VDE PHOTOVOLTAICS. electrosuisse^> Verlag SYSTEM DESIGN AND PRACTICE VERLAG. Heinrich Häberlin. Translated by Herbert Eppel

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1 PHOTOVOLTAICS SYSTEM DESIGN AND PRACTICE Heinrich Häberlin Berne University of Applied Sciences, Switzerland Translated by Herbert Eppel HE Translations, Leicester, UK VDE electrosuisse^> Verlag VERLAG

2 Foreword Preface About the Author Acknowledgements Note on the Examples and Costs List of Symbols xiii xv xvii xix xxi xxiii 1 Introduction Photovoltaics - What's It All About? Overview of this Book A Brief Glossary of Key PV Terms Relevant Terminology Relating to Meteorology, Astronomy and Geometry PV Terminology Recommended Guide Values for Estimating PV System Potential Solar Cell Efficiency r) PV Solar Module Efficiency v\ M Energy Efficiency (Utilization Ratio, System Efficiency) ц Е Annual Energy Yield per Installed Kilowatt of Peak Installed Solar Generator Capacity PV Installation Space Requirements Cost per Installed Kilowatt of Peak Power Feed-in Tariffs; Subsidies Worldwide Solar Cell Production Installed Peak Capacity The Outlook for Solar Cell Production Examples Bibliography 25 2 Key Properties of Solar Radiation Sun and Earth Solar Declination The Apparent Path of the Sun Extraterrestrial Radiation 31

3 viii Contents Radiation on the Horizontal Plane of the Earth's Surface 2.3.I Irradiated Energy H on the Horizontal Plane of the Earth's Surface Simple Method for Calculating Solar Radiation on Inclined Surfaces Annual Global Irradiation Factors Elementary Radiation Calculation Examples for Inclined Surfaces Radiation Calculation on Inclined Planes with Three-Component Model Components of Global Radiation on the Horizontal Plane Radiation Reflected off the Ground The Three Components of Radiation on Inclined Surfaces Approximate Allowance for Shading by the Horizon Effect of Horizon and Facade/Roof Edge Elevation on Diffuse Radiation (Sky and Reflected Radiation) Total Energy Incident on Inclined Surfaces (Generic Case) Retrospective Calculation of Irradiance Incident on Inclined Solar Generators, Using Global Radiation Readings on the Horizontal Plane Examples of Radiation Calculations with the Three-Component Method Approximate Annual Energy Yield for Grid-Connected PV Systems Examples for Approximate Energy Yield Calculations Composition of Solar Radiation Solar Radiation Measurement Pyranometers Reference Cells Pyranometer Versus Reference Cell Measurements Bibliography Solar Cells: Their Design Engineering and Operating Principles The Internal Photoelectric Effect in Semiconductors A Brief Account of Semiconductor Theory Semiconductor Doping The P-N Junction Characteristic Curves of Semiconductor Diodes The Solar Cell: A Specialized Semiconductor Diode with a Large Barrier Layer that is Exposed to Light Structure of a Crystalline Silicon Solar Cell Equivalent Circuit of a Solar Cell Characteristic Curves of Solar Cells Solar Cell Efficiency Spectral Efficiency t] s (of Solar Cells with a Single Junction) Theoretical Efficiency ц т (of Solar Cells with a Single Junction) Practical Efficiency n PV (at a Junction) Efficiency Optimization Methods The Most Important Types of Solar Cells and the Attendant Manufacturing Methods Crystalline Silicon Solar Cells Gallium Arsenide Solar Cells Thin-Film Solar Cells Dye Sensitized Solar Cell (DSSC; Photoelectrochemical Solar Cells, Grätzel Solar Cells) Bifacial Solar Cells Examples Bibliography

