The 22.7-Percent Efficient X-Series Solar Panel Offers Unsurpassed Performance, Reliability and Aesthetics SAN JOSE, Calif.: SunPower (NASDAQ:SPWR), one of the world’s most innovative and sustainable energy companies, will formally introduce its highest efficiency X-Series residential solar panel this week during Intersolar Europe in Munich, Germany. At 370-watts and 22.7-percent efficiency, it is the most efficient […]