Photovoltaic Solar Energy: From Fundamentals to Applications

By Angèle Reinders, Pierre Verlinden, Wilfried van Sark and Alexandre Freundlich

Solar PV is now the third most important renewable energy source, after hydro and wind power, in terms of global installed capacity. Bringing together the expertise of international PV specialists Photovoltaic Solar Energy: From Fundamentals to Applications provides a comprehensive and up-to-date account of existing PV technologies in conjunction with an assessment of technological developments.

Key features:

• Written by leading specialists active in concurrent developments in material sciences, solar cell research and application-driven R&D.
• Provides a basic knowledge base in light, photons and solar irradiance and basic functional principles of PV.
• Covers characterization techniques, economics and applications of PV such as silicon, thin-film and hybrid solar cells.
• Presents a compendium of PV technologies including: crystalline silicon technologies; chalcogenide thin film solar cells; thin-film silicon based PV technologies; organic PV and III-Vs; PV concentrator technologies; space technologies and economics, life-cycle and user aspects of PV technologies.
• Each chapter presents basic principles and formulas as well as major technological developments in a contemporary context with a look at future developments in this rapidly changing field of science and engineering.

Ideal for industrial engineers and scientists beginning careers in PV as well as graduate students undertaking PV research and high-level undergraduate students.

• Language: English
• Publisher: Wiley
• Release date: Jan 3, 2017
• ISBN: 9781118927489