4 ix Solar Modules and Solar Generators Solar Modules Potential Solar Cell Wiring Problems Characteristic Curves of Solar Cells in all Quadrants Wiring Solar Cells in Series Parallel-Connected Solar Cells Interconnection of Solar Modules and Solar Generators Series Connection of Solar Modules to a String Parallel-Connected Solar Modules Solar Generators with Parallel-Connected Series Strings Solar Generators with Solar Module Matrixing Solar Generator Power Loss Resulting from Partial Shading and Mismatch Loss Power Loss Induced by Module Shading Mismatch Loss Attributable to Manufacturing Tolerances Mismatch Loss Attributable to String Inhomogeneity Solar Generator Structure Solar Generator Mounting Options Mounting Systems Electrical Integration of Solar Generators DC Wiring Power Loss Grounding Problems on the DC Side Structure of Larger-Scale Solar Generators Safety Protection Against Touch Voltage Factors that Reduce Solar Generator Power Yield Examples Bibliography 221 PV Energy Systems Stand-alone PV Systems PV System Batteries Structure of Stand-alone PV Systems PV Installation Inverters Stand-alone Installation DC Appliances Stand-alone 230 V AC PV Installations Stand-alone PV Installations with Integrated AC Power Busses Grid-Connected Systems Grid-Connected Operation Design Engineering and Operating Principles of PV System Inverters Standards and Regulations for Grid-Connected Inverters Avoidance of Islanding and Stand-alone Operation in Grid Inverters Operating Performance and Characteristics ofpv Grid Inverters Problems that Occur in Grid-Connected Systems and Possible Countermeasures Regulation and Stability Problems in Grid Systems Bibliography 389 Protecting PV Installations Against Lightning Probability of Direct Lightning Strikes Specimen Calculation for the Annual Number of Direct Lightning Strikes N D 397

5 6.2 Lightning Strikes: Guide Values; Main Effects Types of Lightning Effects of Lightning Lightning Protection Installation Classes and Efficiency Use of Approximate Solutions for Lightning Protection Sizing Basic principles of Lightning Protection Internal and External Lightning Protection Protection Zone Determination Using the Lightning Sphere Method Protection Zone for Lightning Conductors and Lightning Rods Lightning Protection Measures for Electricity Installations Shunting Lightning Current to a Series of Down-conductors Potential Increases; Equipotential Bonding Equipotential Bonding Realization Lightning Current in Conductors that are Incorporated into the Equipotential Bonding Installation Lightning Protection Devices Lightning-Current-Induced Voltages and Current Mutual Inductance and Induced Voltages in a Rectangular Loop Proximity Between Down-conductors and other Installations Induced Current Voltages in Lightning-Current-Conducting Cylinders PV Installation Lightning Protection Experiments Introduction The Surge Current Generator Test Apparatus for Solar Module Characteristic Curves Solar Cell and Solar Module Damage Induced by Surge Current Improving Module Immunity to Lightning Current Mini-lightning Conductors for PV Installations Measurement of Induced Voltage in Individual Modules Voltage Induced in Wired Solar Generators Conclusions Drawn from the Test Results Optimal Sizing of PV Installation Lightning Protection Devices Solar Module Mutual Inductance Wiring Mutual Inductance Specimen Calculation for M s and v max in a Whole String Effects of Distant Lightning Strikes Recommendations for PV Installation Lightning Protection Possible Protective Measures Protection Against Distant Lightning Strikes Protection Against Both Distant and Nearby Strikes (up to about 20 m) Protection Against Direct Lightning Strikes on PV Installations and Buildings Lightning Protection for Large-Scale Ground-Based PV Installations Lightning Protection for PV Installations on Flat Roofs PV Installation Lightning Protection as Prescribed by Swiss Law Recap and Conclusions Bibliography 485

