Photovoltaics : Fundamentals, Technology, and Practice

A comprehensive tutorial on photovoltaic technology now fully updated to include solar storage and the latest methods for on-site plant measurements Starting with the basic principles of solar energy, this fully updated, practical text explains the fundamentals of semiconductor physics and the structure and functioning of the solar cell. It describes the latest measurement techniques for solar modules, and the planning and operation of grid-connected and off-grid PV systems. It also looks at other thin film cells, hybrid wafer cells, and concentrator systems. Additionally, this Second Edition covers solar modules and solar generators; system technology of grid connected plants; the storage of solar energy; photovoltaic measurement technology; the planning and operation of grid-connected systems; economic efficiency of PV systems; and the future development of PV. Presents the latest advances in PV R&D and industry deployment Updated illustrations and tabular data reflect current state-of-the-art and PV technology efficiencies Offers expanded tutorial sections to aid teaching and self-study Includes a brand-new chapter on Solar Energy Storage Features two enlarged chapters―one on up-to-date photovoltaic metrology and the other on the future developments in photovoltaics Comes along with the accompanying website www.textbook-pv.org which offers free downloadable figures of the book, solutions of exercises, additional free PV software etc. Developed to prepare engineering students for the PV industry, this practical text is an essential PV primer. Cover Title Page Copyright Contents Preface to the First International Edition Preface to the Second International Edition Abbreviations Chapter 1 Introduction 1.1 Introduction 1.1.1 Why Photovoltaics? 1.1.2 Who Should Read This Book? 1.1.3 Structure of the Book 1.2 What Is Energy? 1.2.1 Definition of Energy 1.2.2 Units of Energy 1.2.3 Primary, Secondary, and End Energy 1.2.4 Energy Content of Various Substances 1.3 Problems with Today's Energy Supply 1.3.1 Growing Energy Requirements 1.3.2 Tightening of Resources 1.3.3 Climate Change 1.3.4 Hazards and Disposal 1.4 Renewable Energies 1.4.1 The Family of Renewable Energies 1.4.2 Advantages and Disadvantages of Renewable Energies 1.4.3 Previous Development of Renewable Energies 1.5 Photovoltaics – The Most Important in Brief 1.5.1 What Does "Photovoltaics" Mean? 1.5.2 What Are Solar Cells and Solar Modules? 1.5.3 How Is a Typical Photovoltaic Plant Structured? 1.5.4 What Does a Photovoltaic Plant "Bring?" 1.6 History of Photovoltaics 1.6.1 How It all Began 1.6.2 The First Real Solar Cells 1.6.3 From Space to Earth 1.6.4 From Toy to Energy Source Chapter 2 Solar Radiation 2.1 Properties of Solar Radiation 2.1.1 Solar Constant 2.1.2 Spectrum of the Sun 2.1.3 Air Mass 2.2 Global Radiation 2.2.1 Origin of Global Radiation 2.2.2 Contributions of Diffuse and Direct Radiation 2.2.3 Global Radiation Maps 2.3 Calculation of the Position of the Sun 2.3.1 Declination of the Sun 2.3.2 Calculating the Path of the Sun 2.4 Radiation on Tilted Surfaces 2.4.1 Radiation Calculation with the Three‐component Model 2.4.1.1 Direct Radiation 