Southern California Edison on Tuesday announced an agreement with First Solar Inc. to build two photovoltaic solar power projects in the Inland Empire, each with a capacity of 550 megawatts.

The utility, owned by Rosemead’s Edison International, said the projects would be in Riverside and San Bernardino counties and provide enough power to supply 170,000 homes when completed in 2015.

First Solar, based in Tempe, Ariz., is the one of the world’s largest producers of photovoltaic cells, which convert sunlight into electricity. The company will design and build the projects.

Pending state regulatory approval, construction will begin in 2012 on the Desert Sunlight project, near the Riverside County town of Desert Center. Construction on the Stateline facility in northeastern San Bernardino will begin in 2013. Financial terms of the deal were not announced.

Southern California Edison delivered about 65 percent of solar energy produced in the United States last year. Utilities have come under increasing pressure to provide more of their electricity from renewable sources, but the pace of new projects slowed last year when the credit crunch made it more difficult to obtain financing.

“Southern California Edison is always looking for innovative ways to deliver clean power from renewable sources,” Stuart Hemphill, senior vice president for power procurement, said in a statement. “This agreement is good for our customers, for the industry and for the environment.”

Edison International shares were down 12 cents, or less than 1 percent, to $31.56 in midday trading on the New York Stock Exchange.