LAS VEGAS, NV - FEBRUARY 16: An airman shoots video of a panel washing robot cleaning a row of solar panels during a dedication ceremony to commemorate the completion of the 102-acre, 15-megawatt Solar Array II Generating Station at Nellis Air Force Base on February 16, 2016 in Las Vegas, Nevada. When coupled with the 13.2-megawatt Nellis Solar Star project completed in 2007, Nellis has the largest solar photovoltaic system in the Department of Defense. During daylight hours the two solar fields combined provide almost all of the base's energy needs or about 42 percent of its overall electricity requirements. Power from the array that is not used will go to the NV Energy grid and back into the local community. (Photo by Ethan Miller/Getty Images)