2.4.1.2 Diffuse Radiation 2.4.1.3 Reflected Radiation 2.4.2 Radiation Estimates with Diagrams and Tables 2.4.3 Yield Gain through Tracking 2.5 Radiation Availability and World Energy Consumption 2.5.1 The Solar Radiation Energy Cube 2.5.2 The Sahara Miracle Chapter 3 Fundamentals of Semiconductor Physics 3.1 Structure of a Semiconductor 3.1.1 Bohr's Atomic Model 3.1.2 Periodic Table of Elements 3.1.3 Structure of the Silicon Crystal 3.1.4 Compound Semiconductors 3.2 Band Model of a Semiconductor 3.2.1 Origin of Energy Bands 3.2.2 Differences in Isolators, Semiconductors, and Conductors 3.2.3 Intrinsic Carrier Concentration 3.3 Charge Transport in Semiconductors 3.3.1 Field Currents 3.3.2 Diffusion Currents 3.4 Doping of Semiconductors 3.4.1 n‐Doping 3.4.2 p‐Doping 3.5 The p–n Junction 3.5.1 Principle of Method of Operation 3.5.2 Band Diagram of the p–n Junction 3.5.3 Behavior with Applied Voltage 3.5.4 Diode Characteristics 3.6 Interaction of Light and Semiconductors 3.6.1 Phenomenon of Light Absorption 3.6.1.1 Absorption Coefficient 3.6.1.2 Direct and Indirect Semiconductors 3.6.2 Light Reflection on Surfaces 3.6.2.1 Reflection Factor 3.6.2.2 Antireflection Coating Chapter 4 Structure and Method of Operation of Solar Cells 4.1 Consideration of the Photodiode 4.1.1 Structure and Characteristics 4.1.2 Equivalent Circuit 4.2 Method of Function of the Solar Cell 4.2.1 Principle of the Structure 4.2.2 Recombination and Diffusion Length 4.2.3 What Happens in the Individual Cell Regions? 4.2.3.1 Absorption in the Emitter 4.2.3.2 Absorption in the Space Charge Region 4.2.3.3 Absorption Within the Diffusion Length of the Electrons 4.2.3.4 Absorption Outside the Diffusion Length of the Electrons 4.2.4 Back‐surface Field 4.3 Photocurrent 4.3.1 Absorption Efficiency 4.3.2 Quantum Efficiency 4.3.3 Spectral Sensitivity 4.4 Characteristic Curve and Characteristic Parameters 4.4.1 Short‐circuit Current ISC 4.4.2 Open‐circuit Voltage VOC 4.4.3 Maximum Power Point (MPP) 4.4.4 Fill Factor (FF) 4.4.5 Efficiency η 4.4.6 Temperature Dependence of Solar Cells 4.5 Electrical Description of Real Solar Cells 4.5.1 Simplified Model 4.5.2 Standard Model (Single‐diode Model) 4.5.3 Two‐diode Model 4.5.4 Determining the Parameters of the Equivalent Circuit 4.6 Considering Efficiency 4.6.1 Spectral Efficiency 4.6.2 Theoretical Efficiency 4.6.3 Losses in Real Solar Cells 4.6.3.1 Optical Losses, Reflection on the Surface 4.6.3.2 Electrical Losses and Ohmic Losses 4.7 High‐efficiency Cells 4.7.1 Buried‐contact Cell 4.7.2 Point‐contact Cell (IBC Cell) 4.7.3 PERL and PERC Cell Chapter 5 Cell Technologies 5.1 Production of Crystalline Silicon Cells 5.1.1 From Sand to Silicon 5.1.1.1 Production of Polysilicon 5.1.1.2 Production of Monocrystalline Silicon 5.1.1.3 Production of Multicrystalline Silicon 5.1.2 From Silicon to Wafer 5.1.2.1 Wafer Production 5.1.2.2 Wafers from Ribbon Silicon 5.1.3 Production of Standard Solar Cells 5.1.4 Production of Solar Modules 5.2 Cells of Amorphous Silicon 5.2.1 Properties of Amorphous Silicon 5.2.2 Production Process 5.2.3 Structure of the Pin Cell 5.2.4 Staebler–Wronski Effect 5.2.5 Stacked Cells 5.2.6 Combined Cells of Micromorphous Material 5.2.7 Integrated Series Connection 5.3 Further Thin Film Cells 5.3.1 Cells of Cadmium‐Telluride 5.3.2 CIS Cells 5.4 Hybrid Wafer Cells 5.4.1 Combination of c‐Si and a‐Si (HIT Cell) 5.4.2 Stacked Cells of III/V Semiconductors 5.5 Other Cell Concepts 5.6 Concentrator Systems 5.6.1 Principle of Radiation Bundling 5.6.2 What Is the Advantage of Concentration? 