Book preview

Table of Contents

Cover

Title Page

List of Contributors

Foreword

Acknowledgments

About the Companion Website

Part one: Introduction to Photovoltaics

1.1 Introduction

1.1.1 Introduction to Photovoltaic Solar Energy

1.1.2 Properties of Irradiance

1.1.3 Structure of the Book

List of Symbols

Constants

List of Acronyms

References

Part Two: Basic Functional Principles of Photovoltaics

2.1 Semiconductor Materials and their Properties

2.1.1 Semiconductor Materials

2.1.2 Crystalline Structures of Semiconductors

2.1.3 Energy Bands in Semiconductors

List of Symbols

List of Acronyms

References

2.2 Doping, Diffusion, and Defects in Solar Cells

2.2.1 Introduction

2.2.2 Silicon Wafer Fabrication

2.2.3 Ingot Formation

2.2.4 Doping and Diffusion

2.2.5 Defects in Silicon

List of Symbols

List of Acronyms

References

2.3 Absorption and Generation

2.3.1 Introduction

2.3.2 Generation of Electron Hole Pairs in Semiconductors

2.3.3 Absorption and Photogeneration

2.3.4 Absorption Coefficient for Direct and Indirect Bandgap Semiconductors

References

2.4 Recombination

2.4.1 Introduction

2.4.2 Radiative Recombination

2.4.3 Auger Recombination

2.4.4 Non-Radiative (Shockley-Read-Hall) Recombination

2.4.5 Surface, Interface and Grain Boundary Recombination

References

2.5 Carrier Transport

2.5.1 Introduction

2.5.2 Drift Current

2.5.3 Diffusion Current

2.5.4 Total Current

2.5.5 Quasi-Fermi Levels and Current

2.5.6 Continuity Equations

2.5.7 Minority Carrier Transport Equations

References

2.6 PN Junctions and theDiode Equation

2.6.1 Properties of a pn Homojunction

2.6.2 Ideal pn Diode in the Dark

2.6.3 Depletion Region Effects and the General Diode Equation

Acknowledgments

List of Symbols

List of Acronyms

References

Part Three: Crystalline Silicon Technologies

3.1 Silicon Materials

3.1.1 Introduction

3.1.2 Electrical Properties

3.1.3 Optical Properties

3.1.4 Conclusion

List of Symbols

List of Acronyms

References

3.2 Silicon Solar Cell Device Structures

3.2.1 Introduction

3.2.2 Solar Cell Optics

3.2.3 Minimizing Electron-Hole Recombination

3.2.4 Minimizing Electrical Losses

3.2.5 Screen-Printed Silicon Solar Cells

3.2.6 Selective Emitter Solar Cells

3.2.7 PERC and PERL Solar Cells

3.2.8 Switching to Phosphorus-Doped Substrates

3.2.9 N-Type Rear Emitter Silicon Solar Cells

3.2.10 N-type Front Emitter Silicon Solar Cell

3.2.11 Efficiency Improvements for Industrial Solar Cells

3.2.12 Conclusion

References

3.3 Interdigitated Back Contact Solar Cells

3.3.1 Introduction

3.3.2 Different Types of IBC Solar Cells

3.3.3 IBC Solar Cells for One-Sun Flat-Plate Modules

3.3.4 Conclusion

List of Symbols

List of Acronyms

References

3.4 Heterojunction Silicon Solar Cells

3.4.1 Basic Principles

3.4.2 a-Si:H/c-Si Cell Development

3.4.3 Key Issues in a-Si:H/c-Si Cells

3.4.4 Advantages Compared to c-Si Cells

List of Symbols

List of Acronyms

References

3.5 Surface Passivation and Emitter Recombination Parameters

3.5.1 Introduction

3.5.2 Surface Passivation Mechanisms

3.5.3 Commonly Used Surface Passivating Films

3.5.4 Conclusion

List of symbols

List of acronyms

References

3.6 Passivated Contacts

3.6.1 Introduction

3.6.2 Theory of Passivated Contacts

3.6.3 Experimentally Realized Passivated Contacts

3.6.4 Conclusion

List of Symbols

List of Acronyms

References

3.7 Light Management in Silicon Solar Cells

3.7.1 Introduction

3.7.2 Theory and Experiment

3.7.3 Front-Surface Reflection

3.7.4 Parasitic Absorption

3.7.5 Light Trapping

3.7.6 Conclusion

List of Symbols

List of Acronyms

References

3.8 Numerical Simulation of Crystalline Silicon Solar Cells

3.8.1 Introduction

3.8.2 Why Numerical Simulations?

3.8.3 Commonly Used Software for the Numerical Simulation of Si Solar Cells

3.8.4 General Simulation Approach

3.8.5 Detailed Numerical Simulation of an mc-Si Solar Cell

3.8.6 Conclusion

References

3.9 Advanced Concepts

3.9.1 Introduction

3.9.2 Near-Term Advanced Options

3.9.3 Longer-Term Advanced Options

3.9.4 Conclusion

List of Acronyms

References

Part Four: Chalcogenide Thin Film Solar Cells

4.1 Basics of Chalcogenide Thin Film Solar Cells

4.1.1 Introduction

4.1.2 The Electronic Structure of Thin Film Solar Cells

4.1.3 The Current-Voltage Characteristics of Thin Film Solar Cells

4.1.4 Conclusion

List of Symbols

List of Acronyms

References

4.2 Cu(In,Ga)Se2 and CdTe Absorber Materials and their Properties

4.2.1 Introduction

4.2.2 Structural Properties

4.2.3 Phase Diagram

4.2.4 Electronic Properties and Defects

4.2.5 Optical Properties and Alloys

List of Symbols

List of Acronyms

References

4.3 Contacts, Buffers, Substrates, and Interfaces

4.3.1 Introduction

4.3.2 Substrates

4.3.3 Back Contact

4.3.4 Front-Contact Layers

4.3.5 Conclusion

List of Acronyms

References

4.4 CIGS Module Design and Manufacturing

4.4.1 Introduction

4.4.2 Deposition Processes and Equipment

4.4.3 Module Fabrication

4.4.4 Cost and Materials

4.4.5 Conclusion and future considerations

List of Acronyms

References

Part Five: Thin Film Silicon-Based PV Technologies

5.1 Amorphous and Nanocrystalline Silicon Solar Cells

5.1.1 Introduction

5.1.2 Amorphous and Nano-Crystalline Solar Technology

5.1.3 Thin Poly-crystalline and Mono-crystalline Silicon on Glass

5.1.4 Perspectives for Thin Silicon Solar Technology

5.1.5 Conclusion

List of Symbols

References

5.2 Thin Crystalline Silicon Solar Cells on Glass

5.2.1 Introduction

5.2.2 Solar Cells Based on Liquid-Phase Crystallized Silicon on Glass

5.2.3 Cell Concepts for Thin Crystalline Silicon Absorbers

5.2.4 Future Outlook

5.2.5 Conclusion

Acknowledgments

List of Symbols and Acronyms

References

5.3 Light Management in Crystalline and Thin Film Silicon Solar Cells

5.3.1 Introduction

5.3.2 Light Scattering Interfaces

5.3.3 Parasitic Losses

5.3.4 Conclusion

List of Symbols

List of Acronyms

References

5.4 New Future Concepts

5.4.1 Introduction

5.4.2 Thin Film Silicon Triple-Junction Solar Cells

5.4.3 Thin Film Silicon Quadruple-Junction Solar Cells

5.4.4 Further Improvements in Thin Film Crystalline Silicon Solar Cells

5.4.5 Conclusion

List of Symbols

References

Part Six: Organic Photovoltaics

6.1 Solid-State Organic Photovoltaics

6.1.1 Introduction

6.1.2 Definition

6.1.3 Brief History

6.1.4 Organic Semiconductors

6.1.5 Processing of Organic Semiconductors

6.1.6 Physics of Organic Solar Cells

6.1.7 State-of-the-Art and Current Trends

6.1.8 Conclusion

Acknowledgments

Acronyms

References

6.2 Hybrid and Dye-Sensitized Solar Cells

6.2.1 Introduction

6.2.2 Current Status of Hybrid and Dye-Sensitized Solar Cell Performance

6.2.3 Hybrid Quantum Dot Solar Cells

6.2.4 Silicon-Organic Hybrid Solar Cells

6.2.5 Dye-Sensitized Solar Cells

6.2.6 Conclusion

References

6.3 Perovskite Solar Cells

6.3.1 Introduction

6.3.2 Organic-Inorganic Perovskites for Photovoltaics

6.3.3 Deposition Methods

6.3.4 Enabling Properties and Operation

6.3.5 Ongoing Challenges

6.3.6 Conclusion

References

6.4 Organic PV Module Design and Manufacturing

6.4.1 Introduction

6.4.2 Important Module Parameters

6.4.3 Wet Processing Technologies

6.4.4 Interconnections

6.4.5 Future Outlook

List of Acronyms

References

Part Seven: Characterization and Measurements Methods

7.1 Methods and Instruments for the Characterization of Solar Cells

7.1.1 Introduction

7.1.2 External Quantum Efficiency

7.1.3 Energy Conversion Efficiency

7.1.4 Spectral Mismatch

7.1.5 Conclusion

List of Symbols

List of Acronyms

References

7.2 Photoluminescence and Electroluminescence Characterization in Silicon Photovoltaics

7.2.1 Introduction

7.2.2 Theory

7.2.3 Applications

7.2.4 Luminescence Imaging

7.2.5 Conclusion

Acknowledgments

List of Symbols

List of Acronyms

References

7.3 Measurement of Carrier Lifetime, Surface Recombination Velocity, and Emitter Recombination Parameters

7.3.1 Introduction

7.3.2 Carrier Lifetime

7.3.3 Measurement of the Carrier Densities and Generation Rate

7.3.4 Calculation of the Effective Lifetime

7.3.5 Separation of the Surface Lifetime

7.3.6 Calculation of the Surface Recombination Velocity and Emitter Recombination Current

7.3.7 Conclusion

List of Symbols

List of Acronyms

References

7.4 In-situ Measurements, Process Control, and Defect Monitoring

7.4.1 Introduction

7.4.2 Monitoring of Vapor Phase Film Growth

7.4.3 Optical Properties

7.4.4 Electrical Behavior

7.4.5 Conclusion

List of Acronyms

References

7.5 PV Module Performance Testing and Standards

7.5.1 Introduction

7.5.2 Indoor Testing

7.5.3 Outdoor Testing

7.5.4 Sandia Photovoltaic Array Performance Model

7.5.5 Conclusion

List of Symbols

List of Acronyms

References

Part Eight: III-Vs and PV Concentrator Technologies

8.1 III-V Solar Cells – Materials, Multi-Junction Cells – Cell Design and Performance

8.1.1 Historical Overview and Background of III-V solar cells

8.1.2 Minimizing Optical and Electrical Losses in III-V Solar Cells

8.1.3 Monolithic III-V Multi-junction Cell Architectures

8.1.4 Conclusion

Acknowledgments

List of Acronyms

References

8.2 New and Future III-V Cells and Concepts

8.2.1 Introduction

8.2.2 Summary of Requirements

8.2.3 New and Future Cells and Concepts

8.2.4 Conclusion

List of Acronyms and Symbols

References

8.3 High Concentration PV Systems

8.3.1 Introduction

8.3.2 Optics

8.3.3 Trackers

8.3.4 Performance Evaluation and Fault Detection

8.3.5 Cost Optimization

8.3.6 Assembly and Reliability

8.3.7 Receiver Assembly and Thermal Management

8.3.8 Housing

8.3.9 Certification and Test Method Standards

8.3.10 Future Directions

List of Acronyms

References

8.4 Operation of CPV Power Plants

8.4.1 Introduction

8.4.2 Performance Models

8.4.3 Performance Standards

8.4.4 Prediction vs. Measurement

8.4.5 Conclusion

List of Acronyms

References

8.5 The Luminescent Solar Concentrator (LSC)

8.5.1 Introduction

8.5.2 Challenges for the Deployment of the LSC

8.5.3 The Future of the LSC

List of Symbols

List of Acronyms

References

Part Nine: Space Technologies

9.1 Materials, Cell Structures, and Radiation Effects

9.1.1 Introduction

9.1.2 Radiation Response Mechanisms

9.1.3 Effect of Radiation on Space Solar Cells

9.1.4 Effect of Radiation on Multijunction Space Solar Cells

9.1.5 Correlating Radiation Damage

9.1.6 Conclusion

List of Symbols and Units

References

9.2 Space PV Systems and Flight Demonstrations

9.2.1 Introduction

9.2.2 The Building Block of the Solar Array: the Cell with Interconnect and Cover Glass

9.2.3 System Considerations

9.2.4 Solar Array Interactions with the Space Environment

9.2.5 Space Solar Array Research and Development Trends

9.2.6 Conclusion

Acknowledgments

List of Acronyms

References

9.3 A Vision on Future Developments in Space Photovoltaics

9.3.1 Current Status and Near-Term Challenges/Opportunities

9.3.2 Near-Term Technologies to Address Challenges

9.3.3 Far-Term Power Needs and Technology Options

