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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Praised for its visual appeal, conversational style and clear explanation of complex ideas with minimal mathematics, Electricity from Sunlight has been thoroughly revised and updated to reflect advances in the global PV market, economics and installed capacity.
Key features of the 2nd edition include:
Electricity from Sunlight: Photovoltaics Systems Integration and Sustainability, Second Edition is an essential primer for new entrants to the PV industry, needing a basic appreciation of complete PV systems, and to students on undergraduate and graduate courses on renewable energy and photovoltaics. It also offers a unique treatise of the sustainability of emerging transformative technologies, which makes it useful to both system analysts and energy policy strategists.
Co-author, Vasilis Fthenakis, is Recipient of the 2018 William R. Cherry Award
The Cherry Award recognizes an individual engineer or scientist who has made a significant contribution to the advancement of the science and technology of photovoltaic energy conversion, with dissemination by substantial publications and presentations. Fthenakis was honored for his pioneering research at the interface of energy and the environment that catalyzed photovoltaic technology advancement and deployment world-wide.
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Veröffentlichungsjahr: 2018
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Table of Contents
Cover
Title Page
About the Authors
Foreword
Preface to the First Edition
Preface to the Second Edition
Acknowledgment to the First Edition
Acknowledgment to the Second Edition
About the Companion Website
1 Introduction
1.1 Energy and Sustainable Development
1.2 The Sun, Earth, and Renewable Energy
1.3 The Solar Resource
1.4 The Magic of Photovoltaics
1.5 A Piece of History
1.6 Coming Up to Date
Appendix 1.A Energy Units and Conversions
Self‐Assessment Questions
Problems
Answers to Questions
References
2 Solar Cells
2.1 Setting the Scene
2.2 Crystalline Silicon
2.3 Second‐Generation Photovoltaics
2.4 Cell Efficiency and Module Cost
2.5 Third‐Generation Solar Cells
Self‐Assessment Questions
Problems
Answers to Questions
References
3 PV Modules and Arrays
3.1 Introduction
3.2 Electrical Performance
3.3 Capturing Sunlight
3.4 One‐Axis Tracking
3.5 Concentration and Two‐Axis Tracking
Appendix 3.A
Self‐Assessment Questions
Problems
Answers to Questions
References
4 Grid‐Connected PV Systems
4.1 Introduction
4.2 From DC to AC
4.3 Completing the System
4.4 Building‐Integrated Photovoltaics (BIPV)
4.5 The Growth of Global PV Markets
4.6 Current Status of the PV Industry
4.7 Large PV Power Plants
4.8 PV Grid Connection and Integration
4.9 Electricity Markets and Types of Power Generators
4.10 The Variability Challenge and Solutions
4.11 Energy Storage
Self‐Assessment Questions
Problems
Answers to Questions
References
5 Stand‐Alone PV Systems
5.1 Remote and Independent
5.2 System Components
5.3 Hybrid Systems
5.4 System Sizing
5.5 Applications
Self‐Assessment Questions
Problems
Answers to Questions
References
6 Photovoltaic Manufacturing
6.1 Production of Crystalline Si Solar Cells
6.2 Opportunities and Challenges in Si PV Manufacturing
6.3 Thin‐Film PV Manufacturing
Self‐Assessment Questions
Problems
Answers to Questions
References
7 PV Growth and Sustainability
7.1 Affordability
7.2 Resource Availability
7.3 Life‐Cycle Environmental Impacts
7.4 The Growth of PV is Sustainable and Greatly Needed
Self‐Assessment Questions
Problems
Answers to Questions
References
Index
End User License Agreement
List of Tables
Chapter 04
Table 4.1 Categories of electricity storage technologies.
Table 4.2 Energy storage technology cost estimates (Akhil
et al
.
20
).
List of Illustrations
Chapter 01
Figure 1.1 Toward the new solar age, this rooftop PV installation at the Mont‐Cenis Academy in Herne, Germany, is on the site of a former coal mine.
Figure 1.2 Three important renewable technologies: PV, wind, and wave.
Figure 1.3 The promise of photovoltaics.
Figure 1.4 A rooftop residential system at Long Island, New York (Vasilis Fthenakis).
Figure 1.5 A large PV utility system in South California.
Figure 1.6 Energy for ever: an installation in Austria.
Figure 1.7 Annual mean insolation just outside the Earth’s atmosphere (top) and at the Earth’s surface (bottom).
Figure 1.8 Spectral distributions of solar energy.
Figure 1.9 Air mass (AM) definitions
Figure 1.10 From sun to PV through the Earth’s atmosphere.
Figure 1.11 A certain magic: “sunflowers” in Korea.
Figure 1.12 Isaac Newton, Edmond Becquerel, and Albert Einstein (Wikipedia).
Figure 1.13 Telstar 1, the first commercial telecommunication satellite; diameter approximately 0.8 m; weight 77 kg.
Figure 1.14 The “learning curve” (price‐experience curve) for PV modules.
Figure 1.15 This PV module powers a solar home system in Bolivia.
Figure 1.16 A 9 kW
p
grid‐connected PV system in Northern Italy.
Figure 1.17 115 kW
p
rooftop installation of the Ford Motor Company in London.
Figure 1.18 PV power plant in Colorado, USA.
Chapter 02
Figure 2.1 Each of these PV modules contains 72 monocrystalline silicon solar cells.
Figure 2.2 The façade of this cable‐car station in the Swiss Alps is covered with multicrystalline silicon PV modules.
Figure 2.3 Chunks of silicon.
Figure 2.4 (a) Silicon crystal lattice; (b) electrons and holes.
Figure 2.5 (a) A phosphorus atom in n‐type silicon provides an extra free electron; (b) a boron atom in p‐type silicon provides an extra hole.
Figure 2.6 (a) A p–n junction; (b) applying forward bias.
Figure 2.7 The voltage–current characteristic of a silicon diode.
Figure 2.8 The basic scheme of a crystalline silicon solar cell.
Figure 2.9 (a) The equivalent circuit of a solar cell; (b) its
I–V
characteristic in the dark.
Figure 2.10 (a) The light‐generated current shifts the cell’s characteristic into the fourth quadrant; (b) a family of
I–V
curves for a 2 W
p
solar cell.
Figure 2.11 Current and power at standard insolation.
Figure 2.12 Effects of temperature on the
I–V
characteristic.
Figure 2.13 Quantum effects in solar cells.
Figure 2.14 The theoretical efficiencies of various solar cell types as a function of energy bandgap.
Figure 2.15 Solar spectrum wavelength and its relationship with semiconductor energy bandgap.
