SAN JOSE, Calif. — T. J. Rodgers is surrounded by a sea of silicon wafers on the roof of his company's headquarters in a Silicon Valley industrial park. No, not the ones that Mr. Rodgers, who founded Cypress Semiconductor in 1982, used to make high-speed computer memories or the newer specialized chips that go into iPods and high-end Mercedes-Benzes. These wafers are soaking up the sun's rays and turning them into electricity. On the roof, he fusses over the occasional weed that has grown up in the cracks between the panels and speculates about using robots to keep the glass...