.11 Quality certification for modules 98 2.1.12 Interconnection of PV modules 100 2.2 PV array combiner/junction boxes, string diodes and fuses 101 2.3 Grid-connected inverters 103 2.3.1 Wiring symbol and method of operation 103 2.3.2 Grid-controlled inverters 105 2.3.3 Self-commutated inverters 106 2.3.4 Characteristics, characteristic curves and properties of grid-connected inverters 109 2.3.5 Grid-connected inverter types and construction sizes in various power classes 117 2.3.6 Further developments in grid-connected inverter technology 118 2.4 Cabling, wiring and connection systems 123 2.4.1 Module and string cables 123 2.4.2 Connection systems 124 2.4.3 DC main cable 126 2.4.4 AC connection cable 126 2.5 Direct current load switch (DC main switch) 126 2.6 AC switch disconnector 127 2.6.1 Miniature circuit breaker (MCBs) 127 2.6.2 Earth leakage circuit breaker 127 CHAPTER 3 Site Surveys and Shading Analysis 3.1 On-site visit and site survey 129 3.2 Consulting with the customer 130 3.3 Shadow types 131 3.3.1 Temporary shading 131 3.3.2 Shading resulting from the location 133 3.3.3 Shading resulting from the building 133 3.3.4 Self-shading 134 3.3.5 Direct shading 135 3.4 Shading analysis 137 3.4.1 Using a site plan and sun path diagram 137 3.4.2 Using a sun path diagram on acetate 137 3.5 Shade analysis tools using software 139 3.6 Shading, PV-array configuration and system concept 141 3.6.1 Connection in series (string concept) 142 3.6.2 Connection in parallel 142 3.6.3 Comparison of connection concepts 142 3.7 Shading with free-standing/rack-mounted PV arrays 144 3.7.1 Reducing the mutual shading losses of rack-mounted PV modules 145 3.8 Checklists for building survey 146 3.8.1 PV system checklist 147 3.8.2 PV generator, inverter and meter 148 3.8.3 Lines and installation 149 3.8.4 Other 149 3.8.5 Shading checklist 149 CHAPTER 4 Planning and Sizing Grid-Connected Photovoltaic Systems 4.1 System size and module choice 151 4.2 System concepts 152 4.2.1 Central inverter concept 153 4.2.2 Sub-array and string inverter concept 155 4.2.3 Module inverter concept 156 4.3 Inverter installation site 158 4.4 Sizing the inverter 159 4.4.1 Choosing the number and power rating of inverters 159 4.4.2 Voltage selection 161 4.4.3 Determining the number of strings 161 4.4.4 Sizing using simulation programs 164 4.5 Selecting and sizing cables for grid-tied PV systems 165 4.5.1 Cable voltage ratings 166 4.5.2 Cable current carrying capacity 166 4.5.3 Minimizing the cable losses/voltage drops 167 4.5.4 Sizing the module and string cabling 167 4.5.5 Sizing the DC main cable 170 4.5.6 Sizing the AC connection cable 171 4.6 Selection and sizing of the PV array combiner/junction box and the DC main disconnect/isolator switch 172 4.7 Lightning protection, earthing/grounding and surge protection 173 4.7.1 Lightning protection - direct strikes 175 4.7.2 Indirect lightning effects and internal lightning protection 176 4.8 Yield forecast 178 CHAPTER 5 System Sizing, Design and Simulation Software 5.1 Use of sizing, design and simulation programs 181 5.2 Checking the simulation results 182 5.3 Simulation of shading 183 5.4 Market overview and classification 183 5.5 Programme descriptions 184 5.5.1 Calculation programs 184 5.5.2 Time-step simulation programs 185 5.5.3 Simulation systems 194 5.5.4 Supplementary programs and data sources 195 5.5.5 Design and service programs 197 5.5.6 Web-based simulation programs 198 CHAPTER 6 Mounting Systems and Building Integration 6.1 Introduction 199 6.2 Roof Basics 200 6.2.1 The roofs tasks 200 6.2.2 Roof shapes 200 6.2.3 Roof constructions 201 6.2.4 Roof skin 202 6.2.5 Sloping roof 206 6.2.6 Flat roof 207 6.3 Sloping roofs 209 6.3.1 On-roof systems 209 6.3.2 In-roof systems 221 6.4 Flat roofs 224 6.4.1 On-roof systems for flat roofs 224 6.4.2 Roof-integrated systems 234 6.5 Facade