List of Symbols

List of Acronyms

References

Part Ten: PV Modules and Manufacturing

10.1 Manufacturing of Various PV Technologies

10.1.1 Introduction

10.1.2 Manufacturing of Screen-Printed p-Type Silicon Cells

10.1.3 Advanced p-Type Cell Technologies

10.1.4 Higher Efficiency n-Type Technologies

10.1.5 Conclusion

Acknowledgements

List of Abbreviations

References

10.2 Encapsulant Materials for PV Modules

10.2.1 Introduction

10.2.2 Types of Encapsulant Materials

10.2.3 Polymer Light Transmittance

10.2.4 UV Durability

10.2.5 Resistivity

10.2.6 Moisture Ingress Prevention

10.2.7 Conclusion

Acknowledgments

List of Symbols

List of Acronyms

References

10.3 Reliability and Durability of PV Modules

10.3.1 Introduction

10.3.2 PV Module Durability, Quality, and Reliability Issues

10.3.3 Strategy for Improving PV Reliability

10.3.4 Conclusion

Acknowledgments

References

10.4 Advanced Module Concepts

10.4.1 Introduction

10.4.2 Double-Glass Modules

10.4.3 Anti-Reflection Coated Glass

10.4.4 Half-cell Modules

10.4.5 Light Capturing Ribbon

10.4.6 Light Reflective Film

10.4.7 Smart Wire and Multi-Busbars

10.4.8 Smart PV Modules

10.4.9 Conclusion

List of Symbols

List of Acronyms

References

Part Eleven: PV Systems and Applications

11.1 Grid-Connected PV Systems

11.1.1 Introduction

11.1.2 Grid-Connected System Types

11.1.3 Performance

11.1.4 Safety and Fire Protection

11.1.5 Conclusion

Acknowledgments

List of Acronyms

References

11.2 Inverters, Power Optimizers, and Microinverters

11.2.1 Introduction

11.2.2 Power Conversion

11.2.3 DC Maximum Power Point Tracking

11.2.4 Inverter Efficiency

11.2.5 Auxiliary Functions

11.2.6 Conclusion

List of Symbols

List of Acronyms

References

11.3 Stand-Alone and Hybrid PV Systems

11.3.1 Introduction

11.3.2 Solar Pico Systems

11.3.3 Solar Home Systems

11.3.4 Hybrid PV Systems for Stand-Alone Applications

11.3.5 PV Diesel Mini-Grids

11.3.6 Battery Storage

11.3.7 Conclusion

References

11.4 PV System Monitoring and Characterization

11.4.1 Introduction

11.4.2 Monitoring Practice

11.4.3 Monitoring Examples

11.4.4 Conclusion

Acknowledgments

List of Symbols

List of Acronyms

References

11.5 Energy Prediction and System Modeling

11.5.1 Introduction

11.5.2 Irradiance and Weather Inputs

11.5.3 Plane of Array Irradiance

11.5.4 Shading, Soiling, Reflection, and Spectral Losses

11.5.5 Cell Temperature

11.5.6 Module IV Models

11.5.7 DC-DC Maximum Power Point Tracking and DC Losses

11.5.8 DC to AC Conversion

11.5.9 AC Losses

11.5.10 Modeling of Stand-Alone PV Systems

11.5.11 Conclusion

List of Symbols and Acronyms

References

11.6 Building Integrated Photovoltaics

11.6.1 Introduction

11.6.2 BAPV vs BIPV

11.6.3 BIPV Design

11.6.4 BIPV Building Aspects, Codes and Regulations

11.6.5 Outlook

List of Acronyms

References

11.7 Product Integrated Photovoltaics

11.7.1 Introduction: What Is Product Integrated Photovoltaics?

11.7.2 Application Areas of Product Integrated Photovoltaics

11.7.3 Selected Items for Product Integrated Photovoltaics

11.7.4 Conclusion

List of Acronym

References

Part Twelve: PV Deployment in Distribution Grids

12.1 PV Systems in Smart Energy Homes

12.1.1 Introduction

12.1.2 Technology

12.1.3 Matching Supply and Demand

12.1.4 New Energy Services

12.1.5 Results and Lessons Learned

12.1.6 Conclusion

List of Acronyms

References

12.2 New Future Solutions

12.2.1 Introduction

12.2.2 Insights from the JRC Smart Grid Inventory

12.2.3 Main Solutions Investigated by the Projects in the JRC Inventory

12.2.4 Conclusion

List of Acronyms

References

Part Thirteen: Supporting Methods and Tools

13.1 The Economics of PV Systems

13.1.1 Introduction

13.1.2 Levelized Cost of Electricity (LCOE)

13.1.3 PV System Cost

13.1.4 System Energy Production

13.1.5 Cost of Capital

13.1.6 System Life

13.1.7 Annual Operating Costs

13.1.8 PV LCOE and Grid Parity

13.1.9 Conclusion

List of Acronyms

References

13.2 People’s Involvement in Residential PV and their Experiences

13.2.1 Introduction

13.2.2 Residents Purchasing and Owning a PV System

13.2.3 Residents Commissioning a House Renovation

13.2.4 People Receiving a PV System

13.2.5 Owners Using a PV System

13.2.6 Citizens Participating in Collective Initiatives

13.2.7 Synthesis and Conclusion

References

13.3 Life Cycle Assessment of Photovoltaics

13.3.1 Introduction

13.3.2 Methodology

13.3.3 Cumulative Energy Demand (CED) during the Life of a PV System

13.3.4 Results

13.3.5 Conclusion

References

13.4 List of International Standards Related to PV

13.4.1 Introduction

13.4.2 IEC Standards Overview

13.4.3 Underwriters’ Laboratories (UL) Standards

13.4.4 The SEMI Standards

Acknowledgements

References

Index

End User License Agreement

List of Tables

Chapter 2.1

Table 2.1.1 Part of the Periodic Table of Elements related to semiconductors used in photovoltaic devices

Chapter 2.2

Table 2.2.1 Comparison of typical impurity level in metallurgical-grade silicon (MGS), solar-grade silicon (SoG-Si) and electronic-grade silicon (EGS) feedstock (values in ppm except as noted). Data from Sze (1983) and various silicon feedstock suppliers collected by the author

Table 2.2.2 Intrinsic diffusivity of boron and phosphorus in silicon (Sze, 1983)

Chapter 3.1

Table 3.1.1 Main electrical and optical properties of silicon

Chapter 3.3

Table 3.3.1 Recent performance achievements in IBC solar cell development

Chapter 3.5

Table 3.5.1 Analytical relations for Seff and J0s for n-type c-Si for certain boundary conditions. Sn0 and holes Sp0 are the fundamental surface recombination velocity for electrons and holes, q is the elementary charge, nd is the electron concentration at the position nearest to the surface where the energy bands are unaffected by the presence of fixed charge (nd = Nd + Δnd, with Δnd the injection level at position d), ni is the intrinsic carrier density, k is the Boltzmann constant, T is the temperature, Ɛsi is the permittivity of silicon, ND is the bulk doping density, and Qf is the fixed charge density

Table 3.5.2 Non-exhaustive summary of the experimentally obtained properties for the most commonly used dielectric films for passivating c-Si surfaces

Chapter 3.8

Table 3.8.1 Simulation software most commonly used for simulating crystalline Si solar cells

Chapter 4.1

Table 4.1.1 Comparison of solar cell parameters for thin film solar cells and crystalline Si solar cells

Chapter 4.2

Table 4.2.1 CuInSe2 and CdTe selected materials’ properties

Table 4.2.2 Silicon, CdTe and CuInSe2 associated denominations

Chapter 4.3

Table 4.3.1 Typical properties of substrate materials used for CIGS solar cells (Reinhard et al., 2013)

Table 4.3.2 Small-area Cu(In,Ga)Se2 based champion cells with alternative buffer layers which exhibit conversion efficiencies > 16 % in comparison to the world record CIGS cell with a CdS buffer: All denoted efficiencies refer to total-area values with anti-reflective coating if not stated otherwise. Typical cell area A is around 0.5 cm²

Chapter 5.1

Table 5.1.1 Best solar efficiencies for thin Si solar cells

Chapter 5.2

Table 5.2.1 Material properties of various thin crystalline silicon films of 2–10 µm thickness and published best open circuit voltages Voc and conversion efficiencies η of cell based on these absorbers

Chapter 6.2

Table 6.2.1 Current status of hybrid and dye-sensitized PV technologies: Most of confirmed cell, minimodule, and submodule efficiency are adopted from (Green, 2011, 2014, 2015a, 2015b) and measured under the AM 1.5 global spectrum (100 mW/cm²) at 25 °C. Note that efficiencies of Si-organic hybrid cells are reported to be measured under the one-sun condition (25 °C) but not confirmed yet

Chapter 6.4

Table 6.4.1 Benefits and challenges for roll-to-roll solution processing

Table 6.4.2 Comparing different major wet processing technologies

Chapter 7.1

Table 7.1.1 Classification parameters of solar simulators

Chapter 7.5

Table 7.5.1 International standards related to performance testing of PV modules

Table 7.5.2 Standard ratings for solar simulators per IEC 60904-9

Chapter 8.5

Table 8.5.1 Overview of typical luminophores and their advantages and disadvantages

Chapter 10.2

Table 10.2.1 Solar photon (300–1100 nm) weighted average optical density determined fromtransmittance measurements through polymer samples of various thickness (1.5–5.5 mm) laminated between two pieces of 3.18-mm-thick, Ce-doped, low-Fe glass (Kempe, 2010)

Table 10.2.2 Data taken from Reid et al. (2013) showing the variability in resistivity of a number of PV encapsulant materials

Chapter 10.3

Table 10.3.1 Failure mechanisms, related test methods, and example of current research needs

Chapter 11.1

Table 11.1.1 Design and operation factors impacting performance

Table 11.1.2 PV system grounding and protection methods

Chapter 11.3

Table 11.3.1 Comparison of different selected battery technologies (Vetter, 2014)

Chapter 11.4

Table 11.4.1 Examples of malfunctions (after Stettler, 2005)

Chapter 11.6

Table 11.6.1 BIPV categories, sub-categories and techniques.

Chapter 11.7

Table 11.7.1 Comparison of six PIPV products according to 100 users’ feedback after having used the products.

Chapter 13.1

Table 13.1.1 Simplified PV system costs, 2008, 2015 and 2025

Table 13.1.2 Project risks influencing financing costs

Chapter 13.2

Table 13.2.1 Use of financial metrics, more than one answer allowed (N = 360)

Chapter 13.4

Table 13.4.1 Active and Draft IEC standards and technical specifications

Table 13.4.2 UL standards

Table 13.4.3 SEMI standards and specifications

List of Illustrations

Chapter 1.1

Figure 1.1.1 Comparison of CO2-equivalent emissions of various energy technologies. Note the logarithmic y-scale.

Figure 1.1.2 Relation between color of (visible) light, wavelength and its energy.

Figure 1.1.3 Solar spectra: ASTM E-490 representing AM0 (black line), ASTM G173-03 representing AM1.5 (red line), and a measured spectrum (green line) showing the differences that can occur in reality. Data from ASTM and University of Twente, The Netherlands.

Figure 1.1.4 Scheme representing incident, refracted and reflected irradiance at the interface of two media

Chapter 2.1

Figure 2.1.1 (a) Simple cubic lattice; (b) Diamond lattice with tetrahedron bonds; (c) Face centered cubic lattice. Source: Courtesy of Boudewijn Elsinga (2015)

Figure 2.1.2 Energy band diagram at zero Kelvin and at 300 Kelvin

Figure 2.1.3 Energy band diagrams for a conductor, a semiconductor and an insulator

Figure 2.1.4 Energy-momentum diagrams for a semiconductor

Chapter 2.2

Figure 2.2.1 Solar-grade crystalline silicon feedstock loaded in a fused silica crucible ready for multi-crystalline ingot production.

Figure 2.2.2 Production facility of multi-crystalline silicon ingots.

Figure 2.2.3 Four bricks in a wire saw ready to be sliced into wafers.

Figure 2.2.4 Bricks of multi-crystalline silicon after wafer slicing in a wire saw.

