NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Contract No. DE-AC36-08GO28308

Utility-Scale Concentrating 

Solar Power and Photovoltaics 

Projects: A Technology and 

Market Overview

Michael Mendelsohn, Travis Lowder, and 

Brendan Canavan

Technical Report

NREL/TP-6A20-51137

April 2012
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy 

Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

National Renewable Energy Laboratory

1617 Cole Boulevard

Golden, Colorado 80401

303-275-3000 • www.nrel.gov

Contract No. DE-AC36-08GO28308

Utility-Scale Concentrating 

Solar Power and Photovoltaics 

Projects: A Technology and 

Market Overview

Michael Mendelsohn, Travis Lowder, and 

Brendan Canavan

Prepared under Task No. SM10.2442

Technical Report

NREL/TP-6A20-51137

April 2012
NOTICE

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iii

Acknowledgments

This work was funded by the U.S. Department of Energy’s (DOE) Solar Program. The authors 

wish to thank Robert Margolis, Mark Mehos, and Craig Turchi of the National Renewable 

Energy Laboratory (NREL) for their guidance and helpful input. In addition, thanks go out to 

Karlynn Cory, Bethany Speer, Travis Lowder, Hillary Dobos, Jeffrey Logan, and David Kline of 

NREL and Adam Goldstein and Kyle Rudzinski of DOE. We would also like to thank the 

individuals who reviewed various drafts of this report, including John Bartlett, formerly with the 

DOE, Albert Fong of Albiasa Corporation, Andy Taylor of BrightSource Energy, and 

Christopher Walti of Acciona Energy.

Finally, the authors thank Mary Lukkonen from NREL’s Technical Communications Office for 

providing editorial support.
iv

List of Acronyms

AC alternating current

a-Si amorphous silicon

b bar

Bell Bell Solar Thermal

BLM Bureau of Land Management

CEC California Energy Commission

CdTe cadmium telluride

CIGS copper indium gallium selenide

CPV concentrating photovoltaic

c-Si crystalline silicon

CSP concentrating solar power

DC direct current

DOE Department of Energy

FPL Florida Power and Light

ft foot

HTF heat transfer fluid

ISO independent system operator

IOU investor-owned utility

MW megawatt

NERC North American Energy Reliability Corporation

PEIS Programmatic Environmental Impact Statement

PG&E Pacific Gas and Electric

PPA power purchase agreement

PV photovoltaic

RPS renewable portfolio standard

SCE Southern California Edison

SDG&E San Diego Gas and Electric

SEGS Solar Energy Generating System

SGIP small generator interconnection process

TEP Tucson Electric Power

TES thermal energy system
v

Executive Summary

Solar energy technologies continue to be deployed at unprecedented levels, aided significantly

by the advent of large-scale projects that sell their power directly to electric utilities. Such utilityscale systems can deploy solar technologies far faster than traditional “behind-the-meter” 

projects designed to offset retail load. These systems achieve significant economies of scale 

during construction and operation, and in attracting financial capital, which can in turn reduce 

the delivered cost of power.

This is the first in a series of three reports on utility-scale solar installation in the United States. 

This report serves as: (1) a primer on utility-scale solar technologies and (2) a summary of the

current state of the U.S. utility-scale solar market. The second report overviews policies and 

financing of utility-scale solar systems; the third report assesses the impact of financial structures 

on the cost of energy from utility-scale systems.

Utility-scale solar projects are generally categorized in one of two basic groups: concentrating 

solar power (CSP) and photovoltaic (PV). CSP systems generally include four commercially 

available technologies: CSP trough, CSP tower, parabolic dish, and linear Fresnel reflector, 

although only CSP trough and CSP tower projects are currently being deployed. CSP systems 

can also be categorized as hybrid systems, which combine a solar-based system and a fossil fuel 

energy system to produce electricity or steam. 

PV systems usually include either crystalline silicon (c-Si) or thin-film technologies. Thin film 

includes an array of advanced materials, but only one—cadmium telluride (CdTe)—has had 

significant success in utility-scale solar development. Additionally, this report covers

concentrating photovoltaic (CPV) systems,

1 which only recently have gained traction in the 

utility-scale market with several signed contracts.

According to a database maintained by the National Renewable Energy Laboratory (NREL),

2

there are approximately 16,043 megawatts (MW) of utility-scale solar resources under 

development3 in the United States as of January 2012 (see Figure ES-1). PV projects make up 

the overwhelming majority (about 72%) of facilities under development. While many developers 

have specified that their projects will use PV (e.g., c-Si or CdTe), in some cases the technology 

will be selected just prior to construction. This selection will likely depend on module pricing at 

the time of order placement once all necessary permits have been obtained and pre-construction 

activities completed. It is not uncommon, especially given the recent drop in c-Si module prices, 

for developers to switch technologies in the planning phase.

According to NREL’s internal database, CdTe thin-film technology represents about one-fifth of 

the total inventory of planned utility-scale solar projects and nearly one-third of total planned PV 

 1 This report categorizes CPV as a PV technology, though some analysts group it under CSP.

2 This database was corroborated by similar databases maintained by the Solar Energy Industries Association (SEIA 

2011a) and SNL Financial.

3 For this paper, “utility-scale” is defined as projects 5 MW or larger. These projects were either publicly announced 

and hold a long-term power purchase agreement or were announced directly by a utility. Public announcements are 

made via press releases.
vi

projects4

. First Solar was once considered the sole or joint developer of all utility-scale CdTe

projects under development in the United States, though this is changing with the entrance of 

General Electric into the CdTe market. GE is currently contracted to supply panels to the 20 MW 

Illinois Solar plant being developed by Invenergy. 

Approximately 8,224 MW of developing projects are utilizing c-Si modules or have not 

indicated final technology selection. The majority of these projects are expected to select c-Sibased modules. Per NREL’s criteria—5 MW or larger and holding a long-term contract—

approximately 11,500 MW of total PV capacity is under development in the United States, 

including c-Si, CdTe, copper-indium-selenide (CIS) 5 modules, and CPV technologies. 

Among CSP projects, tower systems have a slight market penetration edge over parabolic 

troughs (about 16% versus 9% of all utility-scale solar systems under development). NREL’s 

project announcements database indicates that the tower market is dominated by one developer,

BrightSource Energy, who holds over 2.2 GW of PPAs with California utilities. Solar 

Millennium was the principal developer in the trough space, but the company’s announced 

switch to PV and subsequent sale of all proposed projects6 to solarhybrid has left only six trough 

developers and no clear market front-runners.

Figure ES-1 provides an overview of the U.S. utility-scale solar market. Two cutting-edge solar 

technologies, Enviromission’s solar chimney and Solaren’s space solar project, are indicated as

“Other” because they hold PPAs and constitute significant additions to the total capacity under 

development, but they are not categorized as traditional CSP or PV technologies. Two 

solar/fossil hybrid plants representing a combined 100 MW of solar capacity are included as a 

separate category to note their distinct approach; both plants will use solar power to supplement 

natural gas-fired generation. Finally, CIS is included because of the recent announcement that 

Solar Frontier, the Japanese CIS manufacturer, will supply up to 150 MW of panels to energy 

developer enXco for use in their PPA contracts with San Diego Gas and Electric (SDG&E).

 4 In the energy industry, some, if not many, planned projects will not reach completion. Therefore, we assume this 

figure to be greater than what will be delivered by the current pipeline of projects.

5 Copper-indium-gallium-selenide (CIGS) is perhaps the more common version of this thin-film technology. Solar 

Frontier, the sole supplier of CIS/CIGS thin-film modules to the utility-scale market (as of January 2012), does not 

use gallium in their semi-conductor blend. 6 Solar Millennium also filed for insolvency in December 2011 (Wesoff and Prior 2011). 
vii

Currently, multiple utility-scale systems are producing power on a consistent basis. The nine 

solar trough CSP plants that comprise the solar energy generating system (SEGS) in California’s 

Mojave Desert constitute the majority of CSP. The SEGS units commenced commercial 

operation from 1984–1991 with several additional utility-scale CSP projects coming online

recently (EIA 2008). In 2007, the 64 MW Nevada Solar One project, a CSP trough plant 

developed by Acciona Solar Power, became operational (Acciona 2010). Two 5-MW 

demonstration facilities developed by Ausra and eSolar also became operational in 2008 and 

2009, respectively (Ausra 2008; eSolar 2009). There are over 40 utility-scale PV facilities 

currently operational in the United States, amounting to some 673 MW of capacity. See 

Appendix Table A-1 for a full list of operating utility-scale PV plants.

CSP Trough, 

1,375 

CSP Tower, 

2,655 

Hybrid, 100 

PV: CdTe, 2,668 

PV: C-Si or NA, 

8,224 

PV: CPV, 471 

PV: CIS, 150 

Other, 400 

Total Solar Capacity in 

Development: 

16,043 MW

Figure ES-1. Total U.S. utility-scale solar capacity under development (all numbers in MW)
viii

Table of Contents

List of Figures ............................................................................................................................................ix

List of Tables ..............................................................................................................................................ix

1 Introduction........................................................................................................................................... 1

1.1 Utility-Scale Market Overview........................................................................................ 1

2 Concentrating Solar Power ................................................................................................................. 3

2.1 CSP Trough...................................................................................................................... 5

2.1.1 Technology Overview............................................................................................5

2.1.2 CSP Trough Market Overview...............................................................................6

2.2 CSP Tower....................................................................................................................... 7

2.2.1 Technology Overview............................................................................................7

2.2.2 CSP Tower Market Overview................................................................................9

2.3 Parabolic Dish................................................................................................................ 10

2.3.1 Technology Overview..........................................................................................10

2.3.2 Parabolic Dish Market Overview.........................................................................11

2.4 Linear Fresnel Reflector ................................................................................................ 11

2.4.1 Technology Overview..........................................................................................11

2.4.2 Linear Fresnel Reflector Market Overview .........................................................12

2.5 Solar-Fossil Hybrid Power............................................................................................. 12

2.5.1 Technology Overview..........................................................................................12

2.5.2 Solar/Fossil Hybrid Market Overview .................................................................13

2.6 Thermal Energy Storage ................................................................................................ 14

2.6.1 Technology Overview..........................................................................................15

2.6.2 Thermal Energy Storage Market Overview .........................................................16

2.7 Cooling Systems ............................................................................................................ 17

3 Photovoltaic Solar Power ..................................................................................................................19

3.1 Traditional PV................................................................................................................ 19

3.1.1 Technology Overview..........................................................................................19

3.1.2 PV Market Overview ...........................................................................................23

3.2 Concentrating PV........................................................................................................... 26

3.2.1 Technology Overview..........................................................................................26

3.2.2 CPV Market Overview.........................................................................................27

4 Summary of Market Highlights..........................................................................................................30

References.................................................................................................................................................31

Appendix A: Operating Utility-Scale Solar Plants .................................................................................41

Appendix B: Utility-Scale Solar PV Projects Under Development.......................................................44

Appendix C: Utility-Scale Solar and Power Purchase Agreements.....................................................53

Appendix D: The Solar Resource ............................................................................................................54
ix

List of Figures

Figure ES-1. Total U.S. utility-scale solar capacity under development (all numbers in MW)... vii

Figure 1. Total U.S. utility-scale solar capacity in operation as of January 2012 (all numbers in 

MW)..............................................................................................................................2

Figure 2. Total U.S. utility-scale solar capacity under development (all numbers in MW)............2

Figure 3. SEGS 4, Kramer Junction, California ..............................................................................4

Figure 4. CSP trough schematic.......................................................................................................5

Figure 5. The Nevada Solar One CSP trough system came online in 2007 ....................................6

Figure 6. CSP tower schematic........................................................................................................8

Figure 7. The Solar One facility in California employed CSP Tower technology..........................8

Figure 8. Schematic of a parabolic dish system.............................................................................10

Figure 9. Linear Fresnel reflector schematic .................................................................................12

