Agua Caliente Solar Project  |  Case Study

Flat Panel CdTe Thin Film Photovoltaic Solar Power Plant:  290 MW

  1. With completion of the 250 MW Phase 1 in September 2012, the Agua Caliente Solar Project thin film photovoltaic solar power plant surpassed Canada’s 80 MW Sarnia Photovoltaic Power Plant to become the largest operating solar PV power plant in North America.

  1. When completed in 2014, the Agua Caliente Solar Project will produce sufficient electricity to power about 100,000 homes per year, displacing approximately 220,000 metric tons of carbon dioxide (CO2) annually (the equivalent of taking about 40,000 cars off the road).  The 2,400 acre project is located on previously disturbed agricultural land and was selected after an extensive review of the available solar resource, proximity to existing electrical transmission lines, and current land uses.  Transmission access will be provided by the existing Hassayampa-North Gila 500 kv transmission line adjacent to the site.  The project owner, NRG Solar, estimates the photovoltaic generation facility will fund approximately 400 construction jobs and 10 full time operating jobs. 

  2. Developed by First Solar, the Topaz project incorporates the company's advanced thin- film cadmium telluride (CdTe) PV modules, which generate electricity with no emissions, waste or water use, and have the smallest carbon footprint of any PV technology.  The Agua Caliente project will occupy what is  essentially non-prime agricultural land that has limited productivity.  The project has been designed to minimize visual impact.  The panels installation will stand no more than 6 feet above ground and are constructed to withstand the region’s high winds.  Because of it’s location, the project will require minimal new transmission infrastructure.

  3. The Agua Caliente plant will eventually deploy 400 units of SMA's Sunny Central inverters. The project will deploy fault ride-through and dynamic voltage regulation, technologies that are new to solar power plants in the United States.

  4. Critical to the development of the Agua Caliente Solar Project is the Arizona Renewable Energy Standard.  In November 2006, the Arizona Corporation Commission (ACC) adopted final rules to expand the state's Renewable Energy Standard (RES) to 15% by 2025, with 30% of the renewable energy to be derived from distributed energy technologies (approximately 2,000 MW).  In June 2007, the state attorney general certified the rule as constitutional, allowing the new rules to go forward, and they took effect 60 days later.

  5. In February 2012, the Agua Caliente Solar Project competed in the Excellence in Renewable Energy Awards and won Project of the Year Award.

  6. Technology

  7. The CdTe (cadmium telluride) thin film photovoltaic cell that is at the heart of the First Solar process is the most widely used thin film solar panel technology.  Other photovoltaic materials commonly used in thin film solar cells include amorphous silicon (a-Si) and copper indium gallium selenide (CIS or CIGS).  Although not as efficient as crystalline silicon photovoltaic panels, thin film technology continues to be less costly (although dropping silicon costs have changed this dynamic dramatically in the past year) and more adaptable to building integrated photovoltaic (BIPV) installations.

  8. As of mid-2012, the ten most efficient monocrystalline silicon solar cells range from 19.1% to 22.5%. The top ten polycrystalline cell efficiencies range from 15.24% to 16.0%.  By way of comparison, in early 2012, commercial panel conversion rate efficiencies for thin film industry leader First Solar had reached 12.4%

  9. Project Development

  10. Project developer First Solar is one of the largest solar panel manufacturers and solar project developers in the world.  The company was formed in 1999.  Among First Solars achievements:  

  11. In the current extraordinarily competitive market they are still the cost leader at less than $0.75 per watt.

  12. The were the first solar PV company to produce 1 GW in a single year and have over 5 GW installed to date.

  13. Set world records for CdTe PV cell (17.3%) and PV module (14.4%) efficiency certified by NREL.

  14. Developed the first comprehensive, pre-funded module collection and recycling program in the PV industry.

  15. Attained the smallest carbon footprint and fastest energy payback time of any PV technology

  16. First Solar projects include over 5 GW installed and another 2.7 GW under construction or in development.  Among the noteworthy completed projects are the 80 MW Sarnia Solar Project, the 58 MW Copper Mountain Solar 1 facility, the 53 MW Lieberose Solar Park, and the 30 MW Cimarron Solar Facility.  Projects in development include the 550 MW Desert Sunlight Solar Farm. the 550 MW Topaz Solar Farm, the 290 MW Agua Caliente Solar Project, the 230 MW AV Solar Ranch One, and the 300 MW Stateline Solar Farm.