Chapter 2.3

Figure 2.3.1 The absorption process in a semiconductor (the Beer-Lambert law)

Figure 2.3.2 The E-k diagram and absorption process for (a) the direct bandgap semiconductor; and (b) the indirect bandgap semiconductor

Figure 2.3.3 Plot of bandgaps and lattice constants for a number of semiconductor. Circles indicate direct binary materials and triangles indirect binary materials. The solid, dashed and dotted lines indicate if the ternary bandgap is direct (Γ) or indirect (X, L)

Figure 2.3.4 Plot of the absorption coefficient for a number of direct (GaAs, InGaP2) and indirect (Ge, Si) semiconductors

Chapter 2.4

Figure 2.4.1 The three basic types of recombination processes: (a) radiative band-to-band; (b) non-radiative Auger; and (c) non-radiative recombination centers (traps)

Figure 2.4.2 Electron and hole capture at the surface of a semiconductor

Chapter 2.5

Figure 2.5.1 (a) Random electron scatter and drift velocity due to an electric field; and (b) drift current due to both electrons and holes in a semiconductor of cross-section area A

Figure 2.5.2 Diffusion currents due to the concentration gradients of holes and of electrons

Figure 2.5.3 Illustration of the concept leading to the continuity equation

Chapter 2.6

Figure 2.6.1 A pn junction band diagram showing the Fermi level, depletion region and built-in voltage

Figure 2.6.2 Plots of (a) charge density; (b) electric field; and (c) potential across a pn junction

Figure 2.6.3 A pn junction diode under an external bias Va

Figure 2.6.4 Examples of dark current density versus voltage (JV) curves showing (a) rectifying behavior when plotted on a linear scale; and (b) reverse saturation current and diode ideality factor when plotted on a logarithmic scale

Chapter 3.1

Figure 3.1.1 Effective intrinsic carrier density ni,eff as a function of temperature and doping level and type; lines are calculated using the models and assumptions discussed in the text; the symbol marks the measured value of ni in.

Figure 3.1.2 Minority electron (a) and hole (b) mobility as a function of doping density comparing Klaassen’s model (solid line: minority mobility, dashed line: majority mobility) with various measurements (symbols).

Figure 3.1.3 Absorption coefficient αBB of silicon for several temperatures; dashed lines: calculated from (Green, 2008); solid lines: data from (Nguyen et al., 2014b); though differences between the different data sets appear minor, they are significant for luminescence spectroscopy.

Chapter 3.2

Figure 3.2.1 Schematic of a typical solar cell

Figure 3.2.2 Effect of a textured surface on the reflectivity of silicon

Figure 3.2.3 A typical process of a screen-printed silicon solar cell.

Figure 3.2.4 Screen-printed silicon solar cell

Figure 3.2.5 Screen printed silicon solar cell with selective emitter

Figure 3.2.6 PERC solar cell.

Figure 3.2.7 PERL solar cell.

Figure 3.2.8 n-type rear emitter silicon solar cell

Figure 3.2.9 n-type front emitter silicon solar cell

Chapter 3.3

Figure 3.3.1 Interdigitated back contact solar cell.

Figure 3.3.2 Current flow and potential in an IBC solar cell with 200 μm half-pitch under 50 suns (5 W/cm²). (a) Minority carrier current flow Jp and quasi-Fermi level Φp. (b) Total current flow JT=Jp + Jn and potential Ψ.

Figure 3.3.3 (a) FSF, (b) FFE and (c) PC solar cell designs

Figure 3.3.4 Structure of PC solar cell for high-concentration CPV application.

Chapter 3.4

Figure 3.4.1 Energy band diagrams for a heterojunction. (a) Two separated semiconductors, with a wide bandgap n-type semiconductor on the left and a narrow band gap p-type semiconductor on the right. (b) Energy levels after bringing the materials into contact and reaching an equilibrium state. The vacuum level remains continuous, while the conduction and valence band are discontinuous.

Figure 3.4.2 Energy band diagrams for (a) the separate materials p-type a-Si:H and n-type c-Si; and (b) the a-Si:H/c-Si heterojunction. Black and grey dots represent electrons and holes, respectively. The circle indicates the carrier (hole) transport through the energy barrier at the interface.

Figure 3.4.3 Schematic structure of heterojunction a-Si:H/c-Si solar cells. (a) basic structure with transparent conductive oxide and metal as top and back contact; (b) idem, with intrinsic a-Si:H layer sandwiched between p a-Si:H and n c-Si; (c) idem, with textured interfaces and back-surface field layer of n a-Si:H, (d) idem, with additional i a-Si:H. Note, drawings are not to scale

Chapter 3.5

Figure 3.5.1 Simulated solar cell for a high-efficiency silicon wafer solar cell as a function of the solar cell thickness for various values of the effective surface recombination velocity at the rear side of the solar cell. The values that can be obtained by the standard aluminum back surface field are in the range of 200–600 cm/s while more advanced solar cell architectures can achieve values well below 100 cm/s. These simulations were conducted in the software package PC1D.

Figure 3.5.2 Schematic illustration of (a) chemical passivation; and (b) field-effect passivation

Figure 3.5.3 (a) Active boron doping depth profile as determined by electrochemical capacitance-voltage (ECV) profiling; and (b) resulting simulated J0e value as a function of Sn0 for various values of Qf (in unit of elementary charges). The sheet resistance of the boron emitter was determined to be 30 Ω/◽ by means of a four-point-probe measurement. The simulations were performed by Fajun Ma from the Solar Energy Institute of Singapore (SERIS) in the software package Sentaurus of Synopsys, assuming only intrinsic recombination in the emitter and an SRH recombination at the surface.

Chapter 3.6

Figure 3.6.1 Simulated dark saturation current density for a phosphorus doped surface either passivated with SiO2 (surface recombination velocity, SRV, is a function of NA after (Altermatt, 2011)) or contacted with metal (SRV = 10⁷ cm/s) as a function of the surface doping concentration. Low saturation current densities can be achieved with passivated lowly doped surfaces. The metallization of such lowly doped surfaces leads to very high J0 values. The J0 can be decreased by increasing the surface doping concentration. However, values of at least one order of magnitude higher than the passivated areas are still present. The simulations were conducted using the software package EDNA (McIntosh and Altermatt, 2015)

Figure 3.6.2 Schematic silicon band diagram with different electron and hole contact systems, leading to either an ideal solar cell (a) or recombination or transport limited solar cells (b) and (c) respectively

Figure 3.6.3 Band diagram of TCO/a Si:H(p)/c-Si structure (not to scale)

Figure 3.6.4 Band diagram of hole SIS contact (left) and MIS contact (right)

Figure 3.6.5 Calculated internal open circuit voltage (Vint ) and external open circuit voltage (Vext) as a function of the work function of the contact material for different interface recombination velocities

Figure 3.6.6 TEM image of a cross-section of a TOPCon contact. Between the crystalline Si absorber and the amorphous/nanocrystalline silicon layer, the SiOx tunnel layer is clearly seen

Chapter 3.7

Figure 3.7.1 Schematic depiction of the path taken by visible and infrared light in a silicon solar cell and penetration depth of red and infrared light in a silicon wafer.

Figure 3.7.2 (a) External quantum efficiency and 1 − reflection spectra for a representative silicon heterojunction solar cell on a 110-µm-thick wafer. (b) Measured and corrected (free of parasitic absorption) external quantum efficiency of the same cell, and light-trapping limits to which the corrected spectra may be compared

Chapter 3.8

Figure 3.8.1 General simulation approach

Figure 3.8.2 (a) Simulated recombination currents; and (b) simulated series resistivity of an mc-Si solar cell, under one-sun standard conditions.

Chapter 3.9

Figure 3.9.1 Four advanced silicon cell technologies: (a) Metal Wrap Through (MWT); (b) Passivated Emitter and Rear Cell (PERC); (c) Interdigitated Back Junction (IBJ); (d) Heterojunction Cell (HJT).

Figure 3.9.2 (a) Share of new silicon-based manufacturing capacity from different cell approaches. (b) Expected total market share of different silicon cell technologies.

Figure 3.9.3 Limiting energy conversion efficiency under the AM1.5G spectrum for tandem stacks both with silicon as the bottom cell and with an unrestricted choice of bottom cell material

Chapter 4.1

Figure 4.1.1 (a) Physical structure of chalcogenide solar cells; (b) electronic band diagram of a Cu(InGa)Se2 cell

Chapter 4.2

Figure 4.2.1 (a) FCC structure of a Si crystal with two identical atoms basis; (b) CdTe structure derived from the Si structure by replacing identical atoms basis by two different atoms; (c) CuInSe2 structure derived from the CdTe structure by doubling the CdTe structure and replacing the cations by two different cations.

Figure 4.2.2 (a) CdTe phase diagram. Source: after Jianrong, Silk, Watson and Bryant (1995); (b) quasi-binary phase diagram of CuInSe2 along the In2Se3-Cu2Se tie-line.

Figure 4.2.3 Main theoretical electronic levels of defects: (a) in CdTe; and (b) CuInSe2.

Figure 4.2.4 Summary of the lattice constants versus band gap for some II-VI materials

Figure 4.2.5 Summary of the lattice constants versus band gap for some I-III-VI2 materials

Chapter 4.3

Figure 4.3.1 Scheme of different CIGS cells stacks on glass/Mo substrates with alternative buffer layer systems compared with the commonly used CdS/i-ZnO.