Figure 10. Rendering of a solar/fossil hybrid facility....................................................................13

Figure 11. Solar thermal storage extends the power production period ........................................14

Figure 12. The Solar Two system in California included a thermal energy storage system .........15

Figure 13. Comparison of capacity factor by technologies ...........................................................17

Figure 14. SunEdison's 8.2 MW Alamosa plant............................................................................19

Figure 15. Utility-scale PV facility by cost component.................................................................23

Figure 16. CPV modules at the SolarTAC testing facility in Aurora, Colorado ...........................28

Figure C-1. Leading utilities with utility-scale solar in development (under contract or planned)53

Figure D-1. Concentrating and PV solar resources in the United States.......................................54

Figure D-2. Solar resource rear southern California without a filter (left) and with multiple filters 

applied (right) .............................................................................................................55

List of Tables

Table 1. Operating Utility-Scale CSP Projects in the United States................................................3

Table 2. U.S. Utility-Scale CSP Trough Plants in Development.....................................................7

Table 3. U.S. Utility-Scale Central Receiver Projects in Development ........................................10

Table 4. U.S. Utility-Scale Solar-Fossil Hybrid Projects Under Development.............................13

Table 5. Water Usage Requirements for Electric Generation Technologies.................................18

Table 6. Derate Factors for Photovoltaic System Components.....................................................21

Table 7. CPV Concentration Classes.............................................................................................27

Table 8. CPV Systems Under Development..................................................................................29

Table A-1. Operating Utility-Scale PV Plants...............................................................................41

Table B-1. Distributed Utility-Scale PV Systems in Development (< 20 MW)............................44

Table B-2. Mid-Sized PV Projects Currently in Development (20–50 MW)................................48

Table B-3. Large-Sized PV Projects Currently in Development (> 50 MW)................................51
1 

1 Introduction

Drivers ranging from energy security and cleaner air to global economic competitiveness and 

rapidly falling costs are sparking a significant shift in energy generation policy and planning. 

Electric utilities in the United States and the regulatory agencies that oversee them are increasing 

renewable energy use to meet electric load. Technological advances in materials and components

and heightened experience among market entities are leading the way to more cost-effective 

renewable power production. Renewables have also significantly benefitted from a raft of 

support policies and incentives at the municipal, state, and federal levels. These include federal 

tax credits, cash grants, loan guarantee programs, feed-in tariffs, and state renewable portfolio 

standards (RPS),

7

 which are discussed in detail in the second utility-scale solar report. For 

example, California’s RPS, the most robust in the United States, with a required 33% of 

renewable generation from its investor-owned utilities (IOUs), has touched off a spate of solar 

procurement in the last two years. Today, California’s three IOUs hold PPAs with nearly 72% of 

the total solar capacity under development in the United States (see Appendix C).

Supportive policies, financial innovations, and plummeting technology costs have spurred utilityscale8 solar market development in the United States. This report introduces that growing

market. It has two objectives: (1) to summarize solar technologies deployed at utility-scale

installations, and (2) to provide a market overview of U.S. deployment activities. The report is 

divided by technology type: Section 2 deals with CSP technologies, and Section 3 deals with PV 

solar power technologies. Market overviews for each technology are provided at the conclusion 

of each subsection. This report only considers projects already contracted to sell power [typically 

in the form of a power purchase agreement (PPA)]. 

1.1 Utility-Scale Market Overview

Approximately 1,176 MW of utility-scale solar power was operational as of January 2012 (see 

Figure 1). About 43% (503 MW) of this capacity is furnished by CSP facilities, all but 10 MW of 

which utilize trough technology; the remaining 57% of this capacity comes from PV 

installations. Crystalline silicon (C-Si) and cadmium telluride (CdTe) comprise the majority of 

technologies deployed at these installations with 58.0% and 34.5% representation, respectively. 

Amorphous silicon (a-Si), another thin-film technology, represents about 7.0% of total PV 

installations, and concentrating photovoltaic (CPV) about 0.5%. 

 

7 RPS policies are essentially mandated quotas for renewable energy generation as a proportion of total electricity 

production.

8 For this paper, “utility-scale” is defined as any solar electric system with a capacity of 5 MW and above. Such 

utility-scale installations can deploy solar technologies far faster than traditional “behind-the-meter” projects 

designed to offset retail load. These systems employ significant economies of scale during construction, operation, 

and financial capital attraction, which can reduce the delivered cost of power. 
2

Figure 1. Total U.S. utility-scale solar capacity in operation as of January 2012 (all numbers in MW)

Figure 2 illustrates that PV capacity will continue to outpace CSP in the United States as more 

developing projects come online. Nearly all utility-scale CSP plants today use troughs; however,

most planned CSP capacity will not use troughs. Instead, CSP towers have become the preferred 

technology, with over 2,655 MW of projects under contract. CSP tower developer BrightSource 

holds the majority of the PPAs, with about 2.2 GW of capacity (82% of the total planned CSP 

capacity). Recent CSP trough market contraction was largely the result of developer Solar

Millennium’s technology swap for their Blythe, Amargosa, and Palen facilities. At least 2 GW of 

CSP troughs were scrapped for PV because of what Solar Millennium described as more 

“favorable conditions in the PV and commercial bank markets” (PV Magazine 2011).

Figure 2. Total U.S. utility-scale solar capacity under development (all numbers in MW)

CSP, 503

CdTe, 232

c-Si, 387

a-Si, 50

CPV, 4

PV, 673

Total Solar Capacity in Operation:

1,176 MW

CSP Trough, 

1,375 

CSP Tower, 

2,655 

Hybrid, 100 

PV: CdTe, 2,668 

PV: C-Si or NA, 

8,224 

PV: CPV, 471 

PV: CIS, 150 

Other, 400 

Total Solar Capacity in 

Development: 

16,043 MW
3

2 Concentrating Solar Power

CSP systems produce electricity by focusing sunlight to heat a fluid. The fluid then boils water to 

create steam that spins a conventional turbine and generates electricity or it powers an engine 

that produces electricity (Richter et al. 2009). CSP plants consist of three major subsystems: one 

that collects solar energy and converts it to thermal energy; a second that converts the thermal 

energy to electricity; and a third that stores thermal energy collected from the solar field and 

subsequently dispatches the energy to the power block. 

There are currently 503 MW of utility-scale CSP facilities operating domestically. 

Table 1. Operating Utility-Scale CSP Projects in the United States

Plant Capacity (MW) Developer Technology Location PPA With

Kimberlina 5 Areva Linear 

Fresnel

Bakersfield, 

California

Pacific Gas &

Electric 

(PG&E)

Martin Next 

Generation 

Solar

75 Florida Power & 

Light CSP Trough Martin County, 

Florida

Florida Power 

and Light 

(FPL)

Nevada Solar 

One 64 Acciona CSP Trough Boulder City, 

Nevada PG&E

Sierra 

SunTower 5 eSolar CSP Tower Lancaster, 

California

Southern 

California 

Edison (SCE)

SEGS 1-9 354 Luz 

International

CSP

Trough

Mojave Desert, 

California SCE

Total 503

The first large-scale, commercial CSP stations were the solar energy generating systems (SEGS)

built by Luz International, Ltd. from 1984–1991 (DOE 2010c). Nine plants were built in three 

separate locations for a total of 354 MW. Figure 3 shows SEGS 4, located in Kramer Junction, 

California, which has a peak output of 150 MW. SEGS 1 and 2 have a combined maximum 

output of 44 MW and are located in Daggett, California. SEGS 8 and 9 have a combined 

maximum output of 160 MW and are located in Harper Lake, California. NextEra operates and 

partially owns SEGS 3–9, with a combined maximum output of 310 MW (NextEra 2010). 

The latest CSP plant to be developed was the 75 MW Martin Next Generation Solar Energy 

Center developed by and for NextEra subsidiary Florida Power and Light (FPL). The plant was 

completed in 2010 (FPL 2010). This facility uses CSP trough technology to supplement the 

3,705 MW gas- and oil-fired Martin Generation facility and is considered in this report to be a

solar/fossil hybrid plant.
4

Figure 3. SEGS 4, Kramer Junction, California

Source: PIX 14955

CSP systems are unique in the renewable energy sector in that they can integrate large-scale 

thermal energy storage (TES). The first utility-scale plants with storage are now operating in 

Spain (Andasol 1–3) and were developed by Solar Millennium (Solar Millennium 2010). At least 

six plants with TES are currently in development in the United States—the 250 MW Solana 

Solar plant by Abengoa Solar (6 hours of dispatchable storage), the 110 MW Crescent Dunes 

plant by Solar Reserve (10 hours of dispatchable storage), the 5 MW Bell Solar Thermal by Bell 

Energy (storage capacity unknown), and three BrightSource projects whose locations and storage 

capacities are yet undisclosed (Wesoff 2010; Wesoff 2011; Environmental Leader 2010; 

BrightSource Energy 2011a). Solana and Crescent Dunes finalized loan guarantees from the U.S. 

Department of Energy (DOE) for $1.45 billion and $737 million, respectively, to support project 

development (DOE 2011c). 

CSP plants can be functionally integrated with fossil fuel plants to create hybrid CSP-fossil 

power plants that can offer peak and base-load power capability. Fossil hybrid plants, also 

known as integrated solar combined cycle, are under construction in the United States (Florida) 

and North Africa, including Egypt, Algeria, and Morocco (Richter et al. 2009).

Solar thermal power requires approximately 3–8 acres/MW, depending on the technology and 

amount of TES. For example, SEGS 3–9 (with a combined capacity of 310 MW) cover more 

than 1,500 acres, averaging 4.84 acres/MW of gross maximum output (NextEra 2010). In 

contrast, the Solana station with 6 hours of dispatchable storage will cover approximately 

3 square miles, or 6.86 acres/MW of gross maximum output (Solana Solar 2009). 

Like other steam-based technologies, CSP (other than parabolic dish) utilizes steam to spin a 

turbine. Water consumption is a primary consideration for these facilities and can vary from 
5

700–900 gal/MWh, although alternative cooling methods, such as air cooling, can drastically 

reduce this value at the expense of some efficiency loss and increased cost (Stoddard 2008). 

CSP systems are generally classified by the process in which each device collects solar energy. 

Sections 2.1–2.4 illustrate and compare four primary technologies—CSP trough, CSP tower, 

parabolic dish, and linear Fresnel reflector. Although only the first two are currently in utilityscale development in the United States, information on CSP-related thermal storage and cooling 

technologies is also provided. 

2.1 CSP Trough

2.1.1 Technology Overview

CSP trough (also referred to as parabolic trough) systems use curved mirrors and single-axis 

tracking to follow the sun throughout the day, concentrating sunlight on thermally efficient 

receiver tubes or heat collection elements. A heat transfer fluid (HTF)—typically synthetic oil, 

molten salt, or steam—circulates in the tubes absorbing the sun’s heat before passing through 

multiple heat exchangers to produce steam. The steam spins a conventional steam cycle turbine

to generate electricity or it is integrated into a combined steam and gas turbine cycle when used 

in hybrid configurations. Utility-scale collector fields are made up of many parallel rows of 

troughs connected by receiver tubes in series. Rows are typically aligned on a north-south 

formation axis to track the sun from east to west. Site requirements for a solar trough system 

include relatively level land, although the solar fields can be divided into two or more terraces.

Figure 4 provides a schematic of a CSP trough plant. 

Solar troughs are considered the most mature and commercially proven of the CSP technologies. 

In utility settings, solar trough power plants have shown consistent performance when connected 

to the electric grid.9 Improved operating flexibility and dispatchability has been achieved 

through integration with hybrid fossil systems as well as through demonstrated TES capabilities. 