Figure 2.16 Solar cell losses.
Figure 2.17 Optical losses.
Figure 2.18 Contact fingers and bus bars.
Figure 2.19 An antireflection coating reduces reflection from the top surface by cancelation.
Figure 2.20 Texturization by raised pyramids.
Figure 2.21 Light trapping helps keep incoming light within the cell by total internal reflection.
Figure 2.22 Typical recombination sites. The central one represents bulk recombination, the others occur close to surfaces, edges, and contacts.
Figure 2.23 Equivalent circuits and
I–V
characteristics of a solar cell: (a) ideal solar cell; (b) “less than ideal” actual solar cell with series (
R
s
) and shunt (
r
sh
) resistances.
Figure 2.24 (a) Multicrystalline silicon wafer; (b) module.
Figure 2.25 Amorphous silicon PV modules on a building façade.
Figure 2.26 Irregular structure and bonding in a‐Si(H).
Figure 2.27 The basic structure of a single‐junction a‐Si(H) solar cell.
Figure 2.28 A triple‐junction amorphous silicon solar cell.
Figure 2.29 Roll‐to‐roll manufacture of a‐Si solar cells.
Figure 2.30 The basic scheme of a CIGS solar cell.
Figure 2.31 An array of CIS solar modules in Austria.
Figure 2.32 A CdTe solar cell (simplified cross section).
Figure 2.33 Farming the Sun; part of an 810 kW
p
CdTe power plant in rural Germany.
Figure 2.34 Large‐scale farming of the Sun; part of the Desert Sunlight 550 MW
ac
CdTe power plant in California (First Solar).
Figure 2.35 Best research‐cell efficiencies.
Figure 2.36 Efficiencies of record cells and commercial PV modules.
Figure 2.37 Classification of PV technologies superimposed with the current status (solid) and projected evolution (arrows) of c‐Si and CdTe PV technologies.
Figure 2.38 Photon absorption in a triple‐junction cell.
Figure 2.39 A dye‐sensitized solar cell.
14
Figure 2.40 Innovative and flexible: dye‐sensitized solar cells in Australia.
Figure 2.41 (a) Photovoltaic effect in a bulk heterojunction organic solar cell
14
(b) conditions for charge transfer in a donor/acceptor photovoltaic device
14
.
Figure 2.42 Organic photovoltaic with two sub‐cells having different complementary absorption spectra
14
.
Chapter 03
Figure 3.1 A large array of PV modules on a rooftop in Switzerland.
Figure 3.2 Typical construction of a conventional crystalline Si PV module.
Figure 3.3 Innovative design: an example from Japan.
Figure 3.4 (a) A string of cells including one “bad” cell; (b) equivalent circuit; (c) addition of bypass diodes.
Figure 3.5 An array of six modules.
Figure 3.6
I–V
characteristics of a typical monocrystalline silicon module rated at 180 W
p
.
Figure 3.7
I–V
characteristics in strong sunlight (1000 W/m
2
) of four 75 W
p
modules.
Figure 3.8 The sun, a big fusion reactor on the sky, is 93 million miles away, but sunlight takes only 8 light minutes to reach the Earth (University of Oregon website).
Figure 3.9 Instruments measuring solar irradiance.
Figure 3.10 The Earth trajectory around the sun and its rotation around its axis. Declination is the angle that direct (beam) irradiation from the sun hits the equator.
Figure 3.11 Solar trajectories over the northern hemisphere, from a stationary observer on Earth.
Figure 3.12 An alternative view of the solar trajectories.
Figure 3.13 The daily maximum altitude angle of the sun as a function of latitude.
Figure 3.14 A south‐facing PV array tilted at an angle equal to the latitude of the location.
Figure 3.15 Aligning a PV array.
Figure 3.16 Average daily solar radiation in kWh/m
2
on a horizontal surface: in (a) London or Amsterdam; (b) in the Sahara Desert.
Figure 3.17 Daily solar radiation in kWh/m
2
on south‐facing inclined PV arrays in (a) London and (b) the Sahara Desert. In each case three values of tilt are illustrated: 0° (blue), the latitude angle (red), and 90° (green).
Figure 3.18 Vertical and in diffuse light: a large PV façade in Manchester, England.
Figure 3.19 A Sun path chart showing shading effects at the solstice and equinox dates. Solar azimuth is the angular displacement from south of the projection of beam radiation on the horizontal plane.
Figure 3.20 Top view of Solar Pathfinder instrument and side shade tracing on a monthly sun path diagram.
Figure 3.21 Arranging module strings to reduce the effects of shading.
Figure 3.22 One‐axis tracking: (a) horizontal axis (First Solar); (b) tilted (polar) axis (SunPower).
Figure 3.23 Concentrating sunlight onto solar cells using lenses: (a) a circular Fresnel lens with point focus; (b) a linear Fresnel lens with line focus.
Figure 3.24 Two‐stage focusing of light to achieve high concentration.
Figure 3.25 Concentrating sunlight with reflective mirrors.
Figure 3.26 Two‐axis tracking.
Figure 3.27 This two‐axis tracker in Las Vegas, United States, supports multiple point‐focus concentrator modules housing multi‐junction GaAs solar cells and is rated at 53 kW
p
.
Figure 3.28 The frame, the optics, and the cells within the frame in the Amonix system.
Figure 3.29 CPV system optimization challenge.
Figure 3.A.1 The geometric and trigonometric parameters used in the following equations.
Figure 3.A.2 The variation of solar declination over the year.
Figure 3.A.3 Daily incident irradiation (kWh/m
2
) on Massena airport, New York, during year 2000; red shows GHI; blue shows global irradiation on a south facing tilted at latitude plane (44.97°).
Figure 3.A.4 Daily incident irradiation on the Atacama Desert, Chile. Blue shows GHI; red show global irradiation on a north facing tilted at latitude plane (27°); green shows global irradiation of a one‐axis tracker with a horizontal axis; and violet shows the same but with the tracker axis tilted 20° toward the north.
Chapter 04
Figure 4.1 Home PV system connected to the grid.
Figure 4.2 Raising the power level: a 17.6 kW
p
grid‐connected roof installation on the Oslo Innovation Centre, Norway.
Figure 4.3 This Korean power plant uses four 250 kW
p
inverters to connect 1 MW
p
of PV arrays to the grid. The modules are mounted on horizontal single‐axis trackers.
Figure 4.4 PV arrays served by: (a) a single central inverter; (b) two individual string inverters.
Figure 4.5 Scaling up: this 1.6 MW
p
inverter weighs over 20 tons.
