The Desert Sunlight Solar Farm, located in Riverside County about 270km east of downtown Los Angeles, was operating at full capacity and providing 550 megawatts of electricity to the grid, the Department of the Interior said.
The farm's official opening on Monday (local time) came weeks after California Governor Jerry Brown laid out an ambitious plan for 50 percent of the state's electricity to be generated by renewable resources over the next 15 years.
At its unveiling, Secretary of the Interior Sally Jewell commended Brown for "implementing policies that take action on climate change and help move our nation toward a renewable energy future."
The farm provides enough energy to power 160,000 average homes and displaces 300,000 tons of carbon dioxide per year - the equivalent of taking 60,000 cars off the road, the agency said.
The farm is located on about 4,000 acres (1,619 hectares) managed by the federal Bureau of Land Management, the sixth solar project opened on public lands since 2009, Jewell said.
The power generated is being provided to Pacific Gas & Electric Company and Southern California Edison under long-term contracts, said the farm's developer, Arizona-based First Solar.
Project owners, NextEra Energy Resources, LLC, GE Energy Financial Services, and Sumitomo Corporation of Americas, benefited from about $1.5 billion in federal loan guarantees from the Department of Energy.
The loan program has been derided as a waste of money, with critics pointing to several large startups that took federal money then declared bankruptcy.
But in November, a Department of Energy report showed the program was in the black, with interest payments from funded projects bringing in more money than the losses sustained from failed loans.
The Desert Sunlight Solar Farm was built using photovoltaic technology, which has become less expensive in recent years as scientists develop panels from materials that absorb most of solar spectrum and work in various atmospheric conditions, rather than only in direct sunlight.
To minimize environmental impact, the Bureau of Land Management was finding "suitable habitat" for desert tortoise and other wildlife impacted by the farm's construction, federal officials said.
