SAN JOSE, Calif., Jan. 15, 2013 /PRNewswire/ -- The city of Phoenix's Lake Pleasant Water Treatment Plant has started working directly with the sun to help produce the energy needed to operate the plant, which produces 15 billion gallons of tap water each year. A 7.5-megawatt high efficiency solar power system, which was designed and built by SunPower Corp. (NASDAQ: SPWR) and is the largest such installation on city property, is expected to generate 70 percent of the plant's electrical power needs. A total of 22,936 solar panels are being used to save approximately 15 million kilowatt-hours (kWh) each year, resulting in savings of approximately $4.2 million over the next 20 years as compared to conventional electricity. (Photo: http://photos.prnewswire.com/prnh/20130115/SF43022) According to estimates provided by the U.S. Environmental Protection Agency, the system is expected to offset the production of more than 9,000 tons of carbon dioxide per year, which is equivalent to removing almost 35,800 cars from Arizona's roads over the next 20 years. "With more than 300 days of sunshine each year, Phoenix is a natural for using solar power," said Phoenix Mayor Greg Stanton. "The Lake Pleasant Water Treatment Plant project is the latest in a series of solar initiatives utilized at various city locations to increase the city's commitment to sustainable energy development." "This is another great example of the progressive thinking that enables Phoenix to keep customer costs as low as possible," said Councilman Bill Gates, chairman of the city's Finance, Efficiency, Innovation and Sustainability Subcommittee. "City solar projects are currently generating 13 megawatts of electricity through solar energy, or enough to power about 2,600 homes annually." "This SunPower solar system will reliably produce clean energy for years to come," said Howard Wenger, SunPower president, regions. "SunPower's technology will ensure that the system delivers energy over the long term, reducing operational expenses significantly with no upfront expenditure." According to the city of Phoenix, a SunPower solar system also generates 5.4-megawatts of power at Sky Harbor, and 100-kilowatt systems are in place at the Phoenix Convention Center and the Burton Barr Central Library, both with Leadership in Energy and Environmental Design (LEED) Silver certified facilities. At the Lake Pleasant Water Treatment Plant, a 6-megawatt ground-mounted solar array features a SunPower T0 Tracker® system, which positions solar panels to follow the sun's movement during the day, increasing sunlight capture by up to 25 percent over conventional fixed-tilt systems, while significantly reducing land use requirements. The SunPower T10 Solar Roof Tile was used for a 1.5-megawatt array atop a reservoir.