The Salt River Project has switched on Arizona's largest solar-energy array, a 144-acre, 20-megawatt installation in Florence.

The Copper Crossing Solar Ranch, on the west side of Florence, will initially provide power to more than 100 schools in 11 Phoenix-area school districts. The schools are participating in SRP's EarthWise Community Solar program, which allows customers to essentially buy power from utility-scale solar installations.

SRP is a quasi-governmental water and power authority that serves about 940,000 electric customers in the Phoenix area.

Copper Crossing, which provides enough power for about 3,700 SRP customer homes, is the largest of its kind in Arizona and the first solar plant built by Iberdrola Renewables in the United States.

The array, comprising about 66,000 high-efficiency photovoltaic panels manufactured by SunPower Corp., will use very little water, SRP said.

The school districts will purchase a total of 7,840 kilowatts of solar energy from the plant for a fixed price for 10 years. The solar installation will reduce carbon emissions by an estimated 575,000 metric tons over the next 25 years, SRP said.