Located in a desert area called the Valley of the Sun, the City of Phoenix “spends money like water”—very carefully. Now, metropolitan administrators have installed a 7.5-megawatt (MW) solar power array at Lake Pleasant Water Treatment Plant, northwest of Phoenix, which is expected to save the Arizona capital city and its 2.5 million residents about $4.2 million over the next 20 years, compared to conventional electricity.
The high-efficiency solar installation was designed and built by SunPower Corp. of San Jose, California. It represents the largest such installation ever on city property and is expected to generate 70 percent of the five-year-old water treatment plant’s electrical power needs.
At the site, a 6-MW ground-mounted solar array features a SunPower T0 Tracker system, which positions the 22,936 crystalline silicon photovoltaic 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. In addition, SunPower T10 Solar Roof Tile has been used for a 1.5-megawatt array atop a reservoir.
The solar system will save about 15 million kilowatt-hours (kWh) each year. 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."
The city also has a SunPower solar system that generates 5.4 MW at Phoenix Sky Harbor International Airport and 100 kW systems at the Phoenix Convention Center and Burton Barr Central Library, both with Leadership in Energy and Environmental Design (LEED) Silver-certified facilities.
"This is another great example of the progressive thinking that enables Phoenix to keep customer costs as low as possible," said Councilman Bill Gates (News - Alert), chairman of the city's Finance, Efficiency, Innovation and Sustainability Subcommittee. "City solar projects are currently generating 13 MW 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."
Phoenix is financing the system through a solar services agreement with SunPower. Under terms of the agreement, Wells Fargo (News - Alert) owns the system that SunPower designed, built, and will operate and maintain. The city will buy the electricity at rates that are competitive with retail electricity—minimizing the effect of rising electricity costs with no capital investment. The renewable energy certificates (RECs) associated with the system will be transferred to the utility, Arizona Public Service (APS), in fulfillment of the state's renewable energy standard. The project was facilitated in part by APS's Renewable Energy Incentive Program, which offers financial incentives to customers that help to offset up to 40 percent of the costs of installing solar energy.
This is not SunPower’s first time at the (water treatment) rodeo. The solar producer has completed four other such projects, totaling 3.8 MW at public water agencies and water treatment facilities in California.
Two of SunPower's systems are installed at the Rancho California Water District (RCWD) in Riverside County. One is a 1.1 MW system at Senga Doherty Pump Station, which offsets fully 95 percent of power costs ; the other, a 612-kilowatt (kW) solar parking canopy at the RCWD headquarters, offsets 55 percent. This totals the savings to approximately $4.3 million over the next 20 years.
The other two projects are a 1-MW installation at Castaic Lake Water Agency's Rio Vista Water Treatment Plant in Santa Clarita and a 983-kW system for the City of Galt's Wastewater Treatment plant. Both facilities use SunPower's T0 trackers.
Finally, in related news, on January 2, MidAmerican Energy Holdings, a subsidiary of Warren Buffet’s Berkshire Hathaway investment company, agreed to acquire and build two projects in California from Silicon Valley-based PV solar manufacturer SunPower Corporation. The Antelope Valley Solar Projects— two co-located projects in Kern and Los Angeles Counties — will generate a cumulative 579 megawatts (MW) of grid-tied energy, which will be sold directly to Southern California Edison (News - Alert) (SCE) under long-term power purchase contracts approved by the California Public Utilities . Together, the projects—worth between $ billion and $2.5 billion—will constitute the largest permitted solar photovoltaic power development in the world and will create an estimated 650 jobs during construction.
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Edited by Brooke Neuman