Figure 4.6 The Moura power plant in Portugal, rated at 45.6 MW
p
.
Figure 4.7 Array mountings at the Kings Canyon power plant in Australia.
Figure 4.8 Key functions of the combiner/protection units in a domestic PV system.
Figure 4.9 Proclaiming a message: the
Solar Showcase
in Birmingham, England.
Figure 4.10 Proclaiming a message: an eco‐home in Denmark.
Figure 4.11 This building in Tübingen, Germany, proudly proclaims its solar identity.
Figure 4.12 Traditional stone and PV in harmony: a building at the Technical University of Catalonia, Spain.
Figure 4.13 Architects in countries with a tradition of social housing can spread their influence widely. This example is in Amersfoort, the Netherlands.
Figure 4.14 A huge solar pergola at the World Forum of Culture in Barcelona, Spain, supports a 4000 m
2
PV array.
Figure 4.15 The Sydney Olympic Games brought PV to the attention of millions with solar‐powered lighting and more than 600 1 kW
p
arrays on athletes’ houses.
Figure 4.16 This eco‐home in Oxford, England, uses PV modules, water‐heating panels, and passive solar design to reduce its external energy requirements almost to zero.
Figure 4.17 PV louvers replace standard glass shading to provide a dual function.
Figure 4.18 A PV‐covered walkway at an exhibition center in Japan.
Figure 4.19 A 1.6 km PV array gives added purpose to a highway sound barrier in Germany.
Figure 4.20 Sunlight and shadow: a striking interior at the Energy Research Centre of the Netherlands.
Figure 4.21 In harmony with nature: 30 kW
p
of glass/glass modules at the National Marine Aquarium, Plymouth, England.
Figure 4.22 Thin‐film semitransparent modules allow dappled light into this building in Germany.
Figure 4.23 Customer satisfaction: a shop in Tours, France.
Figure 4.24 Global growth of PV deployment.
Figure 4.25 Annual growth of PV deployment.
Figure 4.26 Top 14 countries in terms of cumulative capacity as of 2014; shown in order of increasing annual capacity from top to bottom.
Figure 4.27 Trends in deployment increase and price decrease in the United States.
Figure 4.28 Annual PV global production.
Figure 4.29 A 7.2 kW system in Marchal, Spain.
Figure 4.30 The 23 MW
p
La solar farm in Magascona, Spain.
Figure 4.31 The 1.2 MW PV rooftop system at the University of Queensland, Australia.
Figure 4.32 The 1.17 MW PV rooftop system at the Adelaide Airport, Australia.
Figure 4.33 Section of the 1.6 MW “JFK Solar Park” located on the roofs of three airfreight logistics buildings near JFK International Airport in New York.
Figure 4.34 The 1.3 MW PV power plant at Dimbach, Germany.
Figure 4.35 Section of the 10 MW
ac
PV power plant at Tibet Sangri, China.
Figure 4.36 The 300 MW
ac
PV power plant at Yunnan Jianshui, China.
Figure 4.37 Section of the 290 MW
ac
PV power plant, Agua Caliente, AZ, USA.
Figure 4.38 Start of PV plant construction; support and mounting structures.
Figure 4.39 During PV plant construction, mounting the modules on fixed‐tilt system.
Figure 4.40 Section of the 52.5 MW
ac
one‐axis tracking PV plant during construction, Shams Ma’an, Jordan.
Figure 4.41 52.5 MW
ac
one‐axis trackers, almost completed, Shams Ma’an, Jordan.
Figure 4.42 Section of 550 MW
ac
Desert Sunlight, California, PV plant during construction stages.
Figure 4.43 Section of the 550 MW
ac
Desert Sunlight PV power plant.
Figure 4.44 Close‐up on another session of the 550 MW
ac
Desert Sunlight PV plant.
Figure 4.45 Levelized cost of electricity (LCOE) for utility conventional grid and PV power.
Figure 4.46 The US electric grid: three major interconnects, eight NERC subregions, and about 100 balancing authorities
Figure 4.47 Utility‐scale PV operations center in Mesa, Arizona, USA.
Figure 4.48 PV plant grid integration and control system.
Figure 4.49 Impact of cloud passage in utility PVPS operation; the plant comprises of eight power blocs.
Figure 4.50 Power curtailment at different levels: this figure shows field data from a PV plant operating at around 90 MW power. The brown lines show the power set points and the blue shows the supplied power.
Figure 4.51 Example of a load duration curve.
Figure 4.52 Power generators for load balancing and regulation.
Figure 4.53 Solar resource fluctuations and options to mitigate them.
Figure 4.54 Forecast mean average errors (MAE) are reduced by 39–24% when sky imaging is integrated with satellite data
9
.
Figure 4.55 One‐minute ramp‐rate histograms for a 5 and 80 MW plants near each other in Ontario, Canada. The larger the plant, the smaller the ramp rates.
Figure 4.56 Impact of cloud passage on an 80 MW plant power output in Ontario, Canada. The green line shows irradiation measured on one point (W/m
2
), and the orange line shows the smoothening effect from the aggregate of the inverters (MW).
Figure 4.57 Daily variability over the course of 2 years in (a) Los Angeles and (b) an area of 190 × 190 km
2
around the city.
Figure 4.58 Synergy of PV and wind in New York State.
Figure 4.59 Effect of grid flexibility on PV energy delivery.
Figure 4.60 Comparison of storage systems in terms of discharge times and rated power.
15
Figure 4.61 Pb‐acid battery operational principles; shown anode, cathode, electrolyte, and associated reactions
16
.
Figure 4.62 Battery types: energy density comparisons.
15
Figure 4.63 The basic working mechanism of a Li‐ion battery.
Figure 4.64 Schematic of a flow‐assisted battery.
Figure 4.65 Schematic of the Raccoon Mountain Pumped Hydro Plant (Wikipedia).
Figure 4.66 Schematic of a CAES plant source.
Chapter 05
Figure 5.1 Remote and independent: a stand‐alone system for a farmhouse.
Figure 5.2 Off the grid: PV water pumping for a Moroccan village.
Figure 5.3 Typical charging characteristic of a 12 V lead‐acid battery.
Figure 5.4 Typical discharge characteristics of a 12 V lead‐acid battery.
Figure 5.5 A simple scheme for a low‐power solar home system (SHS).
Figure 5.6 Series charge control.
Figure 5.7 Battery charging with pulse width modulation (PWM).
Figure 5.8 Shunt charge control.
Figure 5.9 This MPPT controller can control a 12 or 24 V system with PV array power up to 500 W
p
and MPP voltages up to 100 V. With dimensions 19 × 15 × 7 cm, it weighs 900 g.
