California's next source of renewable power could be an orbiting set of solar panels, high above the equator, that would beam electricity back to Earth via a receiving station in Fresno County. Pacific Gas and Electric Co. has agreed to buy power from a startup company that wants to tap the strong, unfiltered sunlight found in space to solve the growing demand for clean energy. Sometime before 2016, Solaren Corp. plans to launch the world's first orbiting solar farm. Unfurled in space, the panels would bask in near-constant sunshine and provide a steady flow of electricity day and night. Receivers...