Installation of the rooftop systems will start in August, with 11 stores converted this year, and the remaining 15 expected by July 2008, Joseph Venne, vice president for solar programs, told United Press International.

He would not disclose the systems' cost.

The systems, combined with energy-efficiency upgrades, are expected to save 24 million kilowatt-hours of traditionally generated electricity a year, Macy's said.

A typical home used several hundred kilowatt-hours in one month.

The systems also will cut the amount of carbon dioxide Macy's emits through the combustion of fossil fuels by an estimated 195 million pounds over the systems' 25-year lifetime.

"This is the equivalent of removing 1,144 cars from California's highways each year," Macy's said in a statement.