Just south of Las Vegas sits Nevada Solar One — a 64-megawatt solar thermal plant, the world's third-biggest solar energy field. The Boulder City facility is the first large-scale solar project of its kind — a parabolic trough power plant — to be built in the U.S. in more than 15 years. It's expected to generate 129 million kilowatt hours of solar electricity each year, enough to power 15,000 households. Project developer Acciona Solar Power, of Spain, selected Parker Hannifin Corp. to develop the motion control system for the solar panels. Hydraulic actuators designed and built by Parker rotate and tilt the solar collector assemblies, curved mirror surfaces, as they track the sun's motion like a field of futuristic sunflowers.