The cities of Fairfield and Vacaville, Calif., have announced the completion of a 1.1-megawatt solar system designed, procured and constructed by SolarWorld, the U.S. solar manufacturer for more than 35 years, and owned and operated by Sustainable Power Group (sPower), an independent power producer based in Salt Lake City. The array powers the North Bay Regional Water Treatment Plant, a facility the cities co-own on the Sacramento River delta.

Comprised of more than 4,000 of SolarWorld’s American-made solar panels, the system is expected to generate about 2 million kilowatt-hours of renewable energy a year, which will result in immediate savings to Fairfield and Vacaville by limiting utility demand charges that accrue during peak usage times. The solar array uses single-axis-tracker technology to rotate the solar panels to follow the sun’s path, capturing more solar energy and requiring a smaller footprint, compared with a fixed-tilt system.

“Fairfield’s goal is to utilize solar power to secure a clean alternative energy supply that will reduce the city’s overall energy costs and help keep operating costs down,” said Felix Riesenberg, Fairfield’s assistant director of Public Works. “This is yet another example of the Fairfield water utility being innovative to reduce operational costs and to minimize future rate increases.”

“Vacaville has a long history of embracing solar and alternative energy projects as a way to save money and protect the environment, and this one fits nicely with that approach,” said Steve Sawyer, Vacaville’s interim assistant director of Utilities.

The project resulted from a partnership among Fairfield, Vacaville, SolarWorld and sPower. Under terms of the partnership, SolarWorld’s engineering, procurement and construction (EPC) division, based in Camarillo, Calif., managed all phases of the installation, including design, engineering, procurement, permitting and construction. SPower owns the solar equipment and provides the project’s financing through a 20-year power purchase agreement (PPA) with Fairfield.

Under the sPower PPA, Fairfield and Vacaville will purchase energy at a lower rate than they pay to buy power from Pacific Gas & Electric Co., their local utility. Over the 20-year life of the PPA, the cities are expected to save an estimated $2 million.