Figure 5.10 Extracting the most from a PV array: the MPPT charge controller.
Figure 5.11 Typical connections for a mid‐range stand‐alone system.
Figure 5.12 This family of inverters covers the power range 200 W to 2 kW (continuous), with system voltages of 12, 24, and 48 V.
Figure 5.13 (a) Efficiency curves for two types of inverter; (b) a daily load profile for a solar home.
Figure 5.14 A PV–diesel hybrid system.
Figure 5.15 Appliances and energy requirements for a stand‐alone system.
Figure 5.16 Daily solar radiation in kWh/m
2
on south‐facing inclined PV arrays for a location at latitude 48°N in southern Germany. Three values of array tilt are illustrated: 33° (blue); 48° (red); and 63° (green).
Figure 5.17 A suitable system for the holiday home.
Figure 5.18 PV encircles the Earth.
Figure 5.19 Wide horizons for PV: the Solar System.
Figure 5.20 The International Space Station, photographed in 2009.
Figure 5.21 The Isle of Eigg lies off the west coast of Scotland.
Figure 5.22 The Isle of Eigg’s renewable energy system.
Figure 5.23 (a) PV on Eigg;(b) wind power on Eigg.
Figure 5.24 (a) The battery banks and (b) some of the main inverter–chargers.
Figure 5.25 Clean and accessible: PV‐pumped water.
Figure 5.26 A system for village water supply.
Figure 5.27 PV for a village water supply in Niger.
Figure 5.28 A large PV water pumping station in Morocco.
Figure 5.29 The solar energy‐water‐environmental Nexus (Vasilis Fthenakis).
Figure 5.30 Solar‐powered catamaran
Solar Flair III
.
Figure 5.31 The pontoon boat
Loon
.
Figure 5.32
PlanetSolar
approaches Monte Carlo after its circumnavigation of the world.
Figure 5.33 Two solar‐powered cars, entered by the universities of Michigan and Minnesota, speed over 100 km/h along a Canadian highway during the 2005 North American Solar Challenge (Wikipedia).
Figure 5.34 It has become commonplace for sailors to install PV modules on the decks of ocean‐going yachts to power cabin lighting, services, and navigation equipment. There is now growing interest in making the sails themselves “photovoltaic”.
Figure 5.35 This installation in the Libyan Desert provides
cathodic protection
, an important application of PV that helps minimize corrosion of metal structures including pipelines.
Figure 5.36 A PV array produces electricity for a meteorological station in Greenland. In this high northern latitude, the vertical array captures much of the available sunlight, and solar cell efficiency is enhanced by the very low temperatures.
Figure 5.37 An increasing number of schools worldwide use PV arrays to generate valuable electricity and stir their students’ imagination for the future of renewable energy.
Figure 5.38 Another example of a large PV array in a remote location: this one helps to transmit information by telecommunications link.
Chapter 06
Figure 6.1 Manufacturing metallurgical silicon using an electric arc reduction furnace.
Figure 6.2 Subsequent steps in manufacturing metallurgical silicon using an electric arc reduction furnace.
Figure 6.3 Production steps from MG‐Si to polysilicon by the Siemens method.
Figure 6.4 Schematic of a Siemens reactor.
Figure 6.5 Interior of Siemens reactor with18 rods of polycrystalline Si.
Figure 6.6 Siemens reactors with 48 rods.
Figure 6.7 The operation of a Siemens reactor. The reactor inputs are trichlorosilane (TCS, SiHCl
3
) and hydrogen (H
2
); the outputs are trichlorosilane (TCS), tetrachlorosilane (TET ‐ SiCl
4
), DCS, H
2
, and HCl.
Figure 6.8 The metallurgical refining process.
Figure 6.9 Polysilicon production processes for the PV industry.
Figure 6.10 The Czochralski method for producing pure monocrystalline Si.
Figure 6.11 Top piece of Czochralski ingot.
Figure 6.12 The directional solidification method for producing pure multicrystalline Si.
Figure 6.13 Products in the basic production steps starting from quartz, metallurgical silicon chunks (or in the case of Elkem Solar their ESS® billet), followed by the mono‐ or multicrystalline ingot, wafers (ingot slices), solar cells, and modules.
Figure 6.14 Multi‐wire saw for cutting Si bricks or ingots into wafers.
Figure 6.15 Tube furnace showing a quartz boat loaded with silicon wafers in preparation for phosphorus diffusion.
Figure 6.16 Silicon Genesis’ kerfless wafering approach.
Figure 6.17 Configurations of CIGS and CdTe photovoltaics.
Figure 6.18 Laser scribing of thin‐film layers; CdTe example (Vasilis Fthenakis).
Figure 6.19 Process sequence for manufacturing Si and thin‐film PV modules.
Figure 6.20 Configuration of CIGS PV
Figure 6.21 Process schematic for CIGS PV.
Figure 6.22 Conceptual schematic of lab‐scale sublimation/vapor transport deposition of CdTe (First Solar).
Figure 6.23 Simplified schematic of industrial vapor transport deposition in CdTe PV manufacturing (First Solar).
Figure 6.24 Configuration of CdTe PV.
Chapter 07
Figure 7.1 The three major pillars of PV large growth sustainability (Concept by Vasilis Fthenakis).
Figure 7.2 Toward grid parity in Europe.
Figure 7.3 Positive and negative cash flows for a PV system.
Figure 7.4 Investing in the future: PV for a school in South Africa.
Figure 7.5 Initial investment, annual costs, and levelized cost of electricity (LCOE).
Figure 7.6 Diverse markets for rooftop PV systems: (a) an elegant home in the developed world and (b) a “mobile” home in Mongolia.
Figure 7.7 Rooftop arrays on the Reichstag building in Berlin exemplify the German government’s support for PV.
Figure 7.8 This PV factory is in Malaga, Spain.
Figure 7.9 Pride of ownership: A family in China.
Figure 7.10 PV modules and low‐energy lights replaced kerosene lighting. Sharedsolar user Uganda, 2012.
Figure 7.11 Enthusiasm for PV.
Figure 7.12 Sharedsolar mini‐grid installation during construction phase. Mali, 2011.
Figure 7.13 Education, a very important part of the package.
Figure 7.14 Effectively inexhaustible: Silicon for solar cells.
Figure 7.15 Projections of tellurium availability for photovoltaics from copper smelters (dashed lines; peaking in ~2055) and total from copper smelters and recycling of end‐of‐life photovoltaic modules (solid lines; continuing upward trend until 2095). The red and blue curves in each pair correspond to high and low projections, respectively.
