Solar power in California


has been growing rapidly in the U.S. state of California because of high insolation, community support, declining solar costs, and a renewable portfolio standard which requires that 60% of California's electricity come from renewable resources by 2030, with 100% by 2045. Much of this is expected to come from solar power via photovoltaic facilities or concentrated solar power facilities.
At the end of 2023, California had a total of 46,874 MW of solar capacity installed, enough to power 13.9 million homes in the state. California ranked as the highest solar power generating state in the nation, with solar power providing for 28% of the state's electricity generation. The Solar Energy Industries Association predicts that California will increase its solar capacity by over 20,000 MW over the next five years, the second highest increase in solar capacity in the country behind Texas at 41,000 MW.
The state government has created various programs to incentivize and subsidize solar installations, including an exemption from property tax, cash incentives, net metering, streamlined permitting for residential solar, and, in 2020, requiring all new homes have solar panels.

History

Over the last 20 years, California has been home to a number of the world's largest solar facilities, many of which are located in the Mojave Desert. In 1991, the 354 MW Solar Energy Generating Systems plant held the title until being bested by the 392 MW Ivanpah Solar Electric Generating System, a solar thermal plant located in San Bernardino County near the Nevada border.
The early to mid 2010s saw the sharpest increase in solar development. By the end of 2013, California had 490 MW of concentrated solar power and 5,183 MW of photovoltaics capacity in operation.
In 2014, the 550 MW Topaz Solar Farm became the new "world's largest operational" solar facility and went online in San Luis Obispo County, California. A second 550 MW facility, Desert Sunlight Solar Farm, went online in Riverside County in 2014, constructed by First Solar. In June 2015, the 579 MW Solar Star facility went online, becoming the new largest operational solar facility and making California host to the three largest photovoltaic solar facilities in the world. There are several proposals for even larger facilities seeking regulatory approval in California, such as the 2.7 GW Westlands Solar Park.
In 2014, California led the nation in the number of homes which have solar panels installed, totaling over 230,000. Many were installed because of the Million Solar Roof Initiative.
In December 2017, the Solar on Multifamily Affordable Housing program was approved by the California Public Utilities Commission. The program plans to allocate one billion dollars from the state's greenhouse gas cap-and-trade program to incentivize owners of affordable, multi-family buildings to install solar, with a goal of adding 300 MW of capacity by 2030.
In May 2018, the California Energy Commission required that nearly all new homes under four stories be built with rooftop photovoltaic solar panels. Developers can also receive approval from the CEC to subscribe new homes to local community solar generation. In early 2020, the Sacramento Municipal Utility District was approved to provide community solar to new homes in Sacramento.
Solar systems with battery storage are now much more valuable than systems without battery storage, mostly because new solar generation exacerbates the duck curve. Solar production causes fossil-fuel power plants to be turned down to minimum during the day, but when solar production stops in the evening peaker plants must quickly ramp generation by 5GW an hour to supply peak demand. New solar generation only displaces other solar generation and increases the supply ramping needed by peaker plants, which is expensive for utilities. Battery storage systems flatten the duck curve by storing solar and wind energy at non-peak hours and discharging it at peak hours. Battery output peaked at 10 GW in May 2025, of a 15.7 GW capacity. California's most recent [|net energy metering policy] now incentivizes systems with battery storage more than solar systems with no installed storage.
Housing affordability is also a concern with this measure, an area where California already struggles greatly. According to a 2017 survey conducted by the U.S. Census Bureau, 37.8% of California homeowners with mortgages are "cost-burdened," with housing costs exceeding 30% of the household income, and 16.3% face housing costs exceeding 50% of the household income. The CEC predicts that the requirement of photovoltaic panels will increase the cost of a newly built single-family home by about $40 per month in extra mortgage payments, but eventually save about $80 on electricity costs. The CEC released data showing that the system would more than pay for itself, however charitable organizations such as Habitat for Humanity have expressed their concerns as this will require the organization to receive additional donations to pay for the photovoltaic panels that the group would be required to install on every house it builds.

Photovoltaics

In 2011, California's goal to install 3,000 MW of distributed generation by 2016 was expanded to 12,000 MW by 2020.
California has more photovoltaics installed than any other federal state, and 48% of the U.S. total in 2010. For the first time in 2008 the installed photovoltaics exceeded the state's 354 MW of solar thermal. There are plans to build over 15,000 MW of utility scale photovoltaic plants in California. At the end of 2012, small systems of less than 10 kWp were averaging $5.39/W, and large systems of over 500 kWp were averaging $2.77/W.
California has the technical potential to install 128.9 GW of rooftop solar panels, which would generate 194,000 GWh/year, about 74% of the total electricity used in California in 2013. This is environmentally desirable because it would conserve large swaths of desert by placing panels atop preexisting structures instead. However, this would supply three to four times peak midday demand, requiring output to be stored or exported on sunny days.

Planned

California has several large concentrated solar power plants.
The Ivanpah Solar Electric Generating System, located southwest of Las Vegas and developed by BrightSource Energy and Bechtel, is the world's largest solar thermal power project.
The project has received a $1.375 billion loan guarantee from the United States Department of Energy.
It deploys 347,000 heliostat mirrors focusing solar energy on boilers located on centralized solar power towers.
The Genesis Solar Energy Project is an operational 250 MW solar thermal power station located in Riverside County, California. It features a parabolic trough design and is run by NextEra Energy Resources.

Operational

  • The Solar Energy Generating Systems, is a 361 MW parabolic trough concentrated solar power station located in the Mojave Desert completed in 1990.
  • The Genesis Solar Energy Project, is a 280 MW parabolic trough concentrated solar power station located in the Mojave Desert completed in 2013.
  • The Ivanpah Solar Power Facility, is a 392 MW solar power tower concentrated solar power station located in the Mojave Desert completed in 2014.
  • The Mojave Solar Project, is a 280 MW parabolic trough concentrated solar power station located in the Mojave Desert completed in 2014.
Total operational installed gross power is 1,313 MW. Production in 2015 was 2,309 GWh, 71.2% of U.S. total solar thermal generation.

Planned

, near Bakersfield, California, a solar EOR facility that is projected to eliminate 376,000 metric tons of carbon emissions. It was announced in November 2017 as a joint venture between GlassPoint Solar and Aera Energy.
In 2012, the Bureau of Land Management gave priority status to 5 solar project proposals in California. The 750 MW McCoy Solar Energy Project was proposed by NextEra, though only 1/3 of that wattage was ever installed. The remaining development of the project is currently on hold. The 100 MW Desert Harvest project has been proposed by enXco. The 664 MW Calico Solar Energy Project was redesigned by K Power but later abandoned.