NextEra Energy Resources and its partners have commissioned the Blythe and McCoy, the two solar energy centres in California, US.
NextEra Energy Resources has built and will own and operate the projects.
NextEra Energy Resources president and CEO Armando Pimentel said: "These projects represent a more than $1.2bn investment in California and a tremendous step forward to help the state meet its renewable energy goals.
"We are very pleased to bring these solar energy centers online to help serve the state and boost the local economy."
The Blythe and McCoy Solar Energy Centers feature more than 4 million solar panels with trackers that will follow the sun from east to west each day to maximize energy production.
Together, they have a generating capacity of 485 megawatts, capable of powering more than 181,000 homes. The energy will serve customers of Southern California Edison and help health care provider Kaiser Permanente become 'carbon net positive.'
The projects' solar arrays span more than 4,000 acres of land in Riverside County, much of it managed by the U.S. Bureau of Land Management (BLM).
BLM Director Neil Kornze said: "The completion of these projects is further proof that America's shift toward clean, renewable energy is underway.
"In fact, we've seen a threefold increase in wind and a fivefold increase in solar power generation during this Administration. That's a foundation for the future that we should all be proud of."
By using renewable energy from the sun, the projects will avoid approximately 774,000 tons per year of carbon dioxide emissions that would have been produced if the electricity had been generated using fossil fuels.
California Energy Commissioner Karen Douglas said: "California leads the nation in renewable energy and these projects demonstrate that commitment.
"They are great examples of renewable energy projects on public lands that are helping us address climate change while respecting the many important values of the desert environment."
The projects have created a significant economic boost for Riverside County and Southern California, creating 1,500 construction jobs since 2014, when the project began.
From labor and materials, to housing, health care and construction – a wide variety of local businesses have benefitted from the influx of economic activity.
Riverside County Supervisor John J. Benoit said: "California, and Riverside County in particular, is fortunate to have one of the best solar resources in the country.
"These projects are evidence of what we can do when we build strong partnerships to develop renewable energy, protect the environment and create good jobs and long-term benefits for our communities."