Figure 7.16 Projections of CdTe photovoltaics: (a) Annual and (b) cumulative production limits under tellurium production constraints shown in Figure 7.15. The red, pink, and blue curves correspond to the optimistic, most‐likely, and conservative scenarios, respectively.
Figure 7.17 Environmentally friendly use of land in Sinzheim, Germany, 1.4 MW plant.
Figure 7.18 The land occupied by PV plants in the southwest of the United States is smaller than the land occupied by coal mines.
7
The picture shows a PV plant in Arizona and a mountain top coal mine in West Virginia.
Figure 7.19 Land transformation during coal mining. S, surface mining; U, underground mining.
Figure 7.20 No need for extra land: A rooftop PV array at Munich Airport.
Figure 7.21 Water use in energy life cycles.
Figure 7.22 External and internal costs.
Figure 7.23 Historical evolution of energy payback times (EPBT) from 50 years down to half a year; published estimates corresponding to insolation of 1700 and 2300 kWh/m
2
/year.
Figure 7.24 The life‐cycle stages of photovoltaics.
Figure 7.25 Energy payback times of PV systems installed under South European and average US irradiation conditions.
Figure 7.26 Energy payback times of PV systems installed in the South United States.
Figure 7.27 Life‐cycle greenhouse gas emissions in electricity generation (as of 2014); PV continues to get better in terms of increasing efficiencies and reducing emissions.
Figure 7.28 Life‐cycle emissions of (a) SO
2
and (b) NO
x
emissions from silicon and CdTe PV modules. BOS includes module supports, cabling, and power conditioning. The estimates are based on rooftop‐mount installation, insolation of 1700 kWh/m
2
/year, performance ratio of 0.75, lifetime of 30 years, and European production with electricity supply from the UCTE grid.
Figure 7.29 Emissions of cadmium in the life cycles of PV compared with those from fossil and nuclear power generation (as of 2014; all PV technologies continue to improve).
Figure 7.30 Process schematic for recycling of crystalline silicon PV modules.
Figure 7.31 Process schematic for recycling of CdTe PV modules.
Figure 7.32 Recycling strengthens the three major pillars of sustainable large growth of PV (Concept Vasilis Fthenakis).
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Electricity from Sunlight
Photovoltaic‐Systems Integration and Sustainability
Second Edition
Vasilis Fthenakis
Columbia UniversityUSA
Paul A Lynn
formerlyImperial College LondonUK
This second edition first published 2018© 2018 John Wiley & Sons Ltd
Edition HistoryJohn Wiley & Sons Ltd (1e, 2010)
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Library of Congress Cataloging‐in‐Publication Data
Names: Fthenakis, Vasilis M., author. | Lynn, Paul A., author.Title: Electricity from sunlight : photovoltaic‐systems integration and sustainability / by Vasilis Fthenakis, Paul A Lynn.Description: Second edition. | Hoboken, NJ : John Wiley & Sons, 2018. | Includes bibliographical references and index. |Identifiers: LCCN 2017040584 (print) | LCCN 2017047711 (ebook) | ISBN 9781118963777 (pdf) | ISBN 9781118963784 (epub) | ISBN 9781118963807 (cloth)Subjects: LCSH: Photovoltaic power generation. | Solar cells. | Solar energy.Classification: LCC TK1087 (ebook) | LCC TK1087 .F764 2018 (print) | DDC 621.31/244–dc23LC record available at https://lccn.loc.gov/2017040584
Cover Design: WileyCover Images: (Top image) © skeijzer/Gettyimages;(Left to right images) © Gyuszko/Gettyimages; © coddy/Gettyimages; © VioNet/Gettyimages; (Bottom image) © Kativ/Gettyimages
About the Authors
Vasilis M. Fthenakis is the founder and director of the Center for Life Cycle Analysis (CLCA), Department of Earth and Environmental Engineering, Columbia University, New York, USA. He is also a senior scientist emeritus at Brookhaven National Laboratory (BNL) where he conducted research for 36 years and directed the National Photovoltaics (PV) Environmental Research Center and several international networks. Dr. Fthenakis is the coauthor and editor of four books and about 400 scientific publications on topics at the interface of energy life cycles and the environment. Currently, he is leading research on solar desalination, energy systems modeling, life‐cycle analysis, and PV recycling.
Paul A. Lynn obtained his B.Sc. (Eng) and Ph.D. degrees from Imperial College London, UK. After several years in the electrical/electronics industry, he lectured at Imperial College and the University of Bristol, latterly as Reader in Electronic Engineering. In 1993 he became the founding managing editor of the prestigious Wiley journal Progress in Photovoltaics and held this position for 14 years. As a retired academic, Dr. Lynn’s continued interest in renewable energy has led to a trilogy of Wiley books and, in his spare time, three solar‐powered boats. He is the author of nine other books and numerous technical papers and articles.
Foreword
Just over 40 years ago, the idea that solar power could make the leap from powering satellites in space to powering the planet was the vision of only a few people brought together by the shock of the first oil embargo. Today, almost everyone sees solar panels on a daily basis. Electricity from Sunlight: Photovoltaic‐Systems Integration and Sustainability describes the journey from the sun’s use in earliest times to tomorrow’s continuum of recyclable materials employed in producing energy from a manufactured good, rather than by consuming Mother Earth’s resources. The exponential increase in applications powered by solar is shown to be directly tied to the predictable cost reduction experienced through economies of scale and continuous technology performance improvements. The book delivers insights that are both inspirational and quantitatively informative by thoroughly documenting many of the pathways for achieving scale that have been established upon foundations of science and experience proven over decades.
Electricity from Sunlight describes the quantification and consideration given to every dimension of the solar value chain: how feedstocks are prepared, how factories consistently operate, how manufacturing environmental health and safety is planned and audited, how life‐cycle benefits are quantified, and how our planet wins at the same time business wins. We now have an existence proof. It is possible to have sustainable development that is economically sustainable.
Sunlight is freely distributed across our planet. The combination of information technology with low‐cost solar technology has established the foundation for an irreversible growth connecting the dots between the supply of cost‐competitive electricity and the need for power everywhere. The book is a roadmap to understanding the cornerstones upon which an industry has been framed so that ideas for totally optimizing that early vision can be explored and accelerated to meet real‐world needs. Here in one place is the guidebook to a clean energy future.