Chapter 4.4

Figure 4.4.1 Large area CIGS-based modules manufactured in 2014 by Solar Frontier on a glass substrate (left) and Global Solar Energy on flexible foil (right)

Figure 4.4.2 Process sequence for manufacturing CIGS modules on a glass substrate

Figure 4.4.3 Schematic for typical monolithic integration including P1, P2, and P3 scribes

Figure 4.4.4 Approaches for interconnection of CIGS cells using foil substrates with (a) a shingle overlapping connection or (b) stringing and tabbing connection

Chapter 5.1

Figure 5.1.1 Schematics of four different device configurations.

Figure 5.1.2 Independently certified efficiencies of different photovoltaic technologies, plotted with respect to the cell or module size.

Figure 5.1.3 Examples of thin film silicon modules in the built environment. (Left top and bottom) semi-transparent a-Si:H modules. (Right top) Terracotta orange modules based on thin film Si. (Bottom right). Old building clad with thin film Si module

Chapter 5.2

Figure 5.2.1 Predicted c-Si wafer thicknesses in solar cell production within the next decade based on SEMI’s technology roadmap for photovoltaic (SEMI Solar, 2014) in comparison with targeted thickness range for thin crystalline silicon on glass technology

Figure 5.2.2 Scheme of the liquid-phase crystallization process of a silicon precursor layer on glass: (a) coated with an intermediate layer (IL) stack; and (b) the resulting grain structure of the LPC-Si absorber layer

Figure 5.2.3 Scheme of the fabrication process for LPC-Si-based thin-film solar cells: deposition of IL and absorber layers (Section 5.2.2.2), crystallization (Section 5.2.2.1) and cell contacting (Section 5.2.3)

Figure 5.2.4 Schematic representation of an n-type IBC hetero-junction solar cell-based thin crystalline silicon absorbers on glass

Chapter 5.3

Figure 5.3.1 Absorption in amorphous (squares) and microcrystalline silicon films (circles). Full symbols denote , the single pass absorption with zero reflection at the front and ideal transmission at the back, dashed lines represent the approximation αd. Open symbols show the enhancement according to eq. (1) with scattering and perfect back-reflector, dotted lines illustrate path enhancement by 4n². The images to the right show surface textures of 5 μm thick ZnO films used in microcrystalline solar cells before (upper) and after (lower) surface treatment,

Figure 5.3.2 The left panel shows the angular resolved scattering of the upper ZnO texture in Figure 1; symbols denote scattering into air measured with λ = 543 nm, the thick line denotes data of a Fourier model on the basis of the atomic force microscopy surface profile, the thin line represents a projection of scattering into silicon. The dashed circle illustrates the Lambertian cosine dependence. The right panel shows the same data after weighting with the spherical Jacobian

Figure 5.3.3 Photocurrent of n-i-p cells on textured silver electrode with varying buffer layer thickness (left panel). The right panel shows the underlying external quantum efficiency (EQE) and the EQE after correction for reflected light.

Chapter 5.4

Figure 5.4.1 Efficiency versus thickness for c-Si solar cells under one-sun illumination at 25°C. The solid lines represent the efficiency for a cell made of 1 Ω·cm p-type Si and undoped Si, taking radiative and Auger recombination, as well as photon recycling (PR) into account. The additional curves show cells constrained by either only Auger recombination or by Auger and radiative recombination. Both curves were calculated without taking PR into account and, thus, represent an upper limit assuming complete photon recycling and a lower limit assuming no photon recycling, respectively. Additionally, the curves are also shown for 1 Ω·cm p-type Si calculated with the modeling parameters used by Kerr et al. (2003). The cross symbols are the corresponding data points digitized from Kerr et al. (2003).

Chapter 6.1

Figure 6.1.1 (a) Cross-sectional schematic representation of an organic solar cell; (b) Corresponding energy level diagram of the solar cell under illumination. WH: high work function of the hole-collecting interlayer; WL: low work function of the electron- collecting layer. LUMOA: lowest unoccupied molecular orbital energy of the acceptor material in the organic absorber; HOMOD highest occupied molecular orbital energy of the donor in the absorber; Fn quasi-Fermi level energy for electrons; Fp quasi-Fermi level energy for holes

Figure 6.1.2 Schematics of the π electrons (πe) in the pz orbitals on each carbon atom and their delocalization over the conjugated polymer chain due to electronic coupling between neighboring carbon atoms.

Figure 6.1.3 Energy-level diagram of organic semiconductors (center) showing the relative position of the HOMO and LUMO bands with respect to the vacuum level used as reference. Selected examples of the chemical structure of electron-donor like materials used as hole transport materials in organic photovoltaics are shown on the left. Such materials have a low ionization energy (IE). Selected examples of the chemical structure of electron-acceptor-like materials used as electron transport materials are shown on the right. Such materials have a large electron affinity (EA). P3HT: poly(3-hexylthiophene); PC60BM: 6,6-phenyl-C 61-butyric acid methyl ester; ICBA: indene-C 60 bisadduct

Chapter 6.2

Figure 6.2.1 The bandgap-voltage offset (Woc) under the open-circuit condition as a function of QD bandgap (Eg) in different configuration of QD solar cells; (1) PbS QDs/metal Schottky junction ( ) (Yoon et al., 2013); (2) QD heterojunction devices based on n-type wide bandgap semiconductors for ( : ZnO/PbS, : TiO2/PbS, : CdS/PbS, +: CdSexTe1-x/ZnO, ×: CdTe/ZnO and : CdSe/CdTe) (Luther et al., 2010; Brown et al., 2011; Gao et al., 2011; Jasieniak et al., 2011; MacDonald et al., 2012; Bhandari et al., 2013; Chang et al., 2013; Hyun et al., 2013; Chuang et al., 2014; Townsend et al., 2014; Yoon et al., 2014); and (3) p-n homojunction using n-type PbS NCs ( ) (Tang et al., 2012)

Figure 6.2.2 Schematic of (a) a front junction PEDOT:PSS/n-Si heterojunction and (b) a back junction n-Si/PEDOT:PSS heterojunction solar cell. (c) Stability of a front junction PEDTO:PSS/n-Si heterojunction solar cell as a function of storage time in darkness. and (d) Achievable Voc in the front-junction organic-Si heterojunction cells with phosphorus-doped BSF for the limiting Jsc of 34.7 mA/cm² and the saturation current density of P-diffused BSF (J0,b) of 1250 fA/cm².

Figure 6.2.3 (a) Schematic and (b) energy level and operation of dye-sensitized solar cells (c) Open-circuit voltage as a function of absorption onset and loss-in-potential with radiative limits. The literature values in the absorption onsets and the loss-in-potentials are shown for the ruthenium dye (CYC-B11)/iodide redox couple (C.-Y. Chen et al., 2009), the N719 dye/iodide redox couple (Nazeeruddin et al., 2005), the black dye N749/iodide redox couple (Nazeeruddin et al., 2001), the co-sensitized donor–pi–acceptor dye (YD2-o-C8 and Y123)/cobalt redox couple (Yella et al., 2011), the SM371/Co(II/III) (Mathew et al., 2014), the SM315/Co(II/III) (Mathew et al., 2014), and the Y123 dye/hole conductor spiro-OMeTAD (Burschka et al., 2011).

Chapter 6.3

Figure 6.3.1 Perovskite ABX3 crystal structure where typically A = CH3NH3+, B = Pb²+ and X = I−, Br−, Cl−, or mixtures thereof.

Figure 6.3.2 Photographs of FAPbIyBr3-y perovskite films with y increasing from 0 to 1 from left to right, and corresponding absorption spectra.

Figure 6.3.3 J-V curves of the highest performing device to date consisting of FTO-Glass/bl-TiO2/mp-TiO2/perovskite/PTAA/Au measured under standard AM 1.5G illumination, giving a power conversion efficiency of 20.2%.

Figure 6.3.4 Record efficiencies of various established PV technologies over the years. Closed symbols are published laboratory results, open symbols represent certified efficiency values (NREL, 2016).

Figure 6.3.5 Open-circuit voltage (Voc) versus optical band gap for the best-in-class solar cells for most current and emerging solar technologies as extracted from Green et al (Green et al., 2015). The optical band gaps have been estimated by taking the onset of the incident photon to converted electron (IPCE) for all technologies (Snaith, 2013).

Figure 6.3.6 Effective absorption coefficient of a CH3NH3PbI3 perovskite thin film compared with other typical PV technologies. The slopes of the Urbach tail are displayed on the plot (De Wolf et al., 2014).

Figure 6.3.7 Time-resolved PL decays for MAPbI3-xClx thin films without (PMMA) and with n-type (PCBM) or p-type (Spiro-OMeTAD) quenching layers (Stranks et al., 2013). The mono-exponential lifetime τ is shown for the PMMA sample.

Figure 6.3.8 Illustration of the charge generation processes in a planar heterojunction perovskite solar cell (Stranks and Snaith, 2015).

Figure 6.3.9 IPCE fraction for the Sn-based perovskite solar cells with a range of different halides to tune the bandgap (Hao et al., 2014).

Figure 6.3.10 Forward bias to short circuit (FB-SC) and short circuit to forward bias (SC-FB) J-V curves measured under AM1.5 simulated sun light for a perovskite solar cell fabricated with a 400 nm thick mesoporous alumina film. Inset: Photocurrent density and power conversion efficiency as a function of time for the same cell held close to 0.75 V forward bias (Snaith et al., 2014).

