State regulators have approved a Mojave Desert solar power contract for Southern California Edison.

The California Public Utilities Commission on Thursday approved a 20-year agreement for SCE, a subsidiary of Rosemead-based Edison International, to buy solar-generated power from a proposed plant owned by Solar Millennium in Blythe, near the Arizona border.

Solar Millennium LLC, a Berkeley subsidiary of a German company, is planning to build two solar generating facilities using arrays of solar collectors to generate electricity. The two facilities, which are set to begin operating in 2014, would generate 484 megawatts of energy, enough to supply the power needs for at least 250,000 homes for a year.

The Solar Millennium plant has been designated as a fast-track project by the federal Bureau of Land Management, making it eligible for federal economic stimulus funds.

Under state law, Southern California Edison and the state’s two other investor-owned utilities – Pacific Gas & Electric and San Diego Gas & Electric – are required to have 20 percent of their power portfolios come from renewable energy resources by the end of this year. Edison is the farthest along, with nearly 18 percent of its portfolio coming from renewables.