Tracking Solar Powers South San Joaquin Irrigation District

The solar energy experts at Denver-based Conergy Americas and officials at California’s South San Joaquin Irrigation District (SSJID) have installed a single-axis solar tracking system featuring thin-film photovoltaic cells.

The 419-kilowatt system went live in late March. It is the second phase of a 1.6 MW solar energy solution that will save the irrigation district nearly $400,000 a year in utility costs and stabilize customer costs in the midst of a state-wide water crisis.

The project – known as the Robert O. Schulz Solar Farm -- will provide a unique cost-benefit analysis on how two distinct solar energy solutions – crystalline panels and thin-film – perform under a range of climatic conditions.

SSJID is located in Manteca, between San Francisco and Yosemite National Park. The district provides irrigation water for 55,000 acres in the surrounding area. The Solar Farm will handle nearly all the power needs of the nearby Nick C. DeGroot Water Treatment Plant, which processes 40 million gallons of water per day for 155,000 residents and businesses in the cities of Manteca, Tracy, Escalon, and Lathrop.

“The application of thin-film on a solar tracking system as a way to optimize energy output in perennially dusty or overcast areas is generating a great deal of excitement not only among those in areas with conditions similar to California’s Central Valley, but among economic policymakers and environmental stewards in Washington, D.C.,” said SSJID General Manager Jeff Shields. “We’re eager to continue our work with Conergy to bring this solution -- and the important data it’s generating in our cost-benefit analysis -- to light,” he added.

“The project’s main goal was to stabilize electrical costs, which can spike substantially in summer months given local time of use (TOU) metering;” said SSJID Utility Systems Director Don Battles.

SSJID is receiving $6 million in cash incentives from the California Solar Initiative program, designed to stimulate solar markets by providing cash incentives of up to 30 percent of system costs for businesses, public agencies, and homeowners who go solar.

Phase 1 features 6,720 Conergy 175-watt crystalline modules mounted on a single axis solar tracking system. Tracking systems can optimize peak-time output by as much as 15 percent over similarly-sized fixed-mount systems. This project optimizes its solar tracking capabilities using software whose origins are based in military tracking technologies. It took four months to install.

Thin-film modules were selected for the Phase 2 tracking solution because they perform at a lower cost-per-watt than traditional crystalline. Early indications show the output per DC kW of First Solar thin-film is about 10 percent higher than that of crystalline, according to the release. Installation time was three months.

Conergy designs, manufactures, installs, and finances solar photovoltaic solutions for major commercial sectors, public agencies, businesses, and homeowners.

In 1909, SSJID was established to provide a reliable and economical source of irrigation water for approximately 72,000 acres of agriculture in, and surrounding, Escalon, Ripon and Manteca. The district's historic water rights allow for several hydroelectric power plants on a series of dams and reservoirs on the Stanislaus River. SSJID and Oakdale Irrigation District completed the original Melones Reservoir in 1926 and have co-owned the Tri-Dam Project, consisting of Donnells, Beardsley, and Tulloch reservoirs and powerhouses, since 1957. In 2005, the district expanded into providing domestic water service to Tracy, Lathrop, Manteca, and other parts of San Joaquin County with its state-of-the-art membrane filtration water treatment plant.