Figure 6.3.11 Indoor heat stress test of a triple-layer perovskite solar cell. The device was encapsulated and kept for 3 months in a normal oven filled with ambient air at ~85°C and removed periodically to measure J-V curves under full solar AM1.5 light at ambient temperature (Li et al., 2015).

Figure 6.3.12 Photographs showing non-encapsulated MAPbI3 and FAPbI3 samples before and during heating on a hot plate at 150°C for 60 minutes in air (Stranks and Snaith, 2015).

Chapter 6.4

Figure 6.4.1 HeliaFilm™ encapsulation output and vision on low-cost solar cell in BIPV ©Heliatek.

Figure 6.4.2 Two examples of free-form OPV modules; left, the Solarte garden lamp by Belectric OPV and, right, the world’s first polychrome solar module by DisaSolar.

Figure 6.4.3 Schematic representations of (a) spray coating; (b) slot-die coating; (c) inkjet printing; (d) screen printing; and (e) rotary screen printing.

Figure 6.4.4 Schematic representations of interconnections using only wet processing techniques (left) and P1, P2, P3 in-process scribing (right)

Figure 6.4.5 Schematic representations of back-end interconnections by combining P1,P2,P3 scribes and isolating and conductive inks

Chapter 7.1

Figure 7.1.1 Schematic representation of a solar cell QE measurement configuration

Figure 7.1.2 Example of silicon solar cell QE measurement result (measured at 25 °C)

Figure 7.1.3 LED and sunlight irradiance spectra (equal energy content).

Figure 7.1.4 Solar cell I-V curve conventions: (a) Conventional diode I-V curve; (b) Diode I-V curve with current polarity inverted; (c) Inverted diode curve shifted for current generation; (d) Power curve added.

Figure 7.1.5 Solar cell diode model

Figure 7.1.6 Solar cell I-V curves with LED illumination (a) blue LED, (b) infrared LED, (c) simulated AM1.5G sunlight.

Figure 7.1.7 Solar cell measurement circuit

Figure 7.1.8 Solar cell ribbon simulator probing bars

Figure 7.1.9 Solar cell I-V curve used to determine series resistance.

Chapter 7.2

Figure 7.2.1 Room temperature band-to-band photoluminescence spectrum from a crystalline silicon wafer on linear (dotted line, left-hand scale) and on semi-logarithmic (solid line, right-hand scale). T = 291 K, data from (Trupke et al., 2003)

Figure 7.2.2 Spectral absorption coefficient of crystalline silicon for various temperatures. Data from PL (dotted lines) and from conventional optical transmission (solid lines) for various temperatures (given in the figure caption). The top curve represents absorption coefficient data from spectral response measurements at room temperature, which show an excellent match with data from PL

Figure 7.2.3 Bulk lifetime image of the side facet of a 6-inch, 23 cm high multicrystalline silicon brick prior to wafer slicing obtained using the PL intensity ratio method. The darkness scale represents the lifetime in microseconds, the right-hand side represents the top of the ingot.

Figure 7.2.4 PL image of an as-cut high performance multicrystalline silicon wafer, measured on a BT Imaging iLS-W2 automated inline PL imaging system (left) and results of automated image processing (right) showing shaded overlays for areas of high impurity concentration (light) and for the location of structural defects (shaded).

Figure 7.2.5 Series resistance image on a multicrystalline silicon solar cell measured using the method by Kampwerth (Kampwerth et al., 2008). The darkness scale gives the local series resistance in absolute units of Ω cm².

Figure 7.2.6 Electroluminescence images of industrial silicon modules showing (a) a large number of cracks as often induced by poor mechanical handling of fully assembled modules and (b) a module with one inactive string (i.e. two columns of inactive cells), as caused by a shunted by-pass diode or by one cell in the string being completely disconnected. Image data courtesy of Trina Solar

Chapter 7.3

Figure 7.3.1 Breakdown of the lifetime values and associated sections

Figure 7.3.2 Schematic arrangement of a photoconductance or photoluminescence setup

Figure 7.3.3 Typical exponential decay of the minority carrier decay Δn(t) after a transient generation G(t) at time t = 0

Figure 7.3.4 Graphic presentation of the inverse effective lifetime 1/τeff vs the inverse wafer thickness W. The inverse bulk lifetime 1/τb can be identified by the interception with the ordinate, leaving the inverse surface lifetime 1/τS

Chapter 7.4

Figure 7.4.1 A compact portable optical pyrometer

Figure 7.4.2 A simple quadrupole mass spectrometer such as this could be used to measure fluxes of atoms in a thin film deposition instrument

Figure 7.4.3 A schematic of the apparatus for an x-ray fluorescence system for monitoring film growth. Heating units are incorporated into the two units to prevent adsorption of species from the vapour phase.

Figure 7.4.4 Module-scale spectroscopic mapping tool under development as In-line SE by J.A. Woolam Co.

Figure 7.4.5 An optical bench and cryostat set up for measuring photoluminescence.

Chapter 7.5

Figure 7.5.1 Module temperature calculated using the Sandia Photovoltaic Array Performance Model for four array configurations at an ambient temperature of 20°C and a wind speed of 1 m/s.

Figure 7.5.2 Spectral irradiance of a xenon arc filtered to approximate the AM1.5G spectrum (IEC 60904-7, 2011). The magnitude of the xenon arc has been scaled to match the photon flux of AM1.5G from 280 nm to 1200 nm.

Figure 7.5.3 Predicted daily module short-circuit charge densities under clear sky conditions (solid lines) for various module designs. The symbols indicate values obtained by replacing the predicted spectrum with (normalized) reference spectra (AM1.5D for the III-V module, AM1.5G for the others). (Module charge density is the sum of the current per unit area over time for each day. This metric is used as an expedient parameter to increase the visual separation between the module types with similar current outputs.)

Figure 7.5.4 Modeled spectrum using TMY3 data (TMY3 database, available online) for Albuquerque, NM, USA and SMARTS Latitude-tilt global irradiance incident with the highest and lowest annual values for precipitable water vapor (PWV) in the atmosphere in Albuquerque are shown. Under the more arid conditions (PWV = 0.2 cm), irradiance in the range 280–4000 nm rises by 11%, whereas the irradiance below 1200 nm (near the Si band edge) rises by 7% and that below 880 nm (near the CdTe band edge) rises by only 2%.

Chapter 8.1

Figure 8.1.1 Schematic illustration of a GaAs heterostructure solar cell with n-GaAs base, p-GaAs emitter and p-AlGaAs front surface passivation layer also called the window layer

Figure 8.1.2 Lattice constant for arsenides, phosphides and antimonides versus the bandgap energy. The spectral irradiance of the AM0 solar spectrum is displayed as a reference and shows the important wavelength range which is covered by the III-V compounds

Figure 8.1.3 Increase of the thermodynamic efficiency limit for multi-junction solar cells, assuming that ideal bandgap combinations are used. Theoretical limits are given for both, one-sun AM1.5g and 500 suns AM1.5d conditions. Experimental values (stars) refer to the highest published 1-sun and concentrator cell performances (Chiu et al., 2013; Essig et al., 2011; Green, et al., 2015). Concentration ratios may vary between 300–600 suns. Theoretical calculations have been performed with the program EtaOpt (Létay and Bett, 2001)

Figure 8.1.4 Four-junction solar cell architectures close to the optimum bandgap combination of 1.9 eV, 1.4 eV, 1.0 eV and 0.5 eV. Metamorphic growth or wafer bonding is used to overcome differences in the lattice-constant of the III-V compounds

Chapter 8.2

Figure 8.2.1 Nano-scale self-assembled InGaAs/GaAs QDs with a density of 400 µm−2. The QDEC® heterostructure has many such layers incorporated in its middle subcell for bandgap engineering of its absorption

Figure 8.2.2 Heterostructure of Azastra’s phototransducer. Tunnel junctions (TJs) are used to interconnect multiple GaAs base segments (pn-GaAs). The thickness of each p-GaAs base region is designed to obtain photocurrent matching of all the base segments. The total thickness of all the base segments allows the absorption of substantially all of the input light.

Figure 8.2.3 (a) I-V plots of a packaged phototransducer at 3 different input powers for an optical input at 835 nm. (b) Measured phototransducer efficiency for input powers of 0.01 W (lower curves), 0.38 W (middle) and 1.15 W (higher curves). The maximum conversion efficiency occurs near 5 V and increases with the input power from about 60% at 0.01 W to 74.8% at 1.15 W.