 9 Beyond SEGS and Nevada Solar One, applications exist in Israel, Algeria, and Spain.

Figure 4. CSP trough schematic

Source: Department of Energy 2011b
6

There are advantages and disadvantages of different HTFs. Synthetic fuels remain viscous at 

lower temperatures during the night and on cloudy days but lose efficiency in the heat transfer 

process (Herrmann et al. 2002). Molten salt, on the other hand, is a highly efficient heat transfer 

medium that solidifies at lower temperatures. Neither synthetic fuels nor molten salts can directly 

drive a turbine and therefore must use heat exchangers to boil water and spin a steam turbine. 

Using steam directly as an HTF is advantageous because it does not require heat exchange 

equipment; however, it is not very efficient relative to other transfer fluids because it cannot 

reach high enough temperatures. Further discussion of TES is provided in Section 2.6.

2.1.2 CSP Trough Market Overview

At present, roughly 1,375 MW of utility-scale CSP trough plants are in development with

PPAs

10 in place (Table 2). This figure excludes the 100 MW of solar/fossil hybrid plants 

currently in development. Pacific Gas and Electric (PG&E) holds the majority of trough PPAs, 

totaling 530 MW.

 10 PPAs are contracts between power producers and power purchasers for the long-term sale of electricity. See 

Appendix B for more information.

Figure 5. The Nevada Solar One CSP trough system came online in 2007

Source: PIX 16603
7

Table 2. U.S. Utility-Scale CSP Trough Plants in Development

Plant MW Developer Location PPA With

Bell Solar Thermal 5 Bell Energy Tucson, Arizona Tucson Electric 

Power

Bethel Energy 50 Bethel Energy, 

LLC

Imperial Valley, 

California

San Diego Gas & 

Electric

Ft. Irwin Solar Power 

Project 500 Acciona Solar Power Ft. Irwin, California U.S. Army

Genesis Solar Energy 

Project 250 NextEra Riverside County, California PG&E

Mojave Solar Power 

Project 280 Abengoa San Bernardino County, California PG&E

Solana Generating 

Plant 280 Abengoa Gila Bend, Arizona Arizona Public Service

Westside Solar Project 10 Pacific Light & 

Power Kaua’I, Hawaii Kaua’I Island Utility Coop.

Total 1,375

Sources: Solar Thermal Magazine 2010; NASDAQ QMS 2006; NREL 2009; CEC 2010b; Solana Solar 2009;

Bloomberg 2009; CEC 2010b

Solar Millennium made headlines in 2011 when it decided to change its Blythe (1 GW), 

Amargosa (500 MW), and Palen (500 MW) projects from CSP troughs to PV (PV Magazine 

2011; Wesoff and Prior 2011). In doing so, Solar Millennium forfeited a DOE loan guarantee 

that was acquired to assist development of the Blythe project. Solar Millennium’s technology 

switch was reportedly due to shifting economics as PV modules and other costs have come down 

in price significantly over the past several years (Clean Energy Authority 2011a). Solar

Millennium is currently in insolvency proceedings and has sold its U.S. project pipeline to 

German developer solarhybrid.

11 

2.2 CSP Tower

2.2.1 Technology Overview

CSP tower systems, often referred to as power towers or central receivers, use a field of mirrors

called heliostats that individually track the sun on two axes and redirect sunlight to a receiver at 

the top of a tower. Sunlight is concentrated 600–1,000 times, making it possible to achieve 

working fluid temperatures of 500°–800°C (930°–1,470°F) (Australian National University

2010).

 11In March, 2012, solarhybrid began its own insolvency proceeding due to concerns of illiquidity (i.e., not enough 

cash to pay bills) (PV Magazine 2012).
8

Pilot CSP tower plants have proven the technical feasibility of using various HTFs including 

steam, air, and molten nitrate salts. Early CSP tower systems generated steam directly in the 

receiver; however, current designs use both steam and molten salt as HTFs. When integrating 

storage, CSP tower systems have an advantage over CSP troughs since they are able to obtain 

higher operating temperatures, resulting in a lower required salt inventory for the storage system

(Richter et al. 2009).

Figure 7. The Solar One facility in California employed CSP tower technology

Source: PIX 00036

Figure 6. CSP tower schematic

Source: U.S. Department of Energy 2011c
9

The largest CSP tower system currently in operation is the PS20 station, designed by Abengoa

Solar in Seville, Spain (LaMonica 2009). The 20 MW facility, which began operation in April 

2009, features a 531 foot (ft) solar tower and 1,255 heliostats. The PS20 is adjacent to the 

world’s first commercial CSP tower, the PS10, also designed by Abengoa Solar. 

In Israel, BrightSource is operating the 4–6 MW Solar Energy Development Center

(BrightSource Energy 2011b). According to BrightSource, the facility generates the highest 

quality steam of any operational solar thermal plant at a temperature of 550°C (1,022°F) and 140

bar (b) pressure. 

Also worth noting, the 23 MW Coalinga solar project in central California, recently 

commissioned in the San Joaquin Valley, utilizes a 327 ft tower system to produce steam (but no 

electricity) and improve output from an aging nearby oil field. Chevron owns the Coalinga field 

and the development company that installed the system, Chevron Technology Ventures (IBM 

2011). 

2.2.2 CSP Tower Market Overview

Some 2,655 MW of proposed CSP tower systems are currently under contract with U.S. utilities. 

BrightSource Energy has the most megawatts under contract. In April 2011, BrightSource closed 

on a $1.6 billion DOE loan guarantee for its Ivanpah, California, facility (DOE 2011c). Of 

BrightSource’s 2.2 GW portfolio under contract, Ivanpah represents 392 MW, which allocated

about evenly between PG&E and SCE. Many of BrightSource’s other projects are at undisclosed 

locations. In October 2010, BrightSource broke ground on the Ivanpah project and received a 

$300 million investment from NRG Energy. With this investment, NRG Energy will hold a 

majority equity stake in the project (Murray 2010). 

One small utility-scale CSP tower system operates in the United States—eSolar’s 5 MW Sierra 

Suntower. The facility became operational in 2009 and sells power to SCE (NREL 2010b). In 

co-development with NRG Energy, eSolar has two proposed facilities, the Gaskell Sun Tower 

phases 1 and 2, under long-term contracts with IOUs for a total of 245 MW. To help lower costs, 

eSolar deploys a modular design surrounding a conventional turbine (eSolar 2010). 

SolarReserve has two CSP tower facilities under development—Crescent Dunes and Rice Solar 

Energy Project—totaling 260 MW and 25-year contracts with PG&E and NV Energy (Reuters

2009). SolarReserve was founded by United Technologies Corp., whose Rocketdyne subsidiary 

demonstrated the solar tower technology at the Solar One and Solar Two power plants in 

southern California. However, both facilities were demonstration projects and are no longer 

operating (Solar Reserve 2010). U.S. Renewables Group, a large private equity firm exclusively 

focused on clean fuel projects, supports SolarReserve (SolarReserve 2011). 
10

Table 3. U.S. Utility-Scale Central Receiver Projects in Development

Plant MW Developer Location PPA With

BrightSource, 

PG&E PPA 108 BrightSource California PG&E

Coyote Springs 1 &

2 400 BrightSource Coyote Springs, Nevada PG&E

Crescent Dunes 110 SolarReserve Nye County, Nevada NV Energy

Gaskell Sun Tower 

(Phases 1 & 2) 245 NRG/eSolar Kern County, California SCE

Hidden Hills 1 & 2 500 BrightSource Inyo County, 

California PG&E

Ivanpah

Phases 1–3 392 BrightSource Ivanpah, California PG&E

Rice Solar Energy 

Project 150 SolarReserve Blythe, California PG&E

Rio Mesa 1–3 750 BrightSource Riverside County, 

California SCE

Total 2,655

2.3 Parabolic Dish

2.3.1 Technology Overview

Parabolic dish, or dish engine, systems are individual units comprised of a solar concentrator, a 

receiver, and an engine or generator. The concentrator typically consists of multiple mirror facets 

that form a parabolic dish, which tracks the sun on two axes and redirects solar radiation to a 

receiver (Richter et al. 2009). The receiver is mounted on an arm at the focal point of the 

reflectors and contains a motor-generator combination that operates using either a Stirling engine 

or a small gas turbine. Dish systems are generally between 10 kilowatts (kW) and 25 kW in size.

Compared with other CSP technologies, parabolic dish conversion efficiencies are the highest, 

reaching over 30% (SolarPACES 2010).

Figure 8. Schematic of a parabolic dish system

Source: DOE 2011d
11

Parabolic dish systems are considered highly modular, allowing individual deployment for 

remote applications or groupings for small-grid or large-scale utility applications (SolarPACES

2010). Individual placement also enables greater flexibility than other CSP systems since dish 

systems can be placed on varied terrain with grades up to 5% (TEEIC 2010). In addition, 

parabolic dish technology only uses small quantities of water, mostly for washing concentrators 

free of dust. However, due to current economies of scale, dish systems are generally only 

proposed in utility-scale projects. 

2.3.2 Parabolic Dish Market Overview

At present, there are no utility-scale parabolic dish projects in development.

12 Through 2010, one 

company—Tessera Solar—held at least three contracts with western U.S. utilities, representing 

more than 1,600 MW. Tessera was the development affiliate to Stirling Energy Systems, which 

was a manufacturer of parabolic dishes and Stirling solar engines before filing for Chapter 7 

bankruptcy in 2011 (Wesoff 2011).

In May 2011, Tessera lost its last contract when the developer that bought the project, AES, 

decided to replace the parabolic dish technology with PV. Greentech Media reported that Tessera 

could not secure a DOE loan guarantee and was thus unable to fulfill the contract (Wesoff 2011).

2.4 Linear Fresnel Reflector

2.4.1 Technology Overview

Linear Fresnel reflector, also referred to as compact or concentrating linear Fresnel reflector, 

systems are made up of flat or nearly flat mirror arrays that reflect solar radiation onto elevated 

linear absorbers or receiver tubes. Water, the typical thermal fluid, flows through the tubes and is 

converted into steam. Steam can also be generated directly in the solar field, eliminating the need 

for costly heat exchangers (DOE 2010b). The system is similar to a CSP trough in that the 

sunlight is concentrated in a linear fashion. However, instead of a single curved mirror, linear 

Fresnel systems concentrate the insolation of many slightly curved mirrors onto a receiver. The 

receiver is stationary and does not move with the mirrors as in the CSP trough systems, so it does

not require rotating couplings between the receivers and the field header piping, thus providing 

additional design flexibility. 

 12 In March 2011, the Export-Import Bank of the United States supplied a direct loan of $30 million to develop a 

10 MW solar dish project in Rajasthan, India. U.S.-based dish manufacturer Infina Corporation will supply the 

modules for this project (Export-Import Bank 2011).
12

2.4.2 Linear Fresnel Reflector Market Overview

In 2010, Ausra—the sole developer of linear Fresnel projects in the United States—sold its 

technology and development pipeline to the French company Areva (Baker 2010). To date, 

Areva’s 5 MW Kimberlina project in Bakersfield, California (previously developed and owned 

by Ausra), is the only utility-scale linear Fresnel reflector project in the United States. Prior to 

the Areva sale, Ausra was developing the Carrizo Energy Solar Farm, a 177 MW project, but 

that project was suspended. 

2.5 Solar-Fossil Hybrid Power

2.5.1 Technology Overview

Hybrid power plants incorporate both solar collector fields and fossil fuel combustion to generate 

power, often relying on a common steam cycle and allowing for power production during 

sunlight fluctuations and nighttime hours.13 There are many variations of hybrid plants, including 

simple natural gas backup, integrated solar combined cycle plants, and solar plants providing 

thermal input to existing or newly designed coal-fired plants. To produce steam in hybrid plants, 

CSP trough, CSP tower, and linear Fresnel collector devices may be used. Figure 10 is a 

rendering of a solar-fossil (gas turbine/CSP trough) hybrid facility. 