  17. Project owner, NRG Solar, LLC, is a subsidiary of NRG Energy, Inc., an multi-faceted energy company headquartered in New Jersey.  NRG's power plants provide more than 25,000 MW of generation capacity, enough to supply more than 20 million homes.   NRG’s generation fleet includes 29 conventional fossil-fuel power plants in 11 states.  Additionally, NRG has 6 operational clean energy facilities, including wind farms, a solar power plant, and the South Texas Nuclear Plant.  Beginning in 2009, NRG began a major initiative to become the leading green energy producer in the United States.  Their effort include onshore and offshore wind power plants, thermosolar and photovoltaic solar power plants, distributed solar power facilities, and re-powering of some of their traditional coal-fired plants with biomass.

  18. NRG Solar projects of note include the 290 MW Agua Caliente Solar Project, the 392 MW Ivanpah Solar Electric Generating Station, and the 250 MW California Valley Solar Ranch.

  19. Levelized Cost of Energy

  20. In 2012, the U.S. Energy Information Administration’s Annual Energy Outlook (AEO2012) estimated that the best case scenario levelized cost of energy (LCOE) for a generic new commercial-scale photovoltaic solar power plant would be $0.1222/kWh.  This best case estimate would be for an installation in a solar resource-rich location (southwest U.S.) and does not differentiate between silicon and thin film technologies.  This figure is inclusive of all direct costs and does not include any incentives or subsidies.  The AEO2012 LCOE figure represents a rather remarkable one year 23% ($0.0365/kWh) drop from the AEO2011 projections.

  21. For more information on LCOE and how photovoltaic solar power generation costs match up, see:  Levelized Cost of Energy:  Renewable energy has achieved parity.

  22. Financing

  23. In August 2011, the U.S. Department of Energy finalized a $967 million loan guarantee for the project.  The Department of Energy, through the Loan Programs Office, has issued loan guarantees or offered conditional commitments for loan guarantees totaling over $34 billion to support 33 clean energy projects.  The program's 10 generation projects will produce over 23 million MWh’s, enough to power over two million homes.  Loan Program supported clean energy generation projects include two of the world's largest concentrating solar power projects, multiple solar photovoltaic power plants, two geothermal projects, the world's largest wind farm, and the nation's first new nuclear power plant in three decades. 

  24. The project was initially developed by NextLight Renewable Power, LLC, a firm now owned by First Solar.  NRG Energy acquired the project in August 2011.  In early 2012, MidAmerican Renewables, LLC purchased a 49% share of the project.

  25. References

  26. greentech Media:  Largest Solar PV Plant in North America Comes On-Line


  28. First Solar:  Agua Caliente Solar Project


  30. Wikipedia:  Agua Caliente Solar Project


  32. Energy Resources:  Arizona solar project reaches 100 MW mark


  34. Solar Plaza:  Top 10 World’s Largest Solar PV Projects Under Construction


  36. Wikipedia:  List of Photovoltaic Power Stations


  38. SEIA (Solar Energy Industries Association):  Major Solar Projects Llst


  40. Solar Plaza:  World’s Largest Solar PV Project, Agua Caliente, Achieves 250 MW



  1. Yuma County, Arizona, United States

Project Status:

  1. Phase 1 completion:  2012

  2. Phase 2 completion:  2014 (projected)

Rated Capacity:

  1. Phase 1:  100 MW

  2. Phase 2:  190 MW

Annual Production:

  1. 626.219 GWh per year

Capacity Factor:

  1. 24.6% (solar resource:  2,405 kWh/m2/yr)

Carbon Offset:

  1. 220,000 metric tons CO2 per year


  1. NRG Energy, Inc. and MidAmerica Renewables, LLC


  1. First Solar, Inc.


  1. First Solar, Inc.

Generation Offtaker:

  1. Pacific Gas and Electric (PS&E).  25-year PPA

Generation Technology:

  1. Fixed-tilt, ground-mount First Solar CdTe thin film photovoltaic panels

Thermal Storage:

  1. N/A


  1. $1.8 billion