Charlie Gay, Ph.D.Director, Solar Energy Technology OfficeU.S. Department of EnergyWashington, DC
Preface to the First Edition
Photovoltaics (PV), the ‘carbon‐free’ technology that converts sunlight directly into electricity, has grown dramatically in recent years. Unique among the renewable energies in its interaction with the built environment, PV is becoming part of the daily experience of citizens in developed countries as millions of PV modules are installed on rooftops and building facades. People living in sunshine countries will increasingly live in solar homes or receive their electricity from large PV power plants. Many governments around the world are now keen to promote renewable electricity as an essential part of the 21st century’s energy mix, and PV is set for an exciting future.
This book is designed for students and professionals looking for a concise, authoritative, and up‐to‐date introduction to PV and its practical applications. I hope that it will also appeal to the large, and growing, number of thoughtful people who are fascinated by the idea of using solar cells to generate electricity and wish to understand their scientific principles. The book covers some challenging concepts in physics and electronics, but the tone is deliberately lighter than that of most academic texts, and there is comparatively little mathematics. I have included many colour photographs, gathered from around the World, to illustrate PV’s huge and diverse range of practical applications.
In more detail, Chapter 1 introduces PV’s scientific and historical context, suggests something of the magic of this new technology, and summarises its current status. The treatment of silicon solar cells in Chapter 2 includes material in semiconductor physics and quantum theory, described by a few key equations and supported by plenty of discussion. The new types of thin‐film cell that have entered the global PV market in recent years are also introduced. Chapter 3 covers the characteristics of PV modules and arrays, discusses potential problems of interconnection and shading, and outlines the various types of system that track the sun, with or without concentration. The two major categories of PV system, grid‐connected and stand‐alone, provide the material for Chapters 4 and 5 respectively, and Chapter 6 concludes the story with some of the most important economic and environmental issues surrounding PV’s remarkable progress.
Photovoltaic technology seeks to work with nature rather than to dominate or conquer it, satisfying our growing desire to live in tune with Planet Earth. I trust that this book will inspire as well as inform, making its own small contribution to an energy future increasingly based on ‘electricity from sunlight’.
Paul A. LynnButcombe, Bristol, EnglandSpring 2010
Preface to the Second Edition
The eight years since Electricity from Sunlight first appeared have witnessed a remarkable development in the field of renewable energy—the explosive growth of photovoltaics (PV). Global installed capacity, which reached about 40 gigawatts (GW) in 2010, is approaching 400 GW. It is even possible to imagine 1000 GW by 2020—a thousand times greater than at the start of the new millennium.
PV’s meteoric rise is due to a combination of factors: at the technical level, steady improvements in solar cells, modules, and systems; at the international political level, an ever‐increasing awareness of the threats posed by global warming; and at the production level, a dramatic reduction in costs as PV exhibits the well‐known “learning curve” of manufactured products experiencing exponential growth.
This new edition pays special attention to issues raised by PV’s extraordinary progress, especially the integration of large amounts of solar electricity into existing grid networks and its sustainability in terms of markets, resources, and life‐cycle impacts. Chapters 4, 5, and 7 have been revised and greatly expanded, and a brand new chapter on PV manufacturing has been inserted. The other chapters have all been updated.
We hope the new edition will act as an essential primer for entrants to the PV industry needing an up‐to‐date appreciation of the subject. It also offers a unique treatise on the sustainability of emerging transformative technologies, making it valuable to system analysts and energy policy strategists. Last but not least, we have included end‐of‐chapter questions and problems to support instructors and the ever‐increasing number of college and university students taking courses in renewable energy and PV.
Vasilis FthenakisColumbia University and Brookhaven National Laboratory, USA
Paul A Lynnformerly Imperial College London, UKSpring 2018
Acknowledgment to the First Edition
There is nothing like a good set of pictures to illustrate PV’s extraordinary progress and I have enjoyed enlivening the text with colour photographs obtained from around the world. I hope that my readers will regard them as an important and inspirational aspect of the book. They come from widespread sources and I have received generous cooperation from people in many organisations and companies who have provided copyright permissions and, in several cases, suggested stunning alternatives to illustrate particular topics.
I am especially grateful to the two international organisations that have provided the lion’s share of the photographs reproduced in this book:
1. The European Photovoltaic Industry Association (EPIA)
2. The International Energy Agency Photovoltaic Power Systems Programme (IEA PVPS)
3. Additional acknowledgements
I am also grateful to a further group of companies and organisations that have agreed to their photographs appearing in this book, and for help received in each case from the named individual:
Amonix Inc. (Nate Morefield) 3425 Fujita Street, Torrance, CA 90505, USA
Boeing Images (Mary E. Kane), USA
www.boeingimages.com
Dyesol Ltd (Viv Tulloch) P.O. Box 6212, Queanbeyan, NSW 2620, Australia
Dylan Cross Photographer (Dylan Cross), USA
First Solar Inc. (Brandon Michener) Rue de la Science 41, 1040 Brussels, Belgium
Isle of Eigg Heritage Trust (Maggie Fyffe) Isle of Eigg, Inverness‐shire PH42 4RL, Scotland
Padcon GmbH (Peter Perzl) Prinz‐Ludwig‐Strasse 5, 97264 Helmstadt, Germany
Steca Elektronik GmbH (Michael Voigtsberger) Mammostrasse 1, 87700 Memmingen, Germany
Tamarack Lake Electric Boat Company (Montgomery Gisborne) 207 Bayshore Drive, Brechin, Ontario L0K 1B0, Canada
Wind and Sun Ltd (Steve Wade)Leominster, Herefordshire HR6 0NR, England
The publishers acknowledge use of the above photographs, which are reproduced by permission of the copyright holders, and individually acknowledged where they appear in the text.
The use of three photographs from the NASA website, and several pictures from the Wikipedia website is also gratefully acknowledged.
The author of a comparatively short but wide‐ranging book on PV – or any other technology – inevitably draws on many sources for information and inspiration. In my case several longer and more specialised books, valued companions in recent years, have strongly influenced my understanding of PV and I freely acknowledge the debt I owe their authors, often for clear explanations of difficult concepts that I have attempted to summarise. These books are included in the chapter reference lists, and you may notice that a few of them appear rather frequently. I have tried to give adequate and appropriate citations in the text.
My previous books on electrical and electronic subjects have been more in the nature of standard textbooks, illustrated with line drawings and a few black‐and‐white photographs. When the publishers agreed to my proposal for an introductory book on PV containing full‐colour technical drawings and photographs, I realised that a whole new horizon was in prospect, and have enjoyed the challenge of trying to choose and use colour effectively. The photographs, many of them superb, have already been mentioned. It has also been a great pleasure to work closely with David Thompson, whose ability to transform my sometimes rough sketches into clear and attractive technical drawings has been something of an eye‐opener.
