Solar power in the United States includes utility-scale solar power plants as well as local distributed generation, mostly from rooftop photovoltaics. In mid-2013, the U.S. passed 10 GW of installed photovoltaic capacitywith an additional 0.5 GW of concentrated solar power. In the twelve months through October 2013, utility scale solar power generated 8.46 million megawatt-hours, 0.21% of total US electricity. The largest solar power installation in the world is the Solar Energy Generating Systems facility in California, which has a total capacity of 354 megawatts (MW).
The United States conducted much early research in photovoltaics and concentrated solar power. The U.S. is among the top countries in the world in electricity generated by the Sun and several of the world's largest utility-scale installations are located in the desert Southwest. There are plans to build many other large solar plants in the United States. While the U.S. has no national energy policy, many states have set individual renewable energy goals with solar power being included in various proportions. Governor Jerry Brown has signed legislation requiring California's utilities to obtain 33 percent of their electricity from renewable energy sources by the end of 2020. A total of 4,324 MW of utility scale solar power plants are under construction and an additional 25,926 MW are under development, with 19,060 MW under construction or development in California.
The use of solar water heating and solar area heating is less common in the U.S. than in some other countries.
A 1993 report by the United States Department of Energy found available domestic solar energy (including biomass) technically accessible regardless of cost amounted to 586,687 Quadrillion BTUs (Quads); 95% of this was biomass. Coal represented the second largest resource, a distant 38,147 Quads. Predictions of how much solar power was economically feasible to collect amounted to 352 quads, compared with 5,266 quads from coal. The assumptions used in the report were based on a predicted 2010 price of a barrel of oil being $38, and multiplied annual renewable resources by 30 for comparison with non-renewable resources. The total annual energy consumption of the United States in 2007 was approximately 100 Quads, less than 0.5% of what is theoretically available from sunlight.
A 2012 report from the National Renewable Energy Laboratory described technically available renewable energy resources for each state and estimated that urban utility scale photovoltaics could supply 2,232 TWh/year, rural utility scale PV 280,613 TWh/year, rooftop PV 818 TWh/year, and CSP 116,146 TWh/year, for a total of almost 400,000 TWh/year, 100 times current consumption of 3,856 TWh in 2011. Onshore wind potential is estimated at 32,784 TWh/year, and offshore wind at 16,976 TWh/year. The total available from all renewable resources is estimated at 481,963 TWh/year.
Solar energy deployment increased at a record pace in the United States and throughout the world in 2008, according to industry reports. The Solar Energy Industries Association's "2008 U.S. Solar Industry Year in Review" found that U.S. solar energy capacity increased by 17% in 2007, reaching the total equivalent of 8,775 megawatts (MW). The SEIA report tallies all types of solar energy, and in 2007 the United States installed 342 MW of solar photovoltaic (PV) electric power, 139 thermal megawatts (MWth) of solar water heating, 762 MWth of pool heating, and 21 MWth of solar space heating and cooling.
A report finds that solar power's contribution could grow to 10% of the nation's power needs by 2025. The report, prepared by research and publishing firm Clean Edge and the nonprofit Co-op America, projects nearly 2% of the nation's electricity coming from concentrating solar power systems, while solar photovoltaic systems will provide more than 8% of the nation's electricity. Those figures correlate to nearly 50,000 megawatts of solar photovoltaic systems and more than 6,600 megawatts of concentrating solar power.
As noted in the report, solar power has been expanding rapidly in the past eight years, growing at an average pace of 40% per year. The cost per kilowatt-hour of solar photovoltaic systems has also been dropping, while electricity generated from fossil fuels is becoming more expensive. As a result, the report projects that solar power will reach cost parity with conventional power sources in many U.S. markets by 2015. But to reach the 10% goal, solar photovoltaic companies will also need to streamline installations and make solar power a "plug-and-play" technology, that is, it must be simple and straightforward to buy the components of the system, connect them together, and connect the system to the power grid.
The report also places some of the responsibility with electric utilities, which will need to take advantage of the benefits of solar power, incorporate it into future "smart grid" technologies, and create new business models for building solar power capacity. The report also calls for establishing long-term extensions of today's investment and production tax credits, creating open standards for connecting solar power systems to the grid, and giving utilities the ability to include solar power in their rate base.