5.6.3 Examples of Concentrator Systems 5.6.4 Advantages and Disadvantages of Concentrator Systems 5.7 Ecological Questions on Cell and Module Production 5.7.1 Environmental Effects of Production and Operation 5.7.1.1 Example of Cadmium‐Telluride 5.7.1.2 Example of Silicon 5.7.2 Availability of Materials 5.7.2.1 Silicon 5.7.2.2 Cadmium‐Telluride 5.7.2.3 Cadmium Indium Selenide 5.7.2.4 III/V Semiconductors 5.7.3 Energy Amortization Time and Yield Factor 5.8 Summary Chapter 6 Solar Modules and Solar Generators 6.1 Properties of Solar Modules 6.1.1 Solar Cell Characteristic Curve in All Four Quadrants 6.1.2 Parallel Connection of Cells 6.1.3 Series Connection of Cells 6.1.4 Use of Bypass Diodes 6.1.4.1 Reducing Shading Losses 6.1.4.2 Prevention of Hotspots 6.1.5 Typical Characteristic Curves of Solar Modules 6.1.5.1 Variation of the Irradiance 6.1.5.2 Temperature Behavior 6.1.6 Special Case Thin‐film Modules 6.1.7 Examples of Data Sheet Information 6.2 Connecting Solar Modules 6.2.1 Parallel Connection of Strings 6.2.2 What Happens in Case of Cabling Errors? 6.2.3 Losses Due to Mismatching 6.2.4 Smart Installation in Case of Shading 6.3 Direct Current Components 6.3.1 Principle of Plant Construction 6.3.2 Direct Current Cabling 6.4 Types of Plants 6.4.1 Ground‐mounted Plants 6.4.2 Flat‐roof Plants 6.4.3 Pitched‐roof Systems 6.4.4 Facade Systems Chapter 7 System Technology of Grid‐connected Plants 7.1 Solar Generator and Load 7.1.1 Resistive Load 7.1.2 DC/DC Converter 7.1.2.1 Idea 7.1.2.2 Buck Converter 7.1.2.3 Boost Converter 7.1.3 MPP Tracker 7.2 Construction of Grid‐connected Systems 7.2.1 Feed‐in Variations 7.2.2 Plant Concepts 7.3 Construction of Inverters 7.3.1 Tasks of the Inverter 7.3.2 Line‐commutated and Self‐commutated Inverter 7.3.3 Inverters Without Transformers 7.3.4 Inverters with Mains Transformer 7.3.5 Inverters with HF Transformer 7.3.6 Three‐phase Feed‐in 7.3.7 Further Clever Concepts 7.4 Efficiency of Inverters 7.4.1 Conversion Efficiency 7.4.2 European Efficiency 7.4.3 Clever MPP Tracking 7.5 Dimensioning of Inverters 7.5.1 Power Dimensioning 7.5.2 Voltage Dimensioning 7.5.3 Current Dimensioning 7.6 Requirements of the Grid Operators 7.6.1 Prevention of Stand‐Alone Operation 7.6.2 Maximum Feed‐in Power 7.6.3 Reactive Power Provision 7.7 Safety Aspects 7.7.1 Earthing of the Generator and Lightning Protection 7.7.2 Fire Protection Chapter 8 Storage of Solar Energy 8.1 Principle of Solar Storage 8.2 Batteries 8.2.1 Lead‐acid Battery 8.2.1.1 Principle and Build‐up 8.2.1.2 Types of Lead Batteries 8.2.1.3 Battery Capacity 8.2.1.4 Voltage Progression 8.2.1.5 Summary 8.2.2 Charge Controllers 8.2.2.1 Series Controller 8.2.2.2 Shunt Controller 8.2.2.3 MPP Controller 8.2.2.4 Examples of Products 8.2.3 Lithium Ion Battery 8.2.3.1 Principle and Build‐up 8.2.3.2 Reactions During Charging and Discharging 8.2.3.3 Material Combinations