For nearly 15 years my main involvement with PV was as Managing Editor of the Wiley international journal Progress in Photovoltaics: Research & Applications. Among the many editorial board members who gave valuable advice over that period, I should particularly like to mention Professor Martin Green of the University of New South Wales (UNSW), world‐renowned for his research and development of silicon solar cells; and Professor Eduardo Lorenzo of the Polytechnic University of Madrid (UPM), whose encyclopaedic knowledge of PV systems and rural electrification was offered unstintingly. It was both a privilege and a pleasure to work with them for many years. And although any shortcomings in this book are certainly my own, any merits are at least partly due to them and other members of the board.
Finally I should like to thank the editorial team at Wiley UK for their enthusiasm and guidance during this project. They, and others, have eased into publication this account of an exciting new technology that magically, and quite literally, produces electricity from sunlight.
Paul A. Lynn
Acknowledgment to the Second Edition
Following Paul Lynn’s lead in including color photographs in the first edition, illustrating PV’s beauty and extraordinary promise, I have added plenty more in this new edition. For the new figures and valuable exchanges, I am grateful to the following individuals and organizations: Mahesh Morjaria, First Solar; Pierre Verlinden, Trina; William Shafarman, University of Delaware; Raed Bkayrat, First Solar; Jason Baxter, Drexel University; Jeff Britt, Global Solar; Steven Hegedus, University of Delaware; Christian Den Heijer, Hukseflux; Vahan Garboushian, Arzon Solar; Ronny Gløckner, Elkem Solar; Markus Gloeckler, First Solar; John Lushetsky, US‐DOE; Vijay Modi, Columbia University; Craig Murphy, MEMC Electronic Materials; John Phufas, JFK Solar Enterprises; Thomas Shilling, Photon; Parikhit Sinha, First Solar; and Arnulf Jäger‐Waldau, European Commission Joint Research Centre.
The organization and content of this second edition owe much to my teaching at Columbia University, and I am grateful to many undergraduate and graduate students whose interest in solar energy and the environment created this publishing opportunity. Especially helpful were three of my former doctorate students who are now pursuing auspicious careers in renewable energy: Marc Perez, currently with Clean Power Research; Rob van Haaren, currently with First Solar; and Thomas Nikolakakis, currently with the International Renewable Energy Agency. I also wish to acknowledge my former postdoctoral associates Annick Anctil, currently with Michigan State University; Jun‐Ki Choi, currently with University of Dayton; Chul Hyung Kim, currently with Ford; Damon Turney, currently with City College of New York; and Wenming Wang, currently with First Solar. Their significant contributions are widely cited. Thanks are also due to my current graduate students Samet Ozturk and Zhuoran Zhang for their help with problem solving and elegant schematics.
I have also benefitted immensely by interacting during my tenure at Brookhaven National Laboratory with individuals leading the energy transition to solar in the United States, including Mike Ahearn, Charlie Gay, Larry Kazmerski, and Ken Zweibel with whom I shared the vision of the Solar Grand Plan.
This second edition is dedicated to my wife Christina Georgakopoulos Fthenakis, an accomplished skin research scientist, for her love and encouragement. We both hope that Electricity from Sunlight: Photovoltaic‐Systems Integration and Sustainability succeeds in clearly defining a pragmatic solution to the risks that climate change and conflicts for energy and water resources present to our children and the generations that follow.
It has been a pleasure to work with Paul Lynn on this new edition, a transatlantic link appreciated by us both.
Vasilis M. Fthenakis
About the Companion Website
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1Introduction
1.1 Energy and Sustainable Development
This book is written by a chemical engineer and an electronic engineer who believe that continuing to burn fossil fuels for energy is not sustainable and that a transition to renewable energy is feasible. Let us start the discussion by reflecting on what sustainability of certain development is all about. “Sustainable development” is characterized as the “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” Now it becomes clear why continuation of using fossil fuels for energy is not sustainable. First, the combustion of fossil fuels results in the release of carbon dioxide (CO2) and other pollutants (NOx, SOx, particulates, mercury, and other toxic metals) into the atmosphere. The increased atmospheric concentrations of these pollutants cause a series of environmental impacts, including global warming and respiratory health effects. Second, the rate at which we consume fossil fuels is much higher than the rate at which they are replenished so mankind cannot rely on this source of energy forever.
The main candidates for facing this dual challenge of carbon dioxide (CO2) emissions and fossil fuel depletion are coal with carbon capture and sequestration (CCS), nuclear, and renewable sources of energy. However, safe and economic concepts for carbon sequestration have not been proven; nuclear suffers from high cost, radioactive waste management, fuel availability, and nuclear weapon proliferation issues; and renewables have been limited by resource limits, high cost, and intermittency problems. Biomass could be a substitute for fossil fuels, but enough land or water to both meet the demand for power and to feed the world’s growing population is not available. Solar energy has huge potential—tens or hundreds of terawatts (TW) are practical, but it suffers from intermittency. Wind resources are less abundant and even more variable than solar, but in many regions they can complement the variability of solar resources.
The cost challenge for solar electricity is being resolved as recent drastic cost reductions in the production of photovoltaics (PV) paved the way for enabling solar technologies to become cost competitive with fossil fuel energy generation. Such cost competitiveness, called “cost grid parity,” has already been accomplished for parts of the southwest United States, Chile, Spain, Italy, and other countries. PV rooftop systems and utility power plants are relatively easy to build and deployment grows fast. Nevertheless solar is still a minor contributor in electricity mixtures worldwide as inertia in energy policy is stalling the transformation urgently needed. To this end, our book aims in conveying the great potential of PV and helping accelerate their deployment in a world longing for sustainable development.
1.2 The Sun, Earth, and Renewable Energy
We are entering a new solar age. For the last few hundred years, humans have been using up fossil fuels that took around 400 million years to form and store underground. We must now put huge effort—technological and political—into energy systems that use the sun’s energy more directly. It is one of the most inspiring challenges facing today’s engineers and scientists and a worthwhile career path for the next generation. PV, the subject of this book, is one of the exciting new technologies that is already helping us toward a solar future.
Most politicians and policymakers agree that a massive redirection of energy policy is essential if planet Earth is to survive the 21st century in reasonable shape. The 21st Conference of the Parties (COP21) that brought 190 countries together in Paris in December 2015 agreed that consistent efforts are needed worldwide to keep the global temperature increase to below 2°C, or preferably below 1.5°C.