Figure 8.2.4 Illustration of a through-semiconductor-via CPV cell design where instead of top surface gridlines and busbars, vias are etched through the heterostructure and the substrate to extract the front surface photocurrent via the backside, according to Richard et al. (2015)

Chapter 8.3

Figure 8.3.1 Relative power density produced by a two-dimensional tracking CPV module (30% efficiency) and a horizontal Si module (20% efficiency), on the summer solstice in Ottawa, Canada. The CPV module is capable of harvesting nearly twice the energy of the Si module

Figure 8.3.2 Two-axis tracker systems using (a) Fresnel-type modules by OPEL Solar Inc. in Ottawa, Canada, and (b) waveguiding optics by Morgan Solar Inc. in California, USA

Figure 8.3.3 Concentrator designs with different optical trains: (a) Fresnel lens, (b) Cassegrain primary reflectors, and (c) waveguiding designs

Figure 8.3.4 Illustration of normalized power as a function of incidence angle, depicting the acceptance half-angle, θa, as defined at 90% of maximum power

Figure 8.3.5 Schematic diagrams of popular CPV module and tracker architectures: (a) azimuth-elevation tracker (b) tilt and roll tracker

Figure 8.3.6 Global learning curve (log/log relationship between system price and cumulative deployment each year) for concentrated photovoltaic (CPV), concentrated solar (thermal) power (CSP), and flat-panel photovoltaic (PV) systems. Inset: The learning rate (proportional price reduction with doubling of volume) for each technology.

Chapter 8.4

Figure 8.4.1 A Suncore CPV installation in western China

Figure 8.4.2 Schematic of a notional point-focus CPV module and array. Design specifics vary, but larger modules and an array area of around 100 m² are optimized for rapid, mechanized field installation.

Figure 8.4.3 Some of the efficiency changes involved in moving from laboratory conditions to outdoor operation, as predicted for Albuquerque, USA, using the model described below.

Figure 8.4.4 Available irradiance for various fixed rack and tracking configurations. The projected electrical load from the California Independent System Operator (CAISO) is shown for reference.

Figure 8.4.5 Comparison of test conditions specified in IEC 61853 and operating conditions derived for Albuquerque, USA, Boston, USA, and Solar Village, Saudi Arabia. The cell temperature was determined using the Sandia Photovoltaic Array Performance Model (King et al., 2011) for DNI incident on a 22x linear concentrator. Note that STC conditions (1000 W/m², 25°C, outlined) are not encountered in operation at any of the three sites.

Figure 8.4.6 Hour-by-hour AC efficiency of a simulated CPV array (𝜂STC = 33%) in Albuquerque, USA. Corrections have been made for: temperature, irradiance, spectrum, soiling, and inverter efficiency. The prediction near sunrise and sunset can be distinguished as the lower-efficiency points that fall off on either side of the summer solstice

Figure 8.4.7 Predicted vs. measured cumulative energy for a 38-kWAC-PTC Amonix 7500 array deployed in Las Vegas, USA in 2009. After 3.5 years of operation, the cumulative energy differed from the prediction by less than 1%.

Figure 8.4.8 Sensitivity analysis of daily energy density (symbols) and energy yield (lines) for a 500x CPV system in Albuquerque, NM, USA. The result for TMY3 inputs is compared against cases where the temperature and spectrum are held constant. Cell temperature is assumed to be 40°C above the ambient. Energy yield is calculated based on peak power at CSTC (25°C, 1000 W/m²).

Chapter 8.5

Figure 8.5.1 Main loss mechanisms of luminescent solar concentrators. (1) Reflected incident light; (2) non-unity quantum yield; (3) incomplete absorption; (4) re-absorption events; (5) emission outside the capture cone; (6) absorption by matrix; (7) spectral mismatch with PV cell. Inset photograph: Four LSCs exposed to UV light from above.

Figure 8.5.2 Calculated emission profile of dichroic dye ensemble oriented perpendicular to the plane of the lightguide (homeotropic) illuminated from above.

Figure 8.5.3 Photographs of the Palais des Congrès, Montreal, Canada.

Chapter 9.1

Figure 9.1.1 A schematic representation of the effects that radiation-induced defect levels can have on current transport in a solar cell.

Figure 9.1.2 The radiation response of single-junction crystalline semiconductor solar cell technologies that have been developed for space use.

Figure 9.1.3 The degradation in QE of an InP solar cell due to 3 MeV proton irradiation. The particle fluence is given in the legend in units of cm−2. The long wavelength response degrades due to diffusion length degradation.

Figure 9.1.4 Minority carrier diffusion length data determined from analysis of QE data as a function of particle fluence (Figure 9.1.3). The line represents a linear regression of the data from which the diffusion length damage coefficient, KL, can be determined according to Equation (9.1.1).

Figure 9.1.5 Dark current data measured in the InP solar cell from the preceding figures. The proton irradiation causes an increase in the dark current. Analysis of these data shows that this increase is due to an increased diffusion current brought on by radiation-induced recombination/generation centers.

Figure 9.1.6 Quantum efficiency measurements made on a triple-junction InGaP2/GaAs/Ge solar cell before and after irradiation with 1 MeV electrons to a fluence of 1×10¹⁵ cm−2. The GaAs subcell (middle cell) is seen to degrade most rapidly of the three.

Figure 9.1.7 Calculated NIEL values for protons in the materials comprising the triple-junction InGaP2/GaAs/Ge solar cell.

Figure 9.1.8 A plot showing the relationship between the NIEL and diffusion damage coefficients for Si.

Figure 9.1.9 A plot showing the degradation of GaAs solar cells under electron and proton irradiation at a wide range of energies. When plotted as a function of Dd, the data collapse to a single, characteristic curve.

Figure 9.1.10 A plot showing the degradation of 3J InGaP/GaAs/Ge solar cells under electron and proton irradiation at a wide range of energies. As with the single-junction GaAs data in Figure 9.1.9, when plotted as a function of Dd, the data collapse to a single, characteristic curve.

Chapter 9.2

Figure 9.2.1 Photograph of secondary arc damage (Ferguson and Hillard, 2003).

Figure 9.2.2 Deployment of one of two solar arrays after it has been integrated into the Global Precipitation Mission (GPM) Core spacecraft, launched in 2014.

Figure 9.2.3 Manufactured examples of 2- and 4-meter diameter UltraFlex™ arrays (background) and a 10-meter MegaFlex™ array (foreground).

Figure 9.2.4 An illustration of the hybrid solar array, proposed by Baghdasarian (1998) showing two ridge panels (44 and 56) and five lateral panels

Figure 9.2.5 ROSA Solar Array and Deployment Sequence.

Chapter 9.3

Figure 9.3.1 Dawn solar array.

Figure 9.3.2 Cumulative cost for space solar panel assembly, starting with cells on the left and ending with full panels on the right

Chapter 10.1

Figure 10.1.1 Manufacturing sequence for screen-printed p-type silicon solar cells

Figure 10.1.2 A screen-printed silicon solar cell manufacturing facility showing multiple production lines.

Figure 10.1.3 Tube furnace showing a quartz boat loaded with silicon wafers in preparation for phosphorus diffusion

Figure 10.1.4 Wafers being transported through a single-side etch tool to remove the phosphorus-doped silicon on the rear surface.

Figure 10.1.5 Graphite wafer carrier inside a direct plasma PECVD tube reactor.

Figure 10.1.6 Screen printer in operation.

Chapter 10.2

Figure 10.2.1 Structures of common PV encapsulant resins

Figure 10.2.2 Schematic of curing chemistry of PDMS-based encapsulants.

Figure 10.2.3 Example formulation of EVA for PV

Figure 10.2.4 Plot of polymer absorptivity as a function of wavelength alongside the internal quantum efficiency of a typical crystalline silicon cell.

Figure 10.2.5 Solar and crystalline silicon quantum efficiency-weighted transmittance of test samples exposed to 42 global-UV suns in a Xenon arc Weather-Ometer. Samples consist of 0.5 mm encapsulant laminated between two 2.5-cm-square, 3.18-mm-thick, low-Fe, non-Ce glass samples (i.e., highly UV transmissive glass). The top axis corresponds to the amount of UV radition that would be seen with a system tracking the sun and utilizing only the direct spectrum

Figure 10.2.6 Width of edge seal made from different materials that would be necessary to keep moisture below 5% of equilibrium values at a given temperature.

Figure 10.2.7 Penetration depth of moisture between glass plates laminated with different materials as measured by the oxidation of a 100 nm film of Ca.

Chapter 10.3

Figure 10.3.1 Summary of degradation rates reported in the literature for PV modules deployed in different climate zones. The degradation is described according to the changes (under standard test conditions) in short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), and power (Pmax).

Figure 10.3.2 Statistics of PV system problems that were flagged in a study of ~50,000 systems.

Figure 10.3.3 Silicon PV module after ~2 years in the field, showing about 9% degradation in power at standard test conditions.

Figure 10.3.4 Silicon PV module after ~20 years in the field.

Figure 10.3.5 Silicon PV module after 22 years in Florida.

Chapter 10.4

Figure 10.4.1 Top: Symmetrical double-glass module structure with cells being sandwiched between two 2.5 mm thick heat-strengthened glass panels. Bottom: The mechanical stress to the cells is negligible during bending because the cells are located at the Neutral Fiber, i.e. the middle of the symmetrical structure

Figure 10.4.2 Examples of light trapping in advanced PV modules with light capturing ribbons (LCR) and light reflective film (LRF)

Figure 10.4.3 Relative power output increase and relative cost per Watt peak as a function of the gap between cells for a module made of 60 cells (156 mm × 156 mm) with LRF between cells

Chapter 11.1

Figure 11.1.1 Electrical circuit diagram for large PV system.