6 7 Normalized Representation of Energy and Power of PV Systems Introduction Normalized Yields, Losses and Performance Ratio Normalized Yields Definition of Normalized Losses Performance Ratio New Normalized Values of Merit Normalized Diagrams for Yields and Losses Normalized Monthly and Annual Statistics Normalized Daily Statistics Broken Down by Hours Normalized PV Installation Power Output Normalized Daily Diagram with Instantaneous Values Derivation of Daily Energy Yield from Normalized Instantaneous Values Definition of the Correction Factors k G, k T and of efficiency n r Assessment Methods Using Normalized Daily Diagrams Specimen Normalized Daily Diagrams Anomaly Detection Using Various Types of Diagrams Recap and Conclusions Bibliography PV Installation Sizing Principal of and Baseline Values for Yield Calculations Insolation Calculations Determination of the Temperature Correction Factor k T Defining the Solar Generator Correction Factor k G Energy Yield Calculation for Grid-Connected Systems Examples of Grid-Connected System Energy Yield Sizing PV Installations that Integrate a Battery Bank Determination of Mean Daily Appliance Power Consumption Requisite Battery Capacity К Solar Generator Sizing Stand-alone System Sizing Tables Sizing Exercises for Stand-alone Installations Insolation Calculation Freeware PVGIS Solar Irradiation Data The European Satel-Light Insolation Database Simulation Software Bibliography The Economics of Solar Power How Much Does Solar Energy Cost? Examples of More Exact Energy Price Calculations Comparison of PV and Conventional Electricity Costs PV Electricity Pump Storage System Costs PV Electricity Battery Storage Costs Grey Energy; Energy Payback Time; Yield Factor Bibliography Performance Characteristics of Selected PV Installations Energy Yield Data and Other Aspects of Selected PV Installations Gfeller PV Installation in Burgdorf Switzerland Mont Soleil PV Installation in the Jura Mountains (Elevation 1270 m) 572

7 xii Contents Jungfraujoch PV Installation (Elevation: 3454 m) Birg PV Installation (Elevation: 2670 m) Stade de Suisse PV Installation in Bern Newtech PV Installation with Thin-Film Solar Cell Modules Neue Messe PV Installation in Munich, Germany Leipziger Land PV Installation Borna PV Installation with Biaxial Solar Trackers Erlasee Solar Park with Biaxial Solar Trackers Guadix PV Installation in Southern Spain, with Biaxial Solar Trackers Biaxial Solar Tracker ENEA PV Installation near Naples, Italy PV Installation in Mudgee, Australia PV Installation in Springerville, Arizona Long-Term Comparison of Four Swiss PV Installations Long-Term Energy Yield of the Burgdorf Installation Mean PV Installation Energy Yield in Germany Bibliography In Conclusion Appendix A: Calculation Tables and Insolation Data 633 Al Insolation Calculation Tables 633 A 1.1 Basic Insolation Calculation 633 Al.2 Insolation Calculation Using the Three-Component Model 633 A2 Aggregate Monthly Horizontal Global Insolation 634 A3 Global Insolation for Various Reference Locations 634 A4 R B Factors for Insolation Calculations Using the Three-Component Model 648 A5 Shading Diagrams for Various Latitudes 673 A6 Energy Yield Calculation Tables 676 A6.1 Energy Yield Calculation Tables for Grid-Connected Systems 677 A6.2 Stand-alone Installation Sizing Tables 679 A7 k T and k G Figures for Energy Yield Calculations 681 A7.1 k T Figures for Various Reference Stations 682 A7.2 k G Figures for Various Reference Stations 682 A8 Insolation and Energy Yield Calculation Maps 683 AS. 1 Specimen Polar Shading Diagram 683 A8.2 Insolation Maps 683 A8.3 Maps for Estimates of Annual PV Energy Yield in Europe and Environs 689 Appendix B: Links; Books; Acronyms; etc. 691 В1 Links to PV Web Sites 691 В 1.1 Organizations 691 B1.2 Government Organizations 692 B1.3 Research Organizations 692 В 1.4 Specialized Journals 692 B2 Books on Photovoltaics and Related Areas 693 B3 Acronyms 695 B4 Prefixes for Decimal Fractions and Metric Multiples 696 B5 Conversion Factors 696 B6 Key Physical Constants 696 Index 697