SunPower Corporation is an American energy company that designs and manufactures crystalline silicon photovoltaic cells, roof tiles and solar panels based on an all-back-contact solar cell invented at Stanford University. The company is owned 66% by Total, Europes third largest oil company, and is publicly traded on the NASDAQ as SPWR (formerly SPWRA and SPWRB); it is a component of the Dow Jones Oil and Gas Index DJUSEN. In 1997, the companys solar cells were used in NASA Pathfinder high altitude aircraft. In January 2007, SunPower corporation acquired PowerLight Corporation, a leading global provider of large-scale solar power systems In February 2010, it acquired Europes SunRay Renewable Energy for $277 million. On 29 April 2011, Total S.A. agreed to buy 60% of SunPower for US$1.38 billion. On 23 December 2011, the company announced an agreement to acquire Tenesol SA.