U.S. leaders in the sales and installation of roof-top solar panels, SunPower and SolarCity, have not been immune from the downturn in the industry. In early May SunPower reported its sixth consecutive period of quarterly losses and laid off 25 percent of its workers. Tesla-backed SolarCity, accounting for 41 percent of the solar installation market, reported a 39 percent decline in installations year over year for the first quarter.