basics 235 6.5.1 External wall structure 235 6.5.2 Facade types 237 6.5.3 Facade structures and construction methods 238 6.5.4 Fastenings 242 6.5.5 Joints and joint sealing 243 6.6 Photovoltaic facades 244 6.6.1 Mounting modules on existing facades 245 6.6.2 Facades with integrated modules 246 6.7 Glass roofs 257 6.8 Solar protection devices 263 6.8.1 Module fixing 264 6.8.2 Fixed solar shading 264 6.8.3 Moveable solar shading 267 6.9 Mounting systems for free-standing installations 270 CHAPTER 7 Installing, Commissioning and Operating Grid-Connected Photovoltaic Systems 7.1 General installation notes 273 7.1.1 Notes on DC installation 273 7.1.2 Notes on module mounting 273 7.1.3 Notes on module interconnection 275 7.1.4 Notes on cable laying 275 7.2 Example installation of a grid-connected PV system 276 7.2.1 Preparation 276 7.2.2 System installation: Step by step 277 7.3 Guarantee 283 7.4 Breakdowns, typical faults and maintenance for PV systems 285 7.4.1 Maintenance 285 7.4.2 Maintenance and upkeep checklist 286 7.5 Troubleshooting 287 7.6 Monitoring operating data and presentation 288 7.6.1 Internet-based system evaluation 291 7.6.2 Web-based data transmission and evaluation 292 7.6.3 Presentation and visualization 292 7.7 Long-term experience and quality 293 7.7.1 Long-term behaviour of PV modules 293 7.7.2 Quality and reliability of inverters 294 CHAPTER 8 Stand-alone Photovoltaic Systems 8.1 Introduction 295 8.2 Modules in stand-alone PV systems 298 8.3 Batteries in stand-alone PV systems 298 8.3.1 How lead-acid batteries work: Construction and operating principles 298 8.3.2 Types and designs of lead-acid batteries 300 8.3.3 Operating behaviour and characteristics of lead-acid batteries 303 8.3.4 Ageing effects 307 8.3.5 Selection criteria 307 8.3.6 Battery safety and maintenance 307 8.3.7 Recycling 310 8.4 Charge controllers 310 8.4.1 Series controllers 311 8.4.2 Shunt controllers (parallel controllers) 312 8.4.3 Deep discharge protection 312 8.4.4 MPP charge controllers 313 8.5 Stand-alone inverters 313 8.5.1 Sine-wave inverters 315 8.5.2 Modified sine-wave'inverters 315 8.5.3 Square-wave inverters 315 8.5.4 Application criteria for inverters in stand-alone systems 315 8.6 Planning and designing stand-alone systems 316 8.6.1 Direct coupling of PV array, battery and loads 316 8.7 Measuring electricity consumption 317 8.8 Sizing the PV array 318 8.8.1 Model for calculating the yield of a PV array 318 8.8.2 Cable, conversion and adjustment losses 320 8.8.3 Summary of the design outcome 321 8.8.4 Brief summary of the calculation method for designing a PV array, taking the example of the small holiday home 322 8.9 Sizing of the cable cross sections 323 8.9.1 Charge controller cable 325 8.10 Battery sizing 325 8.11 Use of an inverter 326 8.12 Photovoltaics in decentral electricity grids/mini-grids 327 8.12.1 DC-coupled systems 328 8.12.2 AC-coupled systems 329 CHAPTER 9 Economics and Environmental Issues 9.1 Cost trends 331 9.2 Technological trends 332 9.3 Economic Assessment 333 9.3.1 Power production costs 333 9.4 Environmental impact 335 9.4.1 Energy payback and harvest factor 335 9.4.2 Pollutants in the production process 336 9.4.3 Module recycling concepts 337 CHAPTER 10 Marketing and Promotion 10.1 Marketing PV: The basics 341 10.1.1 Customer orientation: The central theme 341 10.1.2 The iceberg principle 342 10.1.3 The pull concept 342 10.2 Greater success through systematic marketing 343 10.2.1 The benefits come first 343 10.2.2 The four pillars of the marketing concept 344 10.2.3 Range of marketing options 347 10.2.4 Six steps to the target 353 10.3 A good sales talk is fun 358 10.3.1 What does'successful selling'mean? 358 10.3.2 Build a bridge 359 10.3.3 Find out the customer's requirements 360 10.3.4 Offer solutions 362 10.3.5 Achieve the result 362 Bibliography 367 Index 371