MidAmerican's giant California Solar Star power plant enters service

(Reuters) - Renewable power companies MidAmerican Solar and SunPower Corp said they have connected the first 57 megawatts to the power grid from California's 579-MW Solar Star solar power plant, one of the biggest in the United States.

Their Solar Star project, which involves two plants in Kern and Los Angeles counties, are expected to power about 255,000 homes once complete, the two companies said in a release late on Thursday.

"We are fulfilling our promise ... to help California meet its mandate to generate 33 percent of its power from renewable sources by 2020," Mike Fehr, MidAmerican Solar's general manager at the Solar Star projects, said in the statement.

MidAmerican Solar is a unit of Berkshire Hathaway Inc's MidAmerican Energy Holdings energy subsidiary. MidAmerican Solar owns the Solar Star projects, which were designed and built by U.S. solar power company SunPower.

The two companies said construction began in early 2013 and was expected to be finished by the end of 2015. The projects currently employ approximately 600 workers at the sites.

Southern California Edison, a unit of California power company Edison International, will purchase electricity from the projects under two long-term power purchase contracts.

When complete, the companies said the Solar Star projects are expected to have more than 1.7 million panels installed, covering 3,230 acres.

(Reporting by Scott DiSavino; Editing by Sophie Hares)