OAKLAND, Calif. — Recreational Equipment Inc. plans to add solar power installations at 11 of its stores this year.

The outdoor equipment co-op, which already purchases about 20 percent of its power from renewable sources, expects the photovoltaic solar installations to provide up to 35 percent of each store's energy. The project will eventually generate 1.1 million kilowatt hours of electricity.

REI consulted with Blue Oak Energy, a solar electric engineering firm, to decide which of the co-op's 103 stores should receive the solar treatment. Seven of the stores are in the California cities of Arcadia, Folsom, Sacramento, San Carlos, San Diego, San Francisco and Santa Rosa. Three are in Clackamas, Hillsboro and Tualatin, all in Oregon. The last will be REI's second prototype store, in Round Rock, Texas, built to test retail design and green building concepts.

The stores were chosen based on state incentives, utility rebates, cost of electricity and the size and condition of their roofs. REI will use the project to determine its future solar installation strategy.

Google, too, has expanded its support of solar energy. The company's philanthropic arm, Google.org, is providing funding to BrightSource Energy, a developer of large-scale solar thermal projects.

Google.org and BP Alternative Energy are among the investors providing $115 million funding to the Oakland, Calif., company. Earlier this year, Google.org announced it was giving $10 million in funding to eSolar, another solar thermal power company, as part of its Renewable Energy Cheaper Than Coal initiative.