 13 For purposes of this report, in NREL’s database projects are designated as hybrid if at least 50% of the energy is 

expected to be derived from fossil fuels. Many CSP systems utilize a small quantity of fossil fuel but are not 

classified as hybrid systems. For example, the BrightSource Ivanpah project will utilize a small auxiliary boiler, 

which is expected to provide 2% of its output.

Figure 9. Linear Fresnel reflector schematic

Source: DOE 2011c
13

Figure 10. Rendering of a solar/fossil hybrid facility

Source: Inland Energy 2011

Combining CSP and fossil fuel power is not a new concept. In fact, many CSP plants use natural 

gas as a backup energy source. Assuming space requirements are adequate, it is possible to 

retrofit existing power plants with solar thermal technology, an option that may be advantageous 

for utilities looking to increase the efficiency of their fleets. By combining the components of 

technologically proven fossil fuel plants with the environmental benefits of CSP, there could be 

an increase in market opportunities and competition with conventional power plants.

2.5.2 Solar/Fossil Hybrid Market Overview

One solar/fossil electric generating plant, as defined by NREL, is currently in operation—the 

Martin Next Generation Solar Energy Center. The plant combines 75 MW of CSP trough with a 

3,705 MW natural gas- and oil-fired generation facility.

As shown in Table 4, two utility-scale solar/fossil hybrid plants are currently in development, the 

Palmdale and Victorville 2 projects. These two plants feature similar hybrid designs including 

CSP trough and combined cycle technology designed and constructed as a combined facility

(Inland Energy 2011). In each project, the solar field will provide approximately 10% of the 

thermal input. Both projects are also proposed to be constructed and owned by municipalities. 

The Victorville 2 project was approved by the California Energy Commission (CEC) in 2008 

(City of Victorville 2008). In August 2011, the CEC formally approved development of the 

Palmdale project (CEC 2011). 

Table 4. U.S. Utility-Scale Solar-Fossil Hybrid Projects Under Development

Plant Solar/ 

Total MW Developer CSP and Fossil Technology PPA With

Palmdale Hybrid 

Power Project 50/570 Contractor not selected yet

CSP trough/natural 

gas combined cycle

City of 

Palmdale

Victorville 2 Hybrid 

Power Project 50/513 Contractor not selected yet

CSP trough/natural 

gas combined cycle

City of 

Victorville

Solar Total 100/1,083
14

A large solar hybrid project, the San Joaquin 1 and 2 facilities, was recently cancelled due to 

“issues regarding project economics” and other aspects of the project (Martifer Renewables

2010). Additionally, the 4 MW Cameo hybrid demonstration project in Grand Junction, 

Colorado, was recently decommissioned and dismantled. Cameo was the first power plant to 

hybridize solar troughs and coal-fired generation.

2.6 Thermal Energy Storage 

TES provides the ability of a system to store thermal energy collected by a solar field in a 

reservoir for conversion to electricity at another time. For CSP technologies, storage can be used

to balance energy demand between day and night or during times of intermittent sunlight. By 

oversizing the solar fields and pulling the excess heat to the thermal storage component, the 

turbine can operate at a fairly constant rate. Figure 11 illustrates this process. 

A storage system enables CSP plants to (1) negate the variability in system output due to sudden 

shifts in the weather and (2) extend the range of operation of a CSP system beyond daylight 

hours (Biello 2009). The power produced throughout the day can be more effectively matched 

with energy demand, therefore increasing the value of the power as well as the total useful power 

output of the plant at a given maximum turbine capacity. 

A well-located CSP trough plant with no fossil backup or thermal storage should be able to 

achieve a 25% annual capacity factor (NREL 2011a). CSP with storage is theoretically capable 

of capacity factors around 75%, although economic application of storage limits the capacity 

factor to approximately 50% given current available technology.

14 CSP generation facilities 

supported through the DOE loan guarantee program have capacity factors that range from 26%–

28% for projects without thermal storage to 43%–52% for projects with thermal storage (DOE 

2011c).

 14 Capacity factor represents the delivered energy production divided by the theoretic energy production if the plant 

operated at full output all the time.

MW

Max Solar 

Energy

Solar Thermal Storage

Generating 

Capacity

From Storage

Time of Day

Solar Energy

Generation

Thermal Storage 

To Storage

Figure 11. Solar thermal storage extends the power production period
15

2.6.1 Technology Overview

Storage mechanisms are classified as either direct or indirect based on how the storage medium 

is heated by the solar concentrators. Indirect systems, such as most CSP trough plants, use a 

separate HTF, such as synthetic oil, that passes through a heat exchanger to heat the storage 

medium. Direct systems use the same fluid, such as steam, for both the HTF and the storage fluid 

eliminating the need for expensive heat exchangers.

Figure 12. The Solar Two system in California included a thermal energy storage system

Source: PIX 02185

Molten salt storage systems, which can be used in direct or indirect storage systems, seem to 

hold the greatest promise of economic commercialization (Price 2009). Molten salt systems 

allow the solar field to operate at higher temperatures relative to other fluids or storage media, 

reducing the cost of the system. Because salts melt at very high temperatures (e.g., ordinary table 

salt melts at around 1,472°F), they can hold significant quantities of heat without vaporizing 

(Biello 2009). A mixture of sodium nitrate and potassium nitrate, the salts can efficiently return 

as much as 93% of the energy sent into storage.

However, a technical disadvantage of molten salts is that they freeze at relatively high 

temperatures, from 120°–220°C (250°–430°F). Sandia National Laboratories is currently 

developing new salt mixtures with the potential for lower freezing points below 100°C (212°F)

to help solve this challenge (Biello 2010).
16

2.6.2 Thermal Energy Storage Market Overview

TES offers potential long-term cost advantages for CSP plants by amortizing the fixed cost of the 

power block over greater electricity generation. However, a lack of development and operational 

experience has limited technology use to date.

The Andasol plant in Spain, developed by Solar Millennium, utilizes 28,500 metric tons of 

molten salt to provide 7.5 hours of backup generation at full output (Solar Millennium 2010). 

The salt utilized in the plant is 60% sodium nitrate and 40% potassium nitrate, both commonly 

found in fertilizers and other materials. 

In the United States, no operating CSP plants utilize thermal storage, although several are in 

development. Abengoa Solar’s Solana power station is expected to store 6 hours of thermal 

energy (NREL 2010a). Located outside Gila Bend, Arizona, the 250 MW (net)15 facility is 

projected to cost $2.00 billion, $1.45 billion of which will be paid for with debt financing

covered under a DOE loan guarantee (Prior 2010). In late 2011, BrightSource announced that it 

will add storage capability to three of its PPAs with SCE (BrightSource Energy 2011a).

16

Bell Independent Power Corporation (Bell) is also developing a CSP and combined thermal 

storage facility. The 5 MW plant will be part of the new Tech Park in Tucson, Arizona

(Environmental Leader 2010), and was the result of Bell’s request for proposal submission to

Tucson Electric Power (TEP). Bell and TEP signed a 20-year contract, which is currently 

awaiting approval from the Arizona Corporation Commission (Solar Thermal Magazine 2010). 

The facility is expected to begin operating in 2012.

 15 Because the generator size will be smaller than actual capacity after the application of storage, these 250 MW are 

a “net” figure.

16 According to a BrightSource press release, “Under the original power purchase agreements with Southern 

California Edison, BrightSource would provide approximately four million megawatt-hours of electricity annually 

across seven power plants. Due to higher efficiencies and capacity factors associated with energy storage, the new 

set of agreements will provide approximately the same amount of energy annually but with one less plant, reducing 

the land impacts of delivering this energy and avoiding transactional costs that ultimately impact California’s 

ratepayers” (BrightSource Energy 2011a, p. 2).
17

2.7 Cooling Systems

Steam-driven power plants, such as CSP facilities, require a consistent source of fresh water,

which can be difficult to obtain in the desert where the solar resource is plentiful. Water 

consumption is primarily connected to the cooling system. There are three primary types of 

cooling systems: open loop, closed loop, and dry. Open loop, or once-through, cooling systems 

pull heat from the power plant by withdrawing large quantities of water from rivers and other 

sources and returning the now-warmer water to its source. As most of the water used in an open 

loop system is returned to its source, these systems actually consume (via evaporation) very 

small quantities of water (DOE 2008). 

A Discussion on Capacity Factors

Capacity factor is the ratio of actual output of power over a period of time compared to 

the output of full nameplate capacity operation. Solar technologies have relatively low 

capacity factors because they only produce power when the sun is shining. Other 

technologies, such as coal or natural gas, can produce power at a relatively constant rate 

or as dictated by demand. 

Figure 13. Comparison of capacity factor by technologies

The capacity factor for PV technologies ranges from 14%–18% for thin-film systems and 

20%–24% for crystalline installations. Thermal storage can significantly increase the 

capacity factor of eligible CSP plants from 25% without storage to approximately 75% 

with storage.

Source: Renewable Energy Research Laboratory 2011

0%

20%

40%

60%

80%

100%

Capacity Factor Range
18

Due to environmental concerns associated with increasing the temperature of river water, open 

loop systems were disallowed in new power generation facilities in the early 1970s (California 

Environmental Protection Agency 2008). Nonetheless, open loop cooling systems grandfathered 

into the new law are still widely used throughout the United States. According to the DOE, more 

than half of the existing fleet of thermal generating plants in the United States are estimated to be 

equipped with once-through cooling systems (DOE 2008). The U.S. Environmental Protection 

Agency is in the process of developing new rules associated with Section 316(b) of the Clean 

Water Act that will help determine when open loop cooling will be allowed. Recent revisions to 

the draft rules gave power developers more flexibility in water cooling, although some may still 

need to switch from open to closed loop systems.

Table 5. Water Usage Requirements for Electric Generation Technologies

Cooling System Power Plant Technology Water Usage (Gallons/MWh)

Withdrawal Consumption

Open loop Fossil/biomass 

waste/nuclear steam 20,000–60,000 100–400

Natural gas combined cycle 7,500–20,000 50–100

Closed loop

Fossil/biomass waste 

steam 300–600 300–1,100

Nuclear 500–1,100 700–850

Geothermal 2,000 1,400

Solar trough 760–920 720–1,050

Solar tower 750 740–850

Dry Various technologies 0 0–80

Hybrid Various technologies 50–650 100–600

Source: DOE 2008; Macknick et al. 2011

Closed loop cooling systems cool and recirculate water within the power plant and thus withdraw 

far less water than open loop systems. However, during the cooling process, water is lost via 

evaporation. Closed loop systems negate thermal pollution of water sources and withdraw far 

less water but lower plant efficiency by approximately 0.8%–1.4% (DOE 2008). 

Dry cooling, or air cooled, systems use air to condense heat and cool power plants. These 

systems have minimal water requirements—either in withdrawal or consumptive modes—and 

can generally be used in all steam cycle power plant technologies, including CSP trough and 

CSP tower facilities (DOE 2008). However, dry cooling systems are more expensive to build and 

can lower the efficiency and output of the power plant, especially on very hot days. 

To help balance cost, plant output, efficiency, and water use, some power plants are being 

designed with hybrid cooling systems that combine closed loop wet and dry cooling systems 

(DOE 2006). Air cooling dissipates heat directly into the air, using water only for general plant 

uses and steam cycle blowdown, which eliminates dissolved solids in the steam. Hybrid cooling 

systems can reduce water use by 50%–85% with only a 1%–3% drop in power output (DOE 

2010a). 
19

3 Photovoltaic Solar Power

In the last several years, solar PV has achieved unprecedented scales of deployment. A range of 

factors have contributed to this development, including a rapid decline in solar module prices, 

increased requirements on utility procurement of renewable energy via state RPS programs, and 

financial incentives available through the federal government. Total installed PV capacity has 

increased from 22 MW in 2000 to nearly 3.1 GW as of the third quarter of 2011 (SEIA 2011b). 

Over 1 GW of grid-tied PV was added in the first three quarters of 2011 alone. 