According to a study by the Solar Energy Industries Association and GTM Research, 878 megawatts (MW) of photovoltaic (PV) capacity and 78 MW of concentrating solar power (CSP) were installed in the U.S. in 2010, enough to power roughly 200,000 homes. In addition, more than 65,000 homes and businesses added solar water heating (SWH) or solar pool heating (SPH) systems. This was double the 435 MW installed in 2009 around the U.S.
According to a 2011 survey conducted by independent polling firm Kelton Research, nine out of 10 Americans support the use and development of solar technology. Eight out of 10 respondents indicated that "the federal government should support solar manufacturing in the U.S. and should give federal subsidies for solar energy". According to the Energy Information Administration, in 2010, subsidies to the solar power industry amounted to 8.2% ($968 million) of all federal subsidies for electricity generation.
Solar Energy Industries Association and GTM Research found that the amount of new solar electric capacity increased in 2012 by 76 percent from 2011, raising the United States’ market share of the world’s installations above 10 percent, up from roughly 5 to 7 percent in the last seven years.
History
One of the first applications of concentrated solar was the 6 hp solar powered motor made by H.E. Willsie and John Boyle in 1904.
An early solar pioneer of the 19th and 20th century, Frank Shuman, built a demonstration plant that used solar power to pump water using an array of mirrors in a trough to generate steam. Located in Philadelphia, the solar water pump station was capable of pumping 3000 gallons an hour (25 hp)at that latitude. After seven weeks of testing the plant was disassembled and shipped to Egypt for testing as an irrigation plant.
The U.S. pioneered solar tower and trough technologies. A number of different solar thermal technologies are in use in the U.S.
The largest and oldest solar power plant in the world is the 354 MW SEGS thermal power plant, in California. The 64 MW Nevada Solar One uses parabolic trough technology in one of the largest solar plants in the world.
The Martin Next Generation Solar Energy Center is a hybrid 75-megawatt (MW) parabolic trough solar energy plant that is owned by Florida Power & Light Company (FPL). The solar plant is a component of the 3,705 MW Martin County Power Plant, which is currently the single largest fossil fuel burning power plant in the United States. Completed at the end of 2010, it is located in western Martin County, Florida, just north of Indiantown.
The 5 MW Kimberlina Solar Thermal Energy Plant demonstrates a fresnel reflector technology. Sierra SunTower is a 5 MW commercial concentrating solar power tower in Lancaster, California and is the only CSP tower facility operating in North America. The 1.5 MW Maricopa Solar is the first Dish Stirling power plant. The 2 MW Holaniku MicroCSP Solar Thermal Plant in Hawaii is the world's first MicroCSP power plant.
In mid-2010, the U.S. produced more than half of all solar thermal power in the world, although Spain exceeded the U.S. in 2011.
As of June 24, 2013, a total of 1,187 MW of utility scale solar thermal power plants are under construction in the United States, with 938 MW expected to be operating by the end of 2013.
The Ivanpah Solar Power Facility is a 392 megawatt (MW) solar power facility, which is under construction. It will consist of three separate solar thermal power plants in southeastern California. The facility will consist of fields of heliostat mirrors focusing solar energy on boilers located on centralized power towers. The first phase of the Ivanpah facility began construction in late 2010.
The Solana Generating Station is a 280 MW solar power plant that is under construction near Gila Bend, Arizona, about 70 miles (110 km) southwest of Phoenix.
The Mojave Solar Project is a 280 MW solar thermal power facility under construction in the Mojave Desert in California, which should be completed in 2014. Abengoa has successfully secured a $1.2 billion loan guarantee from the US government for the project.
The Crescent Dunes Solar Energy Project is a 110 megawatt (MW) solar thermal power project currently under construction near Tonopah, about 190 miles (310 km) northwest of Las Vegas.
As of June 24, 2013, a total of 3,744 MW of solar thermal power plants are under development in the United States.
The Genesis Solar Energy Project is a proposed 250 MW solar thermal power station to be located in Riverside County, California. It will be of parabolic trough design, and the company involved is NextEra Energy Resources.