Placer County has dedicated its latest solar-energy project for government buildings - a $2.4 million photovoltaic system that stretches over two acres and powers the Juvenile Detention Facility in Auburn.

The project, dedicated Thursday, is one of four solar-power systems installed at county government facilities in recent years, capable of producing a maximum of 584 kilowatts of renewable electricity.

Each system has a lifespan of 25 to 30 years and will take the county between 13 and 14 years to pay off.

"It just makes good economic sense," said Bruce Kranz, chairman of the Board of Supervisors. "Energy is never going to get cheaper. After it's paid off, you get free energy. Who wouldn't want to do that?"

The estimated value of the power generated through the county's various photovoltaic systems is $8 million over their lifespan, according to Jim Durfee, county director of facility services.