SolarCity Corporation was a publicly traded company headquartered in Fremont, California that sold and installed solar energy generation systems as well as other related products and services to residential, commercial, and industrial customers. The company was founded on July 4, 2006, by Peter and Lyndon Rive, the cousins of SpaceX and Tesla CEO Elon Musk. Tesla acquired SolarCity in 2016, at a cost of approximately US billion in ) and reorganized its solar business into Tesla Energy. SolarCity heavily focused on door-to-door sales of leased systems, where customers would pay no upfront costs, but agreed to purchase the power generated by those panels from the company for 20 years. The business model became the most popular in the US and made the company the largest residential solar installer, but it caused SolarCity to have over billion in ). Prior to its acquisition by Tesla, the two companies had a co-marketing relationship, announced in the 2006 first Tesla master plan. Tesla CEO Elon Musk served as the chairman of SolarCity, SolarCity offered free charging to Tesla Roadster owners at its charging stations, and SolarCity became one of the first installers of the Tesla Powerwall home energy storage battery. SolarCity was founded in 2006 by brothers Peter and Lyndon Rive, based on a suggestion for a solar company concept by their cousin, Elon Musk, who was the chairman and helped start the company. By 2009, solar panels it had installed were capable of generating 440 megawatts (MW) of power. In 2011, the company launched their expansion to the East Coast with the acquisition of the solar division of Clean Currents and groSolar. Following the acquisitions, SolarCity expanded operations on the East Coast and opened in Connecticut, Pennsylvania, South Carolina, Florida, Vermont, and New Hampshire. In 2013, SolarCity was the leading residential solar installer in the U.S.