Utility-scale installations have seen the greatest growth in the last two years, increasing from 

70 MW installed in 2009 to over 700 MW installed in 2011 (SEIA 2011b; SEIA 2012). In 2011 

alone, utility installations were up 185% from the previous year. Going forward, NREL estimates 

that there are more than 11 GW of utility-scale PV projects in the pipeline with signed PPAs as 

of January 2012. 

3.1 Traditional PV

3.1.1 Technology Overview

PV systems consist of c-Si or thin-film solar modules. c-Si materials include monocrystalline or 

polycrystalline cells. Thin-film PV includes an array of materials including CdTe, copper indium 

gallium selenide (CIGS), and a-Si. These materials are generally less expensive to produce than 

c-Si but have lower conversion efficiencies.

17 Although many thin-film materials have been 

introduced over the past several years, steep price reductions in c-Si modules have overridden 

the technology’s cost advantage. 

 17 Solar panel efficiency is the ratio of electric power produced by a PV module to the power of the sunlight striking 

the module.

Figure 14. SunEdison's 8.2 MW Alamosa plant

Source: PIX 15558
20

The majority of PV modules—about 80%–90%—currently installed in the United States are 

based on c-Si wafers (Solarbuzz 2010).

18 Silicon wafers are produced either by slicing sections 

of bulk silicon or growing thin ribbons that are sectioned into wafers (Bates 2000). Since silicon 

has a high melting point, the production process is energy intensive. In addition, much of the 

bulk material is lost when cutting the wafers. 

Several companies have attempted to innovate on the process of silicon production to eliminate 

this waste and hasten the production process as well. For example, 1366 Technologies, a solar 

cell manufacturer based in North Lexington, Massachusetts, has devised a continuous process 

that uses a molten silicon bath to form wafers instead of the traditional ingots and boules. The 

company secured a $150 million loan guarantee from the DOE in September 2011 to scale up 

manufacturing and had secured two prior DOE grants to pioneer the technology. The molten 

silicon process is estimated to achieve production cost reductions of 50%, energy use reductions 

of 90%, and the generation of silicon wafers in a fraction of the time of current production 

standards (DOE 2011a). 

Before the end of 2008, the demand for crystalline solar panels outpaced the industry’s ability to 

produce them, a trend that opened the door for other solar module alternatives, such as thin films 

(Wang 2009b). Manufacturing c-Si has since ramped up, and as of 2011 it appears to have 

outpaced demand.

PV arrays require inverters to convert direct current (DC) power produced by the modules into 

alternating current (AC), which can then be connected to the electrical grid. Throughout the 

components of the system there are electrical losses, which derate the conversion from nameplate 

DC power rating to AC power rating (as explained in Table 6). 

 18 This includes installations at the residential, commercial, and utility scale. If only utility-scale installations (as 

defined by this report) are considered, then the figure is approximately 58%, according to NREL’s internal 

databases.
21

Row spacing is very important in order to maximize power density (kW/acre) and minimize 

panel shading. If only a portion of a cell, panel, or array is shaded, the power output can fall—

sometimes dramatically.

19 In contrast to CSP technologies, which require direct sunlight to 

operate properly, PV systems utilize both direct and indirect (diffuse) radiation (Pitz-Paal 2009). 

For this reason, PV systems can be more widely deployed and can even operate on cloudy days

(albeit at a lower capacity). Under cloudy weather and dawn and dusk conditions, thin-film solar 

panels convert low and diffuse sunlight to electricity more efficiently than crystalline-based 

panels. 

Current PV conversion efficiencies vary by technology and manufacturer, though generally 

speaking, thin-film materials have lower efficiencies than silicon wafers. First Solar, who deals 

 19 The installation of micro-inverters on each module can recover 10%–30% of annual performance loss due to 

shading. This has proven a more efficient approach to DC/AC conversion than the installation of one central inverter 

(Deline et al. 2011). 

Derate Factors for Photovoltaic System Components

Table 6. PVWatts Default Derate Values

The overall DC-to-AC derate factor varies for different PV systems and 

applications. NREL’s PVWatts tool incorporates a standard derate factor 

of 0.77 (or a 23% loss in output from nameplate DC rating to actual AC 

energy produced). 

Source: NREL 2011b

Component Derate 

Factors PVWatts Default Range

PV module nameplate 

DC rating 95% 0.80–1.05

Inverter and transformer 92% 0.88–0.98

Mismatch 98% 0.97–0.995

Diodes and connections 100% 0.99–0.997

DC wiring 98% 0.97–0.99

AC wiring 99% 0.98–0.993

Soiling 95% 0.30–0.995

System availability 98% 0.00–0.995

Shading 100% 0.00–1.00

Sun-tracking 100% 0.95–1.00

Age 100% 0.70–1.00

Overall DC-to-AC derate 

factor 77% 0.09999–0.96001
22

exclusively in CdTe modules, reported an average efficiency of 11.7% in 2011 (up from 11.4% 

in 2010) and recently announced a record-setting 14.4% for their highest efficiency module (First 

Solar 2012). Modules in the c-Si space run between 14% and almost 20%20 efficiency in the 

field, with 23% efficiency achieved in controlled laboratory testing (referred to “championproduction” efficiency) (Green et al. 2011).

PV systems do not require water to operate. However, a small amount of water is needed to clean 

the panels and is recommended in areas that have little rain. Operation and maintenance costs are 

minimal for these systems because there are few moving parts and no need to service turbines or 

generators (see Figure 17). The largest cost of PV technology is for the modules, approximately 

50% of the total, followed by the installation materials, labor, and the inverters. Inverter 

replacement can be a significant expense. PV module warranties are generally 20–25 years long; 

however, inverter warranties are typically 10–15 years long (Russell 2010). Technological 

improvements are occurring rapidly in many subsectors. For example, microinverters can be

paired with each PV module, in contrast to centralized inverters, which are paired with a bank of 

modules. Therefore, if a single microinverter fails, only the module paired to the failed inverter is 

affected (Russell 2010). 

There is concern about the life of both microinverters and centralized inverters. Improvements 

are being made in this area, too. For instance, in October 2010, SolarBridge Technologies 

announced a 25-year warranty on its new microinverter, the SolarBridge AC Module System 

(SolarBridge 2010). 

 20 SunPower’s E19/425 solar panel has a reported conversion efficiency of 19.7%, one of the highest in the PV 

market today (SunPower 2010).
23

3.1.2 PV Market Overview

The PV industry’s extraordinary growth has not been without challenges. From the overheating 

and contraction of the Spanish market in 2007 and 2008 (the result of miscalculations in their 

feed-in tariff program) to plummeting module prices, the solar industry has proven a very 

dynamic market. Many companies have downsized or withdrawn completely from the market. 

Between late 2008 and 2011, several PV manufacturers and developers, including OptiSolar, 

SunPower, SunTech Power Holdings, Energy Conversion Devices, Solyndra, and SunEdison, 

laid off workers or shuttered operations (Baker 2009; Fehrenbacher 2009; Wang 2010). 

Despite this challenging landscape, solar industry job growth in the United States has been 

significant over the last several years. The most recent Solar Jobs Census estimates that as of 

August 2011, there were 100,237 solar employees (workers who spend over 50% of their time 

supporting solar-related activity), which is up 6.8% from August 2010 (Solar Foundation 2010). 

To analyze the utility-scale market, this report segments PV into three general project sizes. 

Systems smaller than 20 MW are commonly referred to as “distributed” systems, as they often 

Cost of PV Facility by Components 

Figure 15. Utility-scale PV facility by cost component

Source: Goodrich et al. 2012

Figure 15 shows the cost breakdown for a fixed-tilt utility-scale PV system

utilizing c-Si modules. Lower efficiency thin-film modules generally cost less 

but can have higher balance of plant (or non-module) expenses. This includes 

costs for supporting structures, DC cabling, and inverters. 

$0.00

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

$3.50

$4.00

Installed Cost ($/ watt)

Other

Sales tax

Grid integration

Installation labor

Installation materials

Inverter

Module
24

tie into distribution level voltages.21 Systems 20–49 MW are referred to as “mid-sized,” and 

those 50 MW and larger are referred to as “large-sized.” 

3.1.2.1 Distributed Utility-Scale PV Systems

Distributed systems are often integrated into the distribution grid interconnecting below 

69 kilovolts, which is generally considered the level at which transmission service begins 

(Wisconsin Public Service Commission 2009). However, for several reasons these systems are 

applicable for consideration as utility-scale systems and were therefore included in this analysis. 

At this project size, power is almost exclusively sold to utilities. Most customers do not have the 

load to support 5 MW or more of on-site PV.22 In addition, in order for solar projects to access 

relatively low-cost capital, the PPA contract must be signed with a counterparty that has an 

excellent credit rating (Feo and Tracy 2009). Utilities are generally considered excellent 

counterparties due to their bonding capability and regulatory mission to provide power to their 

customers.23 Appendix Table B-1 represents all distributed utility-scale (5.0–19.9 MW) projects 

currently under development that hold PPAs.

PV project development at the distributed utility-scale has many advantages. Environmental 

permitting, grid integration, and site control can be less burdensome at this project size. Certain 

companies are also considering development at brownfield sites, including former mining 

operations and other disturbed lands, which can further reduce environmental oversight of 

project development (Mendelsohn 2010). 

In California, generators up to 20 MW are subject to the Small Generator Interconnection 

Procedures (SGIP), which avoids the need to be grouped into a “cluster” for a time-consuming, 

grid-wide system impact study. However, this shortcut has attracted a lot of projects just under 

the threshold, requiring the California independent system operator (ISO) to reassess the SGIP 

(Mendelsohn 2010).

According to NREL’s internal database, approximately 65 distributed projects totaling 

589.2 MW of capacity are currently under development and hold PPAs. See Appendix Table B-1 

for information on these projects. 

3.1.2.2 Mid-Sized Utility-Scale PV Systems

In the past few years, many announcements regarding PV systems in the 20–49 MW range have

been made. The first two systems in this size range were completed in 2009: the 25 MW DeSoto 

and the 21 MW Blythe projects. Prior to these projects, the largest system in the United States 

was the 14 MW Nellis Air Force Base system. As shown in Appendix Table B-2, there are 

currently 57 mid-sized projects in advanced development (i.e., with PPAs in place) totaling 

 21 For more information, visit www.recurrentenergy.com/solar/. 22 Further, large customers pay for power primarily through demand charges tied to their peak demand during the 

month (and often with a “ratchet” mechanism tied to the peak demand in the prior 12-month period). Accordingly, 

due to the variable output of a solar field, utility charges may not decline proportionately with solar production, 

although the energy component of the utility bill should decline proportionately with solar production.

23 Regulatory decisions to limit rate increases can negatively impact bond ratings and the utility’s ability to countersign renewable energy contracts or develop renewable energy projects. The importance of a utility’s 

creditworthiness is discussed in greater length in the second report, Finance and Government Initiatives

(Mendelsohn et al. 2011).
25

1,329.5 MW of capacity. SCE leads all utilities in this size category with 18 contracts totaling 

384 MW. See Table B-2 for more information on these projects. 

According to NREL’s database of project announcements, First Solar deploys its own CdTe thinfilm panels in its projects. First Solar CdTe modules have been selected for other projects, 

including juwi solar’s BlueWing facility in Texas (Vo 2010). Most other projects are expected to 

utilize c-Si panels, although the panel manufacturer and even the PV material are not always 

disclosed as part of the project announcement. In part, this may be because developers wait to 

procure the lowest-cost components available until just prior to installation. 

