Today Wal-Mart Stores, Inc. (NYSE: WMT), announced a major purchase of solar power from three solar power providers, BP Solar, SunEdison LLC, and PowerLight, a subsidiary of SunPower Corporation, for 22 combined Wal-Mart stores, Sam's Clubs and a distribution center in Hawaii and California. As part of a pilot project to determine solar power viability for Wal-Mart, the total solar power production...