The Agua Caliente Solar Photovoltaic (PV) facility in southern Arizona, currently the world’s largest solar PV plant, completed construction on April 29.

The 290-MW project—located between Phoenix and Yuma—is jointly owned by NRG Energy, through its subsidiary NRG Solar, and MidAmerican Solar, a subsidiary of MidAmerican Renewables. The plant will sell its electricity to Pacific Gas & Electric under a 25-year power purchase agreement.

The development of Agua Caliente was supported by a $967 million loan guarantee from the U.S. Department of Energy.  First Solar Inc. designed and constructed the plant using its thin-film solar PV technology, and will operate it for NRG and MidAmerican.

Agua Caliente is one of a series of large solar projects built to support California’s 33% by 2020 renewable portfolio standard (RPS). Others include the 392-MW Ivanpah concentrating solar plant near Las Vegas, which came online in February, NRG’s 250-MW California Valley Solar Ranch near San Luis Obispo, which was completed in 2013, and Exelon’s 230-MW Antelope Valley Solar Ranch northeast of Los Angeles.

“Large-scale utility accomplishments, like our Agua Caliente project, raise the bar in terms of our clean-energy technology and production,” said Tom Doyle, president, NRG Solar. “Proving that we can build both the world’s largest solar thermal and now one of the world’s largest solar photovoltaic facilities advance NRG’s mission to reshape the energy landscape that is incredibly beneficial to both the economy and in how we produce and consume energy.”

The Agua Caliente plant will not hold its title for long, however, as another MidAmerican and First Solar project, the Topaz Solar Farm near San Luis Obispo, is nearing completion and will total 550 MW when it comes online later this year.

Topaz and Agua Caliente may also be the last of such projects in the U.S. for a while, as demand for large solar PV plants has slowed now that California’s utilities say they have enough capacity in development to meet the RPS.

—Thomas W. Overton, JD is a POWER associate editor (@thomas_overton, @POWERmagazine)