Environmental Protection

PPA Allows Oro Loma Sanitary District to Turn on Solar Savings

Solar Power Partners and Oro Loma partnered with DRI Energy to design, build, and install the single-axis tracker project that is expected to save the district $2 million over the life of the contract.

Oro Loma Sanitary District, Solar Power Partners, and DRI Energy jointly announced the completion of a single-tracker system, 468 kW-sized photovoltaic solar system, which is designed to save the district more than $2 million during the life of the contract. Oro Loma had no out-of-pocket costs because the district agreed to a solar Power Purchase Agreement (PPA) with MillValley-based Solar Power Partners, who developed, financed, and will own and operate the facility.

Solar Power Partners and Oro Loma partnered with DRI Energy to design, build, and install the single-axis tracker project. DRI Energy used over 2,100 Trina Solar 220-watt modules on a Raytracker single-axis tracking system. The system can generate more than 822,000 kWh annually, saving the equivalent of 590 metric tons of carbon dioxide, equal to the one-year greenhouse gas emissions of 113 passenger vehicles.

“When the output from the solar array is combined with Oro Loma’s existing digester gas facility, the district will become 100 percent self sufficient in its electrical needs. The project makes sense from an environmental and economic perspective. We get electricity derived from the sun at a discount to existing utility rates,” said Jason Warner, Oro Loma Sanitary District general manager.

In 2008, the district undertook the development of a solar project that would deliver power to its wastewater treatment facility but initial parties involved were unable to complete the terms of the agreement. Solar Power Partners, who developed, owns, and operates several other solar systems for water and wastewater districts, including the neighboring 1 MW dual-axis tracking system at West County Wastewater District in Richmond, Calif., stepped in.

DRI Energy engineers were faced with two challenges: trying to accommodate a previous design that ultimately proved unworkable; and two on-site power generation systems that could not be interfered with. The cogeneration systems feature sensitive controls and protective relays that the solar system could not interfere with in the event that PG&E power was to go down. DRI Energy design engineers custom designed a fiber optic-based interlock to immediately shut off the inverters should PG&E power go down. The project was completed on time and on budget.

“We see a lot of projects in the industry fail to make it off the ground due to a variety of factors that include an inability to obtain project funding, design challenges, or the lack of team expertise,” said Bob Powell, president and CEO, Solar Power Partners. “Partnering with experienced firms helps negate future problems. From the start of our partnership, Oro Loma District management and the Board of Directors have been supportive and positive.”

The solar Power Purchase Agreement enables Oro Loma to buy the electricity at a contractually fixed rate at a discount to existing utility rates. This helps the district minimize expenses and rates which are now the lowest in California.

Oro Loma provides wastewater collection and treatment as well as solid waste and recycling services as a special district of local government. It encompasses 13 square miles, serving the communities of San Lorenzo, Ashland, Cherryland, Fairview, portions of Castro Valley, and the cities of Hayward and San Leandro.

Source: DRI Energy

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