The world’s largest solar power plant cleared an important hurdle on Wednesday, laying the groundwork for a dramatic expansion in solar energy generation in the United States and around the world. The proposed $6 billion-plus Blythe, California plant, originally proposed by Chevron Corp. and Solar Millennium AG, won clearance to build from the California Energy Commission. The plant has a capacity of 1,000 megawatts. By comparison, for all of last year, the U.S. installed about 481 megawatts of solar energy, according to the Solar Energy Industry Association. The largest solar plants to date are in the 200-350 megawatt range.