The company plans to purchase solar electric systems from BP Solar, SunEdison LLC and SunPower Corp.'s PowerLight business. The project covers 22 Wal-Mart and Sam's Club stores and a distribution center in California and Hawaii.

Wal-Mart estimates the solar systems will supply up to 30 percent of the stores' power usage. The project is part of the company's broader effort to cut emissions of greenhouse gases, which are blamed for