As part of a complete energy efficiency and greenhouse gas reduction plan, Sacramento County, Calif., installed a 100 kW photovoltaic array on its Health and Human Services Building. The initiative is a key component of the county’s effort to meet its reduction goals as a member of the Chicago Climate Exchange. Sacramento County, along with King County, Wash., and Miami-Dade County, Fla., are the only county members of the voluntary, but legally binding, initiative to reduce greenhouse gas emissions below a predetermined baseline. For Sacramento County, that baseline is an average from the years 1998-2001.
But the main reason the county took on the solar and energy efficiency project is financial. “This reduces the cost of energy for the taxpayers,” says Carl Mosher, director of facility planning, architecture and real estate.
The county has a history of trying to be as green as possible and using renewable energy, says Mosher. A few years ago, the county completed a project where methane is extracted from a landfill and used to generate about 14 MW of electricity.
The Health and Human Services building is the first of what Sacramento County hopes to be many solar installations. The 100 kW array, at its peak, provides about 25 percent of the building’s 400 kW load during the summer time. During the winter, the building’s load is 100 kW or less on some weekends, says Daniel Mendonsa, the county’s energy program manager, which means that the array will sometimes pump energy back into the grid.
“Live meters tell us how much power we’re using from the utility and there’s another meter on the PVs that shows us how much we’re producing, so we can see at any 15-second pulse what’s going on,” says Mendonsa.
The county received a $300,000 rebate from the Sacramento Municipal Utility District. Mendonsa says that, with the rebates and energy savings, the payback period for the entire project — which included lighting, HVAC and other energy upgrades as well — is expected to be about 10 years.
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