City’s shining example of solar power

The City of Sonoma unveiled its first solar power system Wednesday, a grid of shiny panels atop the Sonoma Police Station.
The photovoltaic system will offset nearly 70 percent of the annual bill for the Police Department and the other facilities at the 175-177 First Street East structure, the Community Meeting Room and the Emergency Control Center.

With the $389,000 solar electric system in place, the city projects on-going annual savings in utility costs of $11,836 per year. Additionally, any excess power generated during the day will be fed back into the PG&E grid for credit toward future use.
The roof-mounted system utilizes solar panel that cover 4,900 square feet of the south-facing roofs. They help shade and protect the building, reducing the summer cooling load.

The system, engineered and installed by Sonoma and Novato based SolarCraft, is expected to generate 89,000 kilowatt hours annually. SolarCraft President Bill Stewart said the output is enough electricity to power more than twenty average homes, as well as sparing the air of approximately 57 tons of harmful greenhouse gases, every year.

This reduction in carbon emissions is also significant, Stewart said. The system is comparable to planting nearly sixteen acres of trees, or more than three million miles of avoided driving over the 30-year life of the system.
Though its bid was not the lowest for the job, SolarCraft’s unique design offered something the other project bidders didn’t, Stewart said. Unlike more conventional solar electric systems, the Sonoma unit will produce at full capacity no matter how many panels are shaded, greatly increasing overall efficiency.

Part of the system’s cost will be offset by a rebate from the California Solar Initiative, estimated to be $105,976 over a five-year period. The city also took advantage of zero interest bonds that were available to help cities and public agencies move to more sustainable energy solutions.

The Police Station project included an upgrade of the emergency generator. The previous unit was found to be inadequate to meet the city’s emergency operations and response needs.

A new diesel-powered generator and associated switchgear equipment has been installed by Gwinn Construction of Auburn. It is capable of automatically transferring and supplying emergency power to the entire facility for approximately 30 hours without refueling. 

The generator is synchronized with the new solar array to provide necessary safety measures. The $329,990 cost for the project was on budget and paid for using the unused balance of 2003 bond funds.

“The upgrades will both reduce the ongoing operating costs of the building, and meet the disaster preparedness and emergency services needs of the community,” said City Manager Linda Kelly in a statement.

Neither project was a general fund expense, Kelly said, nor both “will serve the needs of the City and its residents for many years to come.”