and Cell Voltage 8.2.3.4 Safety Aspects 8.2.3.5 Charging Procedures 8.2.3.6 Battery Design 8.2.3.7 Lifespan 8.2.3.8 Application Areas 8.2.3.9 Summary 8.2.4 Sodium Sulfur Battery 8.2.4.1 Principle and Build‐up 8.2.4.2 Peculiarities of the High Temperature Battery 8.2.4.3 Sodium Sulfur Batteries in Practice 8.2.4.4 Summary 8.2.5 Redox Flow Battery 8.2.5.1 Principle and Build‐up 8.2.5.2 Behavior in Practice 8.2.5.3 Concrete Applications 8.2.5.4 Summary 8.2.6 Comparison of the Different Battery Types 8.3 Storage Use for Increase of Self‐consumption 8.3.1 Self‐consumption in Domestic Households 8.3.1.1 Solution Without Storage 8.3.1.2 Solution with Storage 8.3.1.3 Examples of Storage Systems 8.3.1.4 How Much Cost a Kilowatt‐Hour? 8.3.1.5 The Smart Home 8.3.2 Self‐consumption in Commercial Enterprises 8.3.2.1 Example Production Factory 8.3.2.2 Example Hospital 8.4 Storage Deployment from the Point of View of the Grid 8.4.1 Peak‐shaving with Storages 8.4.2 Governmental Funding Program for Solar Storages 8.5 Stand‐alone Systems 8.5.1 Principal Structure 8.5.2 Examples of Stand‐alone Systems 8.5.2.1 Solar Home Systems 8.5.2.2 Hybrid Systems 8.5.3 Dimensioning Stand‐alone Plants 8.5.3.1 Acquiring the Energy Consumption 8.5.3.2 Dimensioning the PV Generator 8.5.3.3 Selecting the Battery Chapter 9 Photovoltaic Metrology 9.1 Measurement of Solar Radiation 9.1.1 Global Radiation Sensors 9.1.1.1 Pyranometer 9.1.1.2 Radiation Sensors from Solar Cells 9.1.2 Measuring Direct and Diffuse Radiation 9.2 Measuring the Power of Solar Modules 9.2.1 Build‐up of a Solar Module Power Test Rig 9.2.2 Quality Classification of Module Flashers 9.2.3 Determination of the Module Parameters 9.3 Peak Power Measurement at Site 9.3.1 Principle of Peak Power Measurement 9.3.2 Possibilities and Limits of the Measurement Principle 9.4 Thermographic Measuring Technology 9.4.1 Principle of Infrared Temperature Measurement 9.4.2 Bright Thermography of Solar Modules 9.4.3 Dark Thermography 9.5 Electroluminescence Measuring Technology 9.5.1 Principle of Measurement 9.5.2 Examples of Photos 9.5.3 Low‐cost Outdoor Electroluminescence Measurements 9.6 Analysis of Potential Induced Degradation (PID) 9.6.1 Explanation of the PID Effect 9.6.2 Test of Modules for PID 9.6.3 EL Investigations to PID Chapter 10 Design and Operation of Grid‐connected Plants 10.1 Planning and Dimensioning 10.1.1 Selection of Site 10.1.2 Shading 10.1.2.1 Shading Analysis 10.1.2.2 Near Shading 10.1.2.3 Self‐shading 10.1.2.4 Optimized String Connection 10.1.3 Plant Dimensioning and Simulation Programs 10.1.3.1 Inverter Design Tools 10.1.3.2 Simulation Programs for Photovoltaic Plants 10.2 Economics of Photovoltaic Plants 10.2.1 The Renewable Energy Law 10.2.2 Return Calculation 10.2.2.1 Input Parameters 10.2.2.2 Amortization Time 10.2.2.3 Property Return 10.2.2.4 Profit Increase Through Self‐consumption of Solar Power 10.2.2.5 Further Influences 10.3 Surveillance, Monitoring, and Visualization 10.3.1 Methods of Plant Surveillance 10.3.2 Monitoring PV Plants 10.3.2.1 Specific Yields 10.3.2.2 Losses 10.3.2.3 Performance Ratio 10.3.2.4 Concrete Measures for Monitoring 10.3.3 Visualization 10.4 Operating Results of Actual Installations 