Figure 11.1.2 Typical residential rooftop system configuration.

Figure 11.1.3 (a) Typical commercial rooftop and (b) carport PV arrays.

Figure 11.1.4 Illustration of exacerbated wind profiles impacting flat roof PV systems.

Figure 11.1.5 PV systems with (a) a single-axis horizontal tracker, and (b) a single-axis tilted tracker.

Figure 11.1.6 250 MWac ground-mounted system in California.

Figure 11.1.7 Impact of varying PV system DC/AC ratio.

Chapter 11.2

Figure 11.2.1 Schematic of conventional single-string PV system (top), DC-DC converter-equipped Smart Modules (middle), and AC micro-inverter-equipped PV system (bottom).

Figure 11.2.2 Block diagrams of PV inverter examples: (top) high-frequency isolated multistage; and (bottom) DC-DC transformerless designs

Figure 11.2.3 High-frequency isolated multi-stage inverter.

Figure 11.2.4 PWM signal (top) generated by comparison of carrier signal with voltage reference (bottom)

Figure 11.2.5 Comparison of MPP voltage and current with change in irradiance (left). Partial shading (right) can result in multiple local maxima, potentially affecting the MPPT operation

Figure 11.2.6 Total efficiency vs DC input voltage and AC output power for an Enphase M215 microinverter.

Figure 11.2.7 Relative weight of measured efficiency at given output power levels for CEC and European conversion efficiency

Chapter 11.3

Figure 11.3.1 Examples of different solar lanterns,

Figure 11.3.2 A typical solar home system in Bangladesh

Figure 11.3.3 Hybrid PV power supply system for autonomous wind measurement station with a system voltage of 12 V, consisting of a PV generator (110 Wp), a direct methanol fuel cell (65 W), a battery storage (660 Ah, C10) and an energy management system. For monitoring purposes, a data logger and several measurement components are integrated into the electric control cabinet.

Figure 11.3.4 Hikers inn, Rappenecker Hütte near Freiburg has been operating since 1987 with a hybrid PV system, now equipped with a PV generator (3.8 kWp), a hydrogen fuel cell (4 kW), a diesel genset (12 kW), a wind generator (1.8 kW) and battery storage (45 kWh).

Figure 11.3.5 Three case studies showing the annual diesel saving potential depending on the PV generator size in relation to peak load of the power system.

Figure 11.3.6 A DC coupled hybrid PV system with different power generators, DC appliances and an inverter supplying AC loads

Figure 11.3.7 An AC coupled hybrid system with different generators and a battery storage supplying typical AC devices

Figure 11.3.8 A DC/AC mixed configuration for hybrid PV systems

Figure 11.3.9 Levelized cost of electricity depending on the solar share for a PV Diesel battery hybrid system. For this study at a location in Uganda the following parameters were used: Peak load 200 kW, Annual consumption: 574 MWh, cost for PV system (incl. power electronics) 1.5 Euro/Wp, cost for battery system 220 Euro/kWh, cost for Diesel genset 273 $/kW invest, 1$/l fuel, 0.7 $/h maintenance.

Figure 11.3.10 Typical construction of tubular (left) and flat plates (right) lead acid-battery.

Figure 11.3.11 Life cycles vs DOD of different types of lead-acid batteries.

Chapter 11.4

Figure 11.4.1 Overview of PV system with components. Four parts can be discerned: (1) modules; (2) connections between module and inverter; (3) inverter; (4) connection between inverter and public electricity grid. Definitions of string and array are indicated, as well as several measured parameters.

Figure 11.4.2 Standard graphs used in PV performance analysis: (a) normalized hourly mean array power versus hourly POA irradiance; (b) bar graph of daily array (light) and reference (dark) yields for a month; (c) normalized histogram of hourly mean POA irradiance values; and (d) performance ratio versus module temperature. Data (May 2015) are from a system at Utrecht University campus

Figure 11.4.3 System yield versus reference yield for a 4.14 kWp PV system.

Figure 11.4.4 PV system power and irradiance for a clear day without shade (a), and with shade (b). Panel (c) shows system yield versus reference yield.

Figure 11.4.5 Distribution of PR values for a sample of 590 Dutch PV systems in 2014

Chapter 11.5

Figure 11.5.1 PV performance modeling process for a grid-connected PV system from sunlight to AC power

Figure 11.5.2 Measured reflection losses on two modules with different top cover glass

Figure 11.5.3 Single diode equivalent circuit

Figure 11.5.4 Five points determined by the Sandia module IV curve model

Figure 11.5.5 Example inverter efficiency profile

Chapter 11.6

Figure 11.6.1 Free-standing and roof mounted Building Added PV in Rotterdam, the Netherlands, 2013 (left) vs Building Integrated PV in Heerlen, the Netherlands, 2013 (right)

Figure 11.6.2 Two examples of BIPV on office buildings, contributing to the environmental consciousness impression of the occupants (left: office building in Barcelona, Spain, 2014, right: office building in Westerlo, Belgium, 2011)

Figure 11.6.3 Two examples of BIPV systems in France (2013) in which the modules are, from a technical point of view, integrated into the building skin, but where the aesthetic integration is lacking

Chapter 11.7

Figure 11.7.1 Photovoltaic products of various product-categories. (a) solar calculator (Sale Stores, 2015), (b) solar watch (Express Watches, 2015), (c) phone charger by Vivien Muller (Muller, 2015), (d) solar-powered bag (Ralph Lauren, 2015), (e) Spark lamp (Spark, 2015), (f) IKEA Sunnan lamp (IKEA, 2015), (g) PC computer mouse Sole-Mio (DDI, 2015), (h) solar lantern (Solar Lantern, 2015), (i) solar garden light (Solar Garden Light, 2015), (j) solar-powered parking meter in Virginia (Matray, 2015), (k) automated trash bin Big Belly (Big Belly, 2015), (l) solar traffic light, (m) Solar-powered car from University of Twente in 2011 (n) Planet Solar Catamaran (PlanetSolar, 2015), (o) Helios solar aircraft (NASA, 2015), (p) solar-powered tent (Harris, 2015), (q) PV-powered chandelier (Renewable Energy Magazine, 2015).

Figure 11.7.2 PV cell efficiencies of c-Si, mc-Si and a-Si at different irradiance conditions respectively at STC, 100W/m², 10W/m² and 1W/m² as stated in the literature until 2014.

Figure 11.7.3 Global horizontal irradiance measurements indoors under mixed indoor lighting and outside the window in The Netherlands, in January 2014, at a distance of 50 cm inside and outside the window respectively

Figure 11.7.4 Comparison of the amount of carbon dioxide emissions required during the life-cycle of four mobile phones, between two different technologies; original battery and solar cover and small battery.

Figure 11.7.5 The tested PV products: (a) Waka Waka light; (b) Waka Waka Power light and charger; (c) Sunnan IKEA lamp; (d) Little Sun light; (e) Beurer kitchen weight scale; and (f) Logitech solar keyboard.

Chapter 12.1

Figure 12.1.1 Overview of the Thomsonstraat in Groningen, which is taking part in the PowerMatching City project

Figure 12.1.2 Remote PV system for PowerMatching City

Figure 12.1.3 Hybrid heat pump system

Figure 12.1.4 Heat pumps

Figure 12.1.5 The Energy Monitor of PowerMatching City. The various energy systems are visually represented as well as their energy production in quantitative data. The PV system is shown on the roof

Figure 12.1.6 The interaction between the generated electricity from the PV system (top) on the electric heat pump (middle) and its buffer (bottom). The buffer fill level represents the state of charge of the heat buffer.

Chapter 12.2

Figure 12.2.1 Number of R&D and demonstration PV smart grid projects starting each year

Figure 12.2.2 Investments in R&D and Demonstration PV smart grid projects in Europe (M€), 2002–2013.

Chapter 13.1

Figure 13.1.1 PV LCOE drivers

Figure 13.1.2 PV module prices vs. cumulative production.

Figure 13.1.3 Solar tracking system with robotic cleaning

Figure 13.1.4 US power generating capacity by initial year of operation, as of 2011.

Chapter 13.2

Figure 13.2.1 The diversity of people’s involvement with PV in housing

Chapter 13.3

Figure 13.3.1 Flow of the life cycle stages, energy, materials, and wastes for PV systems

Figure 13.3.2 Historical evolution of Energy Payback Times. Energy payback times of various PV systems were reduced from about 40 years to 0.5 years from 1970 to 2010. The low numbers correspond to insolation of 2,400 kilowatt-hours per square meter per year (US-SW) and the high numbers correspond to insolation of 1,700 kilowatt-hours per square meter per year (Southern Europe)

Figure 13.3.3 EPBT of PV systems: Rooftop-installed module with insolation =1,700 kWh/(m²·yr) and performance ratio = 0.75; European production

Figure 13.3.4 GHG emissions of PV systems:rooftop-installed module with insolation = 1,700 kWh/(m²·yr) and performance ratio = 0.75; European production