This is not simply a matter of fuel reserves. It has become clear that, even if those reserves were unlimited, we could not continue to burn them with impunity. The resulting carbon dioxide emissions and increased global warming would lead to a major environmental crisis if we do not curtail the CO2 concentration in the atmosphere and do it soon, before we are locked into irreversible processes. So the danger is now seen as a double‐edged sword: on the one side, fossil fuel depletion and, on the other, the increasing inability of the natural world to absorb emissions caused by burning what fuel remains.
Back in the 1970s there was very little public discussion about energy sources. In the industrialized world we had become used to the idea that electricity is generated in large centralized power stations, often out of sight as well as mind, and distributed to factories, offices, and homes by a grid system with far‐reaching tentacles. Few people had any idea how the electricity they took for granted was produced, or that the burning of coal, oil, and gas was building up global environmental problems. Those who were aware tended to assume that the advent of nuclear power would prove a panacea; a few even claimed that nuclear electricity would be so cheap that it would not be worth metering! And university engineering courses paid scant attention to energy systems, giving their students what now seems a rather shortsighted set of priorities.
Figure 1.1 Toward the new solar age, this rooftop PV installation at the Mont‐Cenis Academy in Herne, Germany, is on the site of a former coal mine.
(Source: Reproduced with permission of IEA‐PVPS)
Yet even in those years, there were a few brave voices suggesting that all was not well. In his famous book Small is Beautiful,1 first published in 1973, E.F. Schumacher poured scorn on the idea that the problems of production in the industrialized world had been solved. Modern society, he claimed, does not experience itself as part of nature, but as an outside force seeking to dominate and conquer it. And it is the illusion of unlimited powers deriving from the undoubted successes of much of modern technology that is the root cause of our present difficulties. In particular, we are failing to distinguish between the capital and income components of the Earth’s resources. We use up capital, including oil and gas reserves, as if they were steady and sustainable income. But they are actually once‐and‐only capital. It is like selling the family silver and going on a binge.
Schumacher’s message, once ignored or derided by the majority, is increasingly seen as the essence of sustainable development. For the good of planet Earth and future generations, we have started to distinguish between capital and income and to invest heavily in renewable technologies—including solar, wind, and wave power—that produce electrical energy free of carbon emissions. The message has been powerfully reinforced by former US Vice President Al Gore, whose inspirational lecture tours and video presentation An Inconvenient Truth2 have been watched by many millions of people around the world. Most importantly, the vision was captured by industry leaders who made solar and wind systems affordable and continue to advance them.
Whereas the fossil fuels laid down by solar energy over hundreds of millions of years must surely be regarded as capital, the sun’s radiation beamed at us day by day, year by year, and century by century is effectively free income to be used or ignored as we wish. This income is expected to flow for billions of years. Nothing is “wasted” or exhausted if we don’t use it because it is there anyway. The challenge is to harness such renewable energy effectively, designing and creating efficient and hopefully inspiring machines to serve humankind without disabling the planet.
Figure 1.2 Three important renewable technologies: PV, wind, and wave.
We should perhaps consider the meaning of renewable energy a little more carefully. It implies energy that is sustainable in the sense of being available in the long term without significantly depleting the Earth’s capital resources, or causing environmental damage that cannot readily be repaired by nature itself. In his excellent book A Solar Manifesto,3 the late German politician Hermann Scheer considered planet Earth in its totality as an energy conversion system. He notes how, in its early stages, human society was itself the most efficient energy converter, using food to produce muscle power and later enhancing this with simple mechanical tools. Subsequent stages—releasing relatively large amounts of energy by burning wood and focusing energy where it is needed by building sailing ships for transport and windmills for water pumping—were still essentially renewable activities in the previously mentioned sense.
What really changed things was the 19th‐century development of the steam engine for factory production and steam navigation. Here, almost at a stroke, the heat energy locked in coal was converted into powerful and highly concentrated motion. The industrial society was born. And ever since we have continued burning coal, oil, and gas in ways that pay no attention to the natural rhythms of the Earth and its ability to absorb wastes and by‐products, or to keep providing energy capital. Our approach has become the opposite of renewable and it is high time to change priorities.
Since the reduction of carbon emissions is a principal advantage of PV, wind, and wave technologies, we should recognize that this benefit is also proclaimed by supporters of nuclear power and carbon dioxide capture and carbon sequestration (CCS) technologies. But frankly they make strange bedfellows, in spite of sometimes being lumped together as “carbon‐free.” It is true that all offer electricity generation without substantial carbon emissions, but in almost every other respect they are poles apart. The renewables offer the prospect of widespread, both large‐ and small‐scale electricity generations, but nuclear must, by its very nature, continue the practice of building huge centralized power stations. CCS could, in the best case, capture only a part of CO2 emissions, but there are not safe sequestration options, and it would increase health, safety, and environmental impacts at the coal mining areas and in subsequent stages. Both fossil fuels and uranium are depletable resources. PV, wind, and wave need no fuel and produce no waste in operation; the nuclear industry is beset by problems of radioactive waste disposal. On the whole, renewable technologies pose no serious problems of safety or susceptibility to terrorist attack—advantages that nuclear power can hardly claim. And finally there is the issue of nuclear proliferation and the difficulty of isolating civil nuclear power from nuclear weapons production. Taken together these factors amount to a profound divergence of technological expertise and political attitudes, even of philosophy.
It would however be unfair to pretend that renewable energy is the perfect answer. For a start such renewables as PV, wind, and wave are relatively diffused and intermittent. Often, they are rather unpredictable. And although the “fuel” is free and the waste products are minimal, up‐front investment costs tend to be large. There are certainly major challenges to be faced and overcome as we move toward a solar future, and these are discussed comprehensively in this new edition.
Our story now moves on toward the exciting technology of PV, arguably the most elegant and direct way of generating renewable electricity. But before getting involved in the details of solar cells and systems, it is necessary to appreciate something of the nature of solar radiation—the gift of a steady flow of energy income that sustains life on the planet.
Figure 1.3 The promise of photovoltaics.
(Source: Reproduced with permission of European Photovoltaic Industry Association)
Figure 1.4 A rooftop residential system at Long Island, New York (Vasilis Fthenakis).
Figure 1.5 A large PV utility system in South California.
(Source: Reproduced with permission of Desert Sunlight, First Solar/NEXTera Energy)
1.3 The Solar Resource
The sun sends an almost unimaginable amount of energy toward planet Earth—around one hundred thousand TW; 1 TW is 1 trillion watts. In electrical supply terms this is equivalent to the output of about 100 million modern fossil fuel or nuclear power stations. To state it another way, the sun provides in about an hour the present energy requirements of the entire human population for a whole year. It seems that all we need do to convert society “from carbon to solar” is to tap into a tiny proportion of this vast potential.