10.4.1 Pitched Roof Installation from 1996 10.4.2 Pitched Roof Installation from 2002 10.4.3 Flat Roof from 2008 Chapter 11 Future Development 11.1 Potential of Photovoltaics 11.1.1 Theoretical Potential 11.1.2 Technically Useful Radiation Energy 11.1.2.1 Roofs 11.1.2.2 Facades 11.1.2.3 Traffic Routes 11.1.2.4 Free Areas 11.1.3 Technical Electrical Energy Generation Potential 11.1.4 Photovoltaics versus Biomass 11.2 Efficient Promotion Instruments 11.3 Price and Feed‐in Tariff Development 11.3.1 Price Development of Solar Modules 11.3.2 Development of Feed‐in Tariffs 11.4 Renewable Energies in Today's Power Supply System 11.4.1 Structure of Electricity Generation 11.4.2 Types of Power Plants and Control Energy 11.4.3 Interplay Between Sun and Wind 11.4.4 Exemplary Electricity Generation Courses 11.5 Thoughts on Future Energy Supply 11.5.1 Consideration of Different Future Scenarios 11.5.2 Options to Store Electrical Energy 11.5.2.1 Pumped Storage Power Plants 11.5.2.2 Compressed Air Storage 11.5.2.3 Battery Storage 11.5.2.4 Electric Mobility 11.5.2.5 Hydrogen as Storage 11.5.2.6 Power to Gas: Methanation 11.5.3 Alternatives to Storage 11.5.3.1 Active Load Management by Smart Grids 11.5.3.2 Expansion of the Electricity Grids 11.5.3.3 Limitation of the Feed‐in Power 11.5.3.4 Use of Flexible Power Plants 11.6 Conclusion Chapter 12 Exercises Appendix A Solar Radiation Diagrams Influence of Orientation and Inclination on the Yearly Radiations Sums for Different Locations Appendix B Checklist for Planning, Installing, and Operating a Photovoltaic Plant Appendix C Physical Constants/Material Parameters Important Physical Constants Material Parameters of Silicon References Further Information on Photovoltaics Index EULA **A comprehensive tutorial on photovoltaic technology now fully updated to include solar storage and the latest methods for on-site plant measurements** Starting with the basic principles of solar energy, this fully updated, practical text explains the fundamentals of semiconductor physics and the structure and functioning of the solar cell. It describes the latest measurement techniques for solar modules, and the planning and operation of grid-connected and off-grid PV systems. It also looks at other thin film cells, hybrid wafer cells, and concentrator systems. Additionally, this __Second Edition__ covers solar modules and solar generators; system technology of grid connected plants; the storage of solar energy; photovoltaic measurement technology; the planning and operation of grid-connected systems; economic efficiency of PV systems; and the future development of PV. * Presents the latest advances in PV R&D and industry deployment * Updated illustrations and tabular data reflect current state-of-the-art and PV technology efficiencies * Offers expanded tutorial sections to aid teaching and self-study * Includes a brand-new chapter on Solar Energy Storage * Features two enlarged chapters―one on up-to-date photovoltaic metrology and the other on the future developments in photovoltaics * Comes along with the accompanying website www.textbook-pv.org which offers free downloadable figures of the book, solutions of exercises, additional free PV software etc.