The Southern California division of Edison International said Tuesday that it has agreed to buy 245 megawatts of thermal-solar power from plants to be built by Pasadena-based hi-tech business incubator Idealab.

The Antelope Valley plants will be built by eSolar and will begin operating in 2011, Edison said Tuesday in a release.

The project creates steam made by solar heat generated by an array of mirrors covering 160 acres, according to eSolar’s Web site.

Since one megawatt can power up to 1,000 average homes, the project will create enough power to supply up to 245,000 homes.

The project is a move by the state’s largest utility provider to meet increasing demand for power and also to increase the supply of power from renewable sources by 1 percent annually until reaching 20 percent in 2020, in accordance with state laws.

The Rosemead-based utility has gotten more interested in renewable power. Edison said recently it plans to install $875 million worth of rooftop solar panels in Los Angeles County in order to meet peak demand, and it inked a deal for 250 megawatts of energy from a big wind farm in the Tehachapi Mountains.

Shares in Edison were down 8 cents to $52.29 in early trading Tuesday.

ESolar recently raised $130 million in venture funding from Google’s nonprofit arm, Google.org, and Oak Investment Partners to help fund the development of its utility-scale solar projects.