3.1.2.3 Large-Sized Utility-Scale Systems 

According to NREL’s utility-scale projects, there are currently 9,425 MW of large-sized (greater 

than 50 MW) PV projects currently holding a PPA with a utility purchaser (see Table B-3). None 

are currently operating. First Solar is the clear leader among developers with 1,920 MW of 

capacity in the development or construction phase. This amounts to about one-fifth of the total 

capacity of large-sized projects under development. First Solar also has one of the largest 

projects under current development, the 550 MW Topaz Solar Farm, which will sell its energy to 

PG&E (Wang 2009). For purposes of comparison, the Topaz project is 10 times larger than the 

largest PV project completed in the United States: the recently completed 55 MW Copper 

Mountain Solar Facility in Nevada (which also uses First Solar’s CdTe panels).

SunPower is another player with a significant stake in the large-sized solar project space. The 

developer signed three PPAs with SCE in 2011 for the sale of 711 MW of power from three 

facilities. These three projects represent all of SunPower’s plays in the large-sized category.

Energy developer enXco recently signed an agreement with Japanese manufacturer Solar 

Frontier to deliver up to 150 MW of CIS24 panels for use in enXco’s PPAs with SDG&E. These 

will be the first CIS modules deployed at utility scale in the United States.

Many more utility-scale solar projects than those listed here have been proposed but do not 

necessarily have a PPA contract in place. California alone has tabulated over 70,000 MW of 

proposed renewable energy projects for the state, over 90% of which are projected to be 

200 MW and larger (CEC 2010b). 

 24 CIS is a variant of copper-indium-gallium-diselenide, often referred to as CIGS.
26

3.2 Concentrating PV

3.2.1 Technology Overview

CPV systems use optic lenses to focus sunlight onto high-efficiency solar cells. Due to the 

integration of lenses, CPV systems require direct sunlight to operate, so most systems employ 

single- or dual-axis trackers to follow the sun across the sky (BLM 2010). 

CPV technologies combine two components to generate electricity: concentrators, which can be 

either lenses or mirrors, and a semiconducting material based on the array of available PV 

Development on Public Lands

Many large-scale solar projects, including those without PPA contracts, have been proposed for 

development on federal land administered by the U.S. Department of the Interior’s Bureau of 

Land Management (BLM). Interior Secretary Ken Salazar announced several initiatives to 

improve the speed of BLM application review. In 2009, there were 470 applications, with 158

of those being solar, to develop 97,000 MW of renewable energy projects on BLM land (U.S. 

Department of the Interior 2009). Federal agencies were to work with western leaders to 

designate tracts of BLM land as suitable for large-scale solar energy development, fund 

environmental studies, open new solar energy permitting offices, and speed reviews of industry 

proposals (U.S. Department of the Interior 2009). 

For several years, the BLM has been involved in a wide-scale environmental evaluation of solar 

energy development across BLM lands. The process, referred to as the Solar Programmatic 

Environmental Impact Statement (PEIS), was expanded to review 24 solar energy study areas. 

In October 2009, the BLM issued over 1,100 pages of comments that will be considered when

developing the draft PEIS (BLM 2010). 

In June 2010, the BLM issued a guidance document on the rental fees to be applied to solar 

facilities for use of BLM land. The BLM will apply two separate rental fees: (1) base rent, 

which is applied on a per-acre basis to specific counties and ranges from $15.70/acre/year to 

$313.88/acre/year; and (2) megawatt capacity fee, which is applied on a per-megawatt basis and 

ranges from $5,256/MW/year for PV projects to $7,884/MW/year for CSP with 3 hours or more 

of thermal storage (BLM 2010). In January 2011, BLM issued a solar energy plan of 

development, which provides guidance on submitting solar applications to the agency, including 

outlining expected information with respect to facility engineering, project construction, and 

transmission interconnection (BLM 2011). 

One project of note on BLM land is BrightSource Energy’s Ivanpah Solar Project. The Ivanpah 

site is home to the desert tortoise, classified as “threatened” on the endangered species list 

(Wesoff 2011b). Construction at the Ivanpah site was halted in April 2011, and after further 

analysis, was allowed to resume in June 2011. According to a report submitted to the BLM and 

the CEC, 20 live tortoises were observed to be living within the project boundary (Solar Power 

Partners 2010). BrightSource was required to mitigate the environmental impact of the project 

by significantly reducing the overall footprint. Environmental oversight will remain over the 

project’s life and, likely, beyond. 
27

technologies. Depending on a selected strategy, a manufacturer will employ a combination of 

concentrators and semiconducting material to achieve the lowest cost of energy.

The potential cost advantage of CPV over traditional PV is the use of less semiconducting 

material that comprises the cell. Lower efficiency CPV technologies may employ silicon (CdTe 

and CIGS can also be used), but the highest efficiencies are achieved with multi-junction cells 

using materials other than silicon. Field efficiencies for these cells are in the 30% range and 

laboratory tests have achieved upwards of 40% efficiency (Kurtz 2011). 

Current concentration intensities range from as low as 2x (or 2 “suns”) to as high as 500x. Some 

emerging technologies are anticipated to reach up to 1,000x. CPV concentrations are often 

distinguished as low, medium, and high as roughly outlined in Table 7. Because of the high 

temperatures inherent to light concentration, CPV systems often require integration of heat sinks 

to dissipate heat and prevent damage to the solar cells.

Table 7. CPV Concentration Classes

Class of CPV Typical Concentration 

Ratio Type of Converter

High-concentration >400X Multi-junction

Medium-concentration ~3X–100X Silicon or other cells

Low-concentration <3X Silicon modules

CPV systems function similarly to PV systems in that they utilize inverters to convert the DC 

generated by the solar cells to AC, which can then be delivered to the electrical grid. These

systems have low water requirements and, due to their high power density, have lower land 

requirements than other solar technologies. In addition, CPV technologies have the potential to 

significantly reduce costs because the majority of the system expense is in the lenses, mirrors, 

and tracking equipment—components that are highly susceptible to economies of scale. 

3.2.2 CPV Market Overview

CPV systems are the least commercially deployed of the PV technologies. The only utility-scale 

plant currently in operation is a 5 MW project located in Hatch, New Mexico, commissioned in 

June 2011. NextEra Energy Resources owns the project, which uses Amonix modules—highefficiency, multi-junction gallium indium PV cells covered with Fresnel lenses (Clean Energy 

Authority 2011b). Amonix is one of two manufacturers currently supplying technology to the 

utility-scale CPV market in the United States; the other is French semiconductor company 

Soitec.

25 All systems are considered high concentration.26

 25 Another CPV manufacturer, Solfocus, has installations in the United States, but none are utility scale as defined in 

this report.

26 Low and medium concentrating systems may soon be competitive as well. For example, in late 2011 SunPower 

entered the CPV market with the rollout of their C7 Tracker system. This technology uses parabolic mirrors instead 

of lenses to concentrate sunlight, and monocrystalline silicon cells instead of multi-junction cells. The company has 

not yet contracted this technology for any utility-scale projects, though a 1 MW installation is planned at Arizona 

State University’s Polytechnic campus (Clean Energy Authority 2012).
28

The limited commercial success of CPV to date is partly due to the fact that these systems are 

more complex than PV systems. During 2008, as silicon prices were reaching new market highs, 

CPV systems appeared ready for a commercial breakthrough (Barron 2008). Prices have since 

collapsed, however, and this has changed the economics of several alternative technologies,

including CPV (Hamberg 2011). 

Despite the dramatic decreases in silicon and conventional module pricing, the CPV market 

looks to be entering a tentative growth stage. According to NREL’s database, at least 10 utilityscale CPV projects representing about 471 MW are currently in development and hold long-term 

PPAs with utilities. San Diego Gas and Electric (SDG&E) holds the majority of these PPAs, 

both in terms of megawatts (410 MW, or 86% of total) and absolute numbers (6). 

One CPV project, the 30 MW Alamosa Solar Generating Project in Colorado, will be the largest 

CPV installation in the world when completed in 2012 (Pankratz 2011).

27 Project developer 

Cogentrix received a DOE loan guarantee of $90.6 million in September 2011; this was the only 

loan guarantee awarded to a CPV project.

Continued market growth for CPV will be the most important factor in keeping its costs 

competitive with traditional PV and with fossil fuels. Without manufacturing in the tens of 

megawatts per year, it is unlikely that CPV will achieve the cost reductions necessary to make it 

an economic technology, despite its high efficiencies (Kurtz 2011). 

 27 There are larger CPV projects in development, but none are expected to be completed as soon as the Alamosa 

Project.

Figure 16. CPV modules at the SolarTAC testing facility in Aurora, Colorado

Source: PIX 19186
29

Table 8. CPV Systems Under Development

Facility Name Capacity (MW) Developed By Location Power Sold To

Alamosa Solar 

Generating Project 30 Amonix/Cogentrix Near Alamosa, Colorado Xcel Energy

Desert Green Solar 

Farm 6.5 Soitec Borrego Springs, California SDG&E

Imperial Solar Energy 

Center West 250 Tenaska Solar Ventures

Imperial County, 

California SDG&E

LanEast Solar Farm 22 Soitec Boulevard, 

California SDG&E

LanWest Solar Farm 6.5 Soitec Boulevard, 

California SDG&E

Littlerock Solar Power 

Generation Station 5 Amonix Torrance, California SCE

Lucerne Solar Power 

Generation Station 14 Amonix Lucerne Valley, California SCE

Rugged 80 Soitec Boulevard, 

California SDG&E

South Swan Solar 

Project 12 Amonix Swan Road Quarry, Arizona TEP

Total 471 MW
30

4 Summary of Market Highlights

Utility-scale solar capacity additions have grown exponentially in the last several years, and the 

development pipeline ensures that significant growth will maintain through the near-term. 

Plunging PV costs have altered the competitive landscape amongst technologies but have 

generally improved project economics enabling large-scale solar deployment. Key observations 

from this report include: 

• PV leads the utility-scale solar market for projects under development with 

approximately 72% of the capacity under long-term contract. In contrast, only about 

57% of the current operational capacity in the United States derives from PV 

technologies. About 71% of PV projects under development have indicated or are 

expected to utilize c-Si modules made from a wide variety of manufacturers; 

approximately 23% are contracted to use CdTe modules, most of which will be 

manufactured by First Solar.

• California utilities are priming the market by signing large PPA contracts with utilityscale developers. Combined, California’s three IOUs represent 72% of the total 

utility-scale market in the United States. 

• Though CSP trough plants dominate the CSP market today, there is nearly half as 

much CSP trough capacity in development as that for CSP tower. The contraction of 

the CSP market is largely due to the exit of Solar Millennium, who announced in late

2011 that they would be switching the technology for their Blyth and Palen facilities 

from troughs to PV.

• Conversely, CSP tower technologies have risen to prominence in the U.S.

development pipeline, representing approximately 2,655 MW, or 16% of planned 

utility-scale solar capacity. One company, BrightSource, dominates this space, with 

about 2.2 GW of projects contracted with two of California’s IOUs (SCE and PG&E).

• Currently, there are no utility-scale linear Fresnel or parabolic dish systems 

contracted for development. The principal developers of both technologies, Ausra and 

Stirling Engine Systems, respectively, have met financial troubles that have disrupted 

their development pipelines. Ausra sold its linear Fresnel technology to French 

conglomerate Areva in 2010, and Stirling declared bankruptcy in September 2011.

• CPV technologies have made big gains in the development market, with nine projects 

totaling 471 MW currently under contract. This is notable for a technology that has 

only enjoyed a few years of commercialization.
31

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41

Appendix A: Operating Utility-Scale Solar Plants

Table A-1. Operating Utility-Scale PV Plants

Plant MW Developer Operating 

Year

Solar 

Tech Location PPA With

Aerojet 5 Solar Power Inc. 2010 c-Si Sacramento, 

California

Aerojet 

Superfund 

Site

Agua Calliente

(partial output) 30 First Solar 2012 CdTe

Yuma 

County, 

Arizona

MidAmerican 

Energy 

Holdings 

(Buffett)

Air Force 

Academy 5 SunPower 2011 c-Si

Colorado 

Springs, 

Colorado

Alamogordo 

Solar Energy 

Center

5 First Solar 2011 CdTe Deming, 

New Mexico PNM

Alamosa Solar 

Plant 7 SunEdison 2007 c-Si Hooper, Colorado Xcel Energy

Avenal Solar 

Generating 

Facility

45 NRG 2011 a-Si Avenal, 

California PG&E

Blue Wing Solar 

Project 14 juwi 2010 CdTe

San 

Antonio, 

Texas

CPS Energy

Blythe 

Generating 

Facility

21 First Solar/NRG 2009 CdTe Blythe, 

California SCE

CalRenew-1 5 Meridian Energy 2010 a-Si Mendota, 

California PG&E

Cimarron I 30 First Solar 2010 CdTe Cimarron, 

New Mexico

Tristate 

Generation 

and 

Transmission

Copper Mountain 48 Sempra 

Generation 2010 CdTe

Boulder 

City, 

Nevada

PG&E

Cotton Center 

Solar Plant 17 Solon 2011 c-Si Gila Bend, Arizona APS

Davidson County 

Solar 16 Sun Edison 2011 c-Si

Cotton 

Grove 

Township, 

North 

Carolina

Duke Energy

Deming Solar 

Energy Center 5 First Solar 2011 CdTe Deming, New Mexico PNM

Desoto Solar 

Energy 25 SunPower 2009 c-Si Arcadia, Florida FPL

Dover SUN Park 10 SunPower/LS 

Power 2011 c-Si Dover, Deleware

Delmarva 

Power
42

Plant MW Developer Operating 

Year

Solar 

Tech Location PPA With

El Dorado Energy 

Solar 10 First 

Solar/Sempra 2008 CdTe

Boulder 

City, 

Nevada

PG&E

Exelon City Solar8 SunPower 2010c-Si Chicago, Illinois Exelon Corp.

Five Points 

Station 15 Solon 2011

c-Si Five Points, California PG&E

FRV Webberville 

Plant 30

Fotowatio 

Renewable 

Ventures

2011c-Si Webberville, Texas

Austin 

Energy

Greater Sandhill I 18 SunPower 2010c-Si Mosca, Colorado Xcel Energy

Hatch Solar 

Energy Center

5 NextEra/Amonix 2011 CPV Hatch, New Mexico

El Paso 

Energy

Jacksonville 

Solar 12 juwi 2010 CdTe Jacksonville, Florida

Jacksonville 

Electric 

Authority

Las Vegas Solar 

Energy Center

5 First Solar 2011 CdTe Las Vegas, New Mexico PNM

Long Island Solar 

Farm LLC 32 BP Solar 2011

c-Si Upton, 

New 

York

Long Island 

Power 

Authority

Los Lunas Solar 

Energy Center

5 First Solar 2011 CdTe Los Lunas, New Mexico PNM

Mesquite Solar 1 42 Sempra 

Generation 2011

c-Si Arlington, Arizona PG&E

Nellis Solar 12 MMA Renewable 

Ventures 2007

c-Si Nellis AFB, Nevada Nellis AFB

Paloma Solar 

Plant 17 First Solar 2011 CdTe Gila Bend, Arizona APS

Paradise Solar 

Energy Center

5 NextEra Energy 

Resources 2010

c-Si

West 

Deptford, 

New Jersey

Porterville5 Cupertino 

Electric 2011

c-Si Porterville, California SCE

Road Runner 

Solar Electric 

Facility

20 NRG Energy 2011 CdTe

Santa 

Teresa, New Mexico

El Paso 

Electric

San Luis Valley 

Solar Ranch 30 Iberdrola 2011

c-Si

Alamosa 

County, ColoradoXcel

SFPUC Sunset 

Reservoir

4 Recurrent 

Energy 2010

c-Si

San 

Francisco, California

Sunset 

Reservoir

Space Coast 

Solar Energy 10 SunPower 2010

c-Si Titusville, Florida FPL

SPS - Dollarhide 10 SunEdison 2011c-Si Dollarhide, New Mexico SPS

SPS - Hopi 10 SundEdison 2011c-Si Hopi, New Mexico SPS

SPS - Jal 10 SunEdison 2011c-Si Jal, New Mexico SPS
43

Plant MW Developer Operating 

Year

Solar 

Tech Location PPA With

Stanton Solar 

Farm 5 Regenesis 

Power 2011 c-Si

Orange 

County, 

Florida

PG&E

Stroud Solar 

Station 20 Cupertino Electric 2011 c-Si Helm, California PG&E

Westside Solar 

Station 15 Constellation Energy 2011 c-Si Five Points, California PG&E

Wyandot Solar 10 juwi 2010 CdTe

Upper 

Sandusky, 

Ohio

American 

Electric 

Power Co.

Total 673
44

Appendix B: Utility-Scale Solar PV Projects Under Development28

Table B-1. Distributed Utility-Scale PV Systems in Development (< 20 MW)

Plant MW Developer or 

Owner

Solar 

Tech Location PPA With

Austin Energy PV 5 PV Texas Austin Energy

Boron Solar Plant 15 Boron Solar, 

LLC PV California SCE

Campbell Industrial Park 

Solar Project 5 Axio Power Inc. PV Hawaii Hawaiian Electric Company, Inc.

Canton Landfill Solar 

Facility 5.6 PV Massachusetts NSTAR

Cascade Solar Project 18.5 Axio Power 

Inc. PV California SCE

Catawba County Solar 

Project 5 Strata Solar LLC PV North Carolina Duke Energy Carolinas, LLC

Celina Renewable 

Energy Center 5 SolarVision LLC PV Ohio City of Celina

Central Antelope Dry 

Ranch B Solar Plant 5 Silverado Power LLC PV California SCE

China Lake 14 PV California Naval Air Weapons 

Station

Concord Solar Farm 5 Shoe Show, 

Inc PV North Carolina Duke Energy Corporation

Desert Green Solar 

Farm 6.5 Soitec USA Inc CPV California SDG&E

Dos Rios Solar Project -

I 10 SunEdison LLC PV Texas CPS Energy

Dos Rios Solar Project -

II 10 SunEdison LLC PV Texas CPS Energy

East Lyme Solar Park 

Facility 5 GRE 214 East Lyme LLC PV Connecticut United Illuminating Company

Foresight Solar PV 

Project 5

Foresight 

Renewables, 

LLC

PV Arizona Tucson Electric Power 

Company

Grundman Solar Project 

(Bruceville Road) 18

Constellation 

Energy 

Group, Inc.

PV California Sacramento Municipal 

Utility District

Heber Solar PV Project 10

Ormat 

Technologies, 

Inc.

PV California Imperial Irrigation 

District

Holiday Solar Array 8.5 Clear Peak PV California SCE

 28 Denoting “PV” in the “Tech” column indicates that the panels to be selected will most likely (but not certainly) be 

c-Si.
45

Plant MW Developer or 

Owner

Solar 

Tech Location PPA With

Facility Energy, Inc

Hyder Solar Plant 16 PV Arizona Arizona Public Service 

Company

Kalaeloa Renewable 

Energy Park (Solar) 5.9 Multi-Owned PV Hawaii Hawaiian Electric Company, Inc.

Kalaeloa Solar II 5 SunPower 

Corporation PV Hawaii Hawaiian Electric Company, Inc.

Kauai Solar Plant 6

Alexander & 

Baldwin, 

Incorporated

PV Hawaii Kauai Island Utility 

Cooperative

Keystone Solar Project 6

Community 

Energy Solar 

LLC

PV Pennsylvania Exelon Generation 

Company, LLC

Lakeland Linder 

Regional Airport Solar 

Project

5.5 SunEdison 

LLC PV Florida City of Lakeland

Lancaster Dry Farm 

Ranch B Solar PV Plant 5 Silverado Power LLC PV California SCE

Lancaster WAD B Solar 

PV Plant 5 Silverado Power LLC PV California SCE

LanWest Solar Farm 6.5 Soitec USA 

Inc. CPV California SDG&E

Littlerock Solar Power 

Generation Station 5 Amonix, Inc. CPV California SCE

Lucerne Solar Power 

Generation Station 14 Amonix, Inc. CPV California SCE

Luke Air Force Base 

Solar Project 15 PV Arizona Arizona Public Service Company

McDowell Technical 

Community College 

Solar Plant

5

McDowell 

Green Energy 

LLC

PV North Carolina Duke Energy 

Corporation

Middlesex Apple 

Orchard Complex 6.7 KDC Solar LLC PV New Jersey County of Middlesex

Mitchell County Solar 

Project (Solar DD) 14

Solar Design 

& 

Development 

LLC

PV Georgia Georgia Power 

Company

Mohave County Solar 

Project 10 SOLON Corporation PV Arizona UniSource Energy Services, Inc.

Mount St. Mary's PV 

Park 16

Constellation 

Energy 

Group, Inc.

CdTe Maryland State of Maryland

Murfreesboro Solar 

Project 6.5 Duke Energy 

Renewables PV North Carolina

North Carolina Electric 

Membership 

Corporation
46

Plant MW Developer or 

Owner

Solar 

Tech Location PPA With

Napoleon Solar I Project 10

BNB 

Napoleon 

Solar LLC

PV Ohio Campbell Soup 

Company

NJ Oak Solar Farm 10 PV New Jersey Atlantic City Electric

Orion Solar Project 12

Fotowatio 

Renewable 

Ventures Inc.

PV California PG&E

Palm Springs Solar PV 

Project-II 5 Multi-Owned PV California SCE

PLP Kauai 1 Solar 

Thermal 10 Pacific Light & Power PV Hawaii Kauai Island Utility Cooperative

Prescott Solar Facility 10 SunEdison 

LLC PV Arizona Arizona Public Service Company

Queen Creek Solar Plant 19 PSEG Solar 

Source LLC PV Arizona Salt River Project

RE Columbia 3 Solar 

Facility 10 Recurrent Energy Inc. PV California SCE

REDCO Solar 1 5

Renewable 

Energy 

Development 

Corp.

PV California City of Needles

Rinehart Solar Farm 

Project - Stage I 10 BlueChip Energy, LLC PV Florida Florida Power Corporation

Rio Grande Solar Plant 5 Recurrent 

Energy Inc. PV California SCE

Ronkonkoma LIRR 

Station 5.5 enXco, Inc. PV New York Long Island Power Authority

Sierra View Solar IV 

Plant 19 Juwi Solar Inc. PV California SCE

Sierra View Solar V 

Plant 19 Juwi Solar Inc. PV California SCE

Somers Solar Center 

Facility 5 HelioSage Energy, LLC PV Connecticut United Illuminating Company

Somerset Solar Project 10 SunEdison 

LLC PV Texas CPS Energy

South Robeson Solar 

Farm 5 Strata Solar LLC PV North Carolina Carolina Power & Light Company

South Swan Solar PV 

Project 12 Amonix, Inc CPV Arizona Tucson Electric Power Company

SunEdison NM Solar 4 10 SunEdison 

LLC PV New Mexico Southwestern Public Service Company

SunEdison NM Solar 5 10 SunEdison 

LLC PV New Mexico Southwestern Public Service Company

Tropico Solar PV Plant 14 Foresight 

Renewables, PV California SCE
47

Plant MW Developer or 

Owner

Solar 

Tech Location PPA With

LLC

UA Tech CTC Solar PV 

Project 5 CTC Solar PV Arizona Tucson Electric Power Company

Victor Dry Farm Ranch A 

Solar PV Plant 5 Silverado Power LLC PV California SCE

Victor Dry Farm Ranch B 

Solar Plant 5 Silverado Power LLC PV California SCE

Vineland Solar One 

Expansion 12 PV New Jersey Vineland Municipal Electric Utility

West Tennessee Solar 

Farm 5 University of Tennessee PV Tennessee Tennessee Valley Authority

Westford Solar Project 4.5 Multi-Owned PV Massachusetts National Grid USA

Wharton Generating 

Station 10 PV Texas City of Houston

Westlands Solar Farms 

PV1 18

Westland 

Solar Farms, 

LLC

PV California PG&E

Total 589.2
48

Table B-2. Mid-Sized PV Projects Currently in Development (20–50 MW)

Project MW Developer or Owner Solar 

Tech Location PPA With

Adobe Solar 

Project 20 Fotowatio Renewable Ventures Inc. PV California SCE

Alamosa Solar 

Generating 

Project

30 Cogentrix Energy, LLC CPV Colorado Xcel

Alpaugh North 

Solar Plant 20 Solar Project Solutions, LLC PV California PG&E

Antelope Solar 

Farm (Mojave 

Solar 4)

20 Fotowatio Renewable 

Ventures Inc. PV California SCE

Antelope Solar 

Project - Tuusso 20 Multi-Owned PV California SCE

Apex Solar 

Power Project 20 Fotowatio Renewable Ventures Inc. PV Nevada NV Energy

Atwell Island 

Solar Plant 20 Solar Project Solutions, LLC PV California PG&E

Avra Valley 

Solar Project 25 NRG Energy, Inc. PV Arizona TEP

Borrego Springs 

Project 26 NRG Solar LLC PV California SDG&E

Central Antelope 

Dry Ranch C 

Solar Plant

20 Silverado Power LLC PV California SCE

Chicago 

Rockford Solar 

Project

20 Multi-Owned PV Illinois Ameren Illinois 

Company

Corcoran Solar 

Plant 20 Solar Project Solutions, LLC PV California PG&E

Cygnus Solar 

Project 25 Fotowatio Renewable Ventures Inc. PV California SCE

Del Sur Solar 

Power Plant 38 Beautiful Earth Group, LLC PV California SCE

First Solar/PNM 

PPA 22 First Solar CdTe New Mexico PNM

Florida Solar 1 25 PV Florida Tampa Electric

Holly Hill Grove 

1 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

2 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

3 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

4 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

5 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

6 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

7 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

8 20 National Solar Power, LLC PV Florida FPL
49

Holly Hill Grove 

9 20 National Solar Power, LLC PV Florida FPL

Holly Hill Grove 

10 20 National Solar Power, LLC PV Florida FPL

Illinois Solar 20 CdTe Illinois ComEd

La Salle Solar 

Farm 

(Invenergy)

20 Invenergy LLC CdTe Illinois Commonwealth Edison 

Company

LanEast Solar 

Farm 22 Soitec USA Inc CPV California SDG&E

LSR Kramer 

South Solar 20 LSR Kramer South, LLC PV California SCE

Marana Solar 

PV Project 35 Avalon Solar LLC PV Arizona TEP

Maryland Solar 

Project 20 Maryland Solar LLC PV Maryland FirstEnergy Solutions Corporation

McHenry Solar 

Farm 25 SunPower Corporation PV California Modesto Irrigation District

Mililani Solar 

Park Project 20 Castle & Cooke Incorporation PV Hawaii Hawaiian Electric Company, Inc.

Mojave Solar 

Project - Mojave 20 Fotowatio Renewable Ventures Inc. PV California SCE

Mountain View 

Solar Plant 20 NextEra Energy Resources LLC PV Nevada NV Energy

Murphy Flats 

Solar Project 20 Interconnect Solar Development, LLC PV Idaho Idaho Power Co.

Nevada Solar 

Project 20 Fotowatio Renewable Ventures Inc. PV Nevada NV Energy

Nicolis Solar PV 

Plant 20 Foresight Renewables, LLC PV California SCE

Niland Solar 

Project 23 SunPeak Solar, LLC PV California Imperial Irrigation District

North Edwards 

Solar 20 North Edwards Solar, LLC PV California SCE

North Lancaster 

Ranch Solar PV 

Plant

20 Silverado Power LLC PV California SCE

RE Columbia 2 

Solar Facility 20 Recurrent Energy Inc. PV California SCE

RE Rosamond 

Solar Plant 20 Recurrent Energy Inc. PV California SCE

San Luis Valley 

Solar Ranch 

Project

30 Iberdrola Renewables, 

Inc. PV Colorado Xcel

Searchlight 

Solar I 20 American Capital Energy, Inc PV Nevada NV Energy

Sierra Solar 

Greenworks 

Solar PV Plant

20 Silverado Power LLC PV California SCE

Simon Solar 

Farm (Social 

Circle)

30 Private Investor- Steve 

Ivey PV Georgia Georgia Power 

Company

Sorrento Eagle 

Dunes 40 BlueChip PV Florida Progress Energy, Inc.

Spectrum Solar 38 Fotowatio Renewable PV Nevada NV Energy
50

Power Plant Ventures Inc.

TA High Desert 

Solar Plant 20 Multi-Owned PV California SCE

Tierra Del Sol 

Solar Farm 45 Soitec USA Inc CPV California SDG&E

Turning Point 

Solar 49.9 Agile Energy PV Ohio Columbus Southern Power Co.

Victor Phelan 

Solar One Plant 20 Recurrent Energy Inc. PV California SCE

Victorville 

Landfill Solar 

Project

21 Axio Power Inc. PV California SCE

Weldon Solar 20 PV California SCE

White River 

Solar Plant 20 Solar Project Solutions, LLC PV California PG&E

Total 1,329.9
51

Table B-3. Large-Sized PV Projects Currently in Development (> 50 MW)

Project MW Developer or Owner Solar 

Tech Location PPA With

Agua Caliente 290 First Solar CdTe California PG&E

Alhambra Solar 

Project 50 SolarGen2 PV California SDG&E

Alpaugh Solar 50 Solar Project 

Solutions, LLC PV California PG&E

Alpine Solar 66 Alpine SunTower LLC PV California PG&E

Amargosa Farm Road 

Solar Power Project 500 Multi-Owned PV Nevada NV Energy

Amargosa North Solar 

Plant 150 Pacific Solar Investments Inc. PV Nevada NV Energy

Antelope Valley Solar 

Ranch One 230 First Solar, Inc. CdTe California PG&E

Arlington Valley Solar 

Energy Project II 125 LS Power Group PV California SDG&E

AVSP I Solar Project 325 SunPower 

Corporation PV California SCE

AVSP II Solar Project 276 SunPower 

Corporation PV California SCE

California Valley Solar 

Ranch 250 NRG PV California SCE

Catalina Solar Project 110 enXco Inc. PV California SDG&E

Centinela Solar 

Project 130 LS Power Group PV California SDG&E

Copper Mountain 

Solar II 150 Sempra Generation CdTe California PG&E

Desert Sunlight

Project 550 First Solar Inc. CdTe California PG&E

Estancia Solar Farm 50 Silverado Power PV New Mexico PNM

FRV Regulus Solar 

Project 75 Fotowatio Renewable Ventures PV California SCE

Gadsden Solar Farm 400 National Solar Power PV Florida Progress 

Energy, Inc.

Hardee Solar Farm 200 National Solar Power PV Florida Progress 

Energy, Inc.

Imperial Solar Energy 

Center South 130 Tenaska Solar Ventures CdTe California SDG&E

Imperial Solar Energy 

Center West 250 Tenaska Solar Ventures CPV California SDG&E

Mayflower Solar 

Project (SolarGen) 50 SolarGen2 PV California SDG&E
52

Project MW Developer or Owner Solar 

Tech Location PPA With

McCoy Solar Energy 

Project 750 NextEra Energy Resources LLC PV California SCE

Mesquite Solar I 170 Sempra Generation PV Arizona PG&E

Mount Signal Solar 

Project 50 US Solar Holdings PV California SDG&E

National Solar Power 

Project 400 National Solar Power, LLC PV Florida FPL

North Star Solar I 

Project 60 Multi-Owned PV California PG&E

Pearl Harbor Solar 

Project 300 Sempra Generation PV Hawaii

Hawaiian 

Electric 

Industries, Inc.

Quinto Solar Project 110 SunPower 

Corporation PV California SCE

Rugged Solar Farm 80 Soitec USA Inc CPV California SDG&E

Sacramento/Recurrent 

PPA 88 Recurrent Energy, Inc. PV California

Sacramento 

Municipal 

Utility District

Silver State North 140 NextLight Renewable 

Power, LLC CdTe Nevada NV Energy

Silver State South 250 NextLight Renewable 

Power, LLC CdTe California SCE

Solar Millennium 

Blythe Power Project 

(Photovoltaic)

1,000 Multi-Owned PV California SCE

Solar Millennium 

Palen Power Project 

(CA Solar 10)

500 Multi-Owned PV California SCE

Sonora Solar Project 

(SolarGen) 50 SolarGen2 PV California SDG&E

Sorrento Solar Farm 120 BlueChip Energy, LLC PV Florida FPL

Stateline Solar Project 300 First Solar, Inc. CdTe California SCE

Topaz Solar Farm 550 MidAmerican Energy CdTe California PG&E

Wonder Valley Solar 

Farm 100 Sustainable Energy Capital Partners PV California SCE

Total 9,425
53

Appendix C: Utility-Scale Solar and Power Purchase Agreements

Electric utilities, including investor-owned, municipal, and public, provide nearly all the 

electricity consumed by homes, businesses, and industries in the United States. Accordingly,

their adoption of renewable energy systems is critical to the success of the technologies. In 

response to RPS requirements and customer demand for more renewable energy, electric utilities 

throughout the country have signed long-term contracts for the output of large-scale renewable 

energy generating facilities in recent years. These long-term contracts, known as power purchase 

agreements (PPAs), guarantee a steady and predictable revenue stream from the project, which 

lowers its risk profile and facilitates investment.

Due to stringent RPSs and other initiatives, California’s three IOUs— PG&E, SCE, and SDG&E 

—lead in contracting with or developing solar projects. Figure 1 illustrates the significant gap 

between these utilities (particularly PG&E and SCE) in contracted solar megawatts relative to 

the other leading IOUs.

Figure C-1. Leading utilities with utility-scale solar in development (under contract or planned)

0

1000

2000

3000

4000

5000

CSP

PV
54

Appendix D: The Solar Resource

The solar resource, or quantity of sunlight, of the United States is significant. Total annual U.S. 

energy demand could theoretically be met with PV systems covering less than 1% of the nation’s 

land area (Denholm and Margolis 2008). The southwest United States—comprising California, 

Arizona, Nevada, Utah, New Mexico, Colorado, and western Texas—has some of the best solar 

resources in the world. In fact, Arizona, California, Nevada, and New Mexico are estimated to 

have the solar resources to produce 4.1 million MW of electricity, almost four times the electricgenerating capacity of the entire United States (DOE 2003; EIA 2008). The CSP and PV solar 

resource for the United States are shown in Figure D-1. 

Figure D-1. Concentrating and PV solar resources in the United States

Source: NREL 2010c

Despite abundant solar resources, significant economic barriers to widespread adoption remain. 

In particular, it is challenging to serve regions with modest solar resources, including arranging 

and underwriting the capital, building and maintaining the necessary transmission pathways, and 

assigning cost recovery through long-term contracts with utilities.

Furthermore, even in areas of high insolation (the measure of solar radiation striking a given area 

at a given time), finding suitable sites for large-scale solar installations can be difficult.

Figure D-2 compares the availability of solar resource in the southern California and Nevada

region—one of the best solar resource locations nationally—before and after considering various 

development factors. The left image depicts the regional resource with no “filters” or limitations 

to access. The right image depicts the same resource but with the following set of access 

limitations:

• Only premium solar resource (6.75 kWh/m2

/day and greater) 

• No use of environmentally-sensitive or restricted land (e.g., excludes land controlled 

by the U.S. Department of Defense)

• No use of land with grades of 1% or greater.
55

As readily seen in the side-by-side graphics, applying the access filters greatly reduces the 

potential resource. 

Figure D-2. Solar resource rear southern California without a filter (left) and with multiple filters 

applied (right)