Davis-Monthan Air Force Base will buy power from what will be one of the nation's biggest solar power plants, a planned 14.5-megawatt photovoltaic array to be constructed on the base, base officials said Monday.

The ground-mounted solar array, to be built by Maryland-based SunEdison, is expected to cover about 130 acres in underused areas on the base's northwest and north sides, D-M said. Construction is expected to begin in 2011. Engineers expect the array to deliver 35 percent of D-M's base energy needs. The cost of construction, to be paid by SunEdison, was not available.

Power from the solar array will be cheaper than power from Tucson Electric Power Co., a D-M spokesman said. SunEdison will design, own, operate and maintain the PV array while D-M will lease the land to SunEdison and buy the electricity generated from the array. The project is structured as a renewable -energy power-purchase agreement, which is made up of a utility contract and a 20-year ground lease, still awaiting final approval, D-M said.

The D-M project will be larger than a 14.2-MW photovoltaic plant at Nellis Air Force Base in Nevada, which was the nation's biggest PV array when it was built in 2007 and is still among the largest.

— David Wichner