Wal-Mart to double amount of solar energy use

— -- Now, it's offering a bright spot in a wobbly renewable energy market.

Wal-Mart plans to announce for Earth Day on Wednesday that it will as much as double the size of its solar-power initiative in the next 18 months by putting rooftop solar arrays on 10 to 20 stores and distribution centers in California. The retail giant early this month finished installing solar setups at 18 Wal-Mart and Sam's Club stores and two warehouses in California and Hawaii.

"(Wal-Mart) is something of a bellwether," says analyst Nat Bullard of New Energy Finance.

The U.S. solar market showed healthy first-quarter gains in an otherwise bleak renewable energy industry, though some experts say that largely resulted from a 2008 order backlog.

All of Wal-Mart's solar projects will generate enough clean energy to power the equivalent of 2,600 homes and avoid 22,500 metric tons of carbon-dioxide emissions each year — tantamount to taking about 4,000 cars off the road. The company is considering other sites for solar arrays.

As with the first batch of stores, Wal-Mart won't buy the solar setups outright. Under a 10-year power purchase agreement, or PPA, it will pay for the electricity it uses. BP Solar will make, install, own and maintain the systems.

Wal-Mart aims to buy the green power at prices equal to or less than traditional energy. The chain already has reaped a "moderate savings" with the initial projects, says David Ozment, Wal-Mart's energy director. Each store gets 20% to 30% of its power from solar.

"The pilot program led us to the point that we believe in solar," says Kim Saylors-Laster, Wal-Mart's vice president of energy.

A good time for solar?

The project is part of an aggressive environmental campaign Wal-Mart unveiled in 2005. The chain is among a bevy of retailers that announced solar projects the last two years, including Target, Macy's and Whole Foods. Most signed PPAs, which have exploded in recent years because they let large businesses buy solar energy without huge upfront costs or, more significantly, the hassles of maintaining systems. The set-ups comprise the bulk of the large commercial solar market, says consultant Larry Sherwood of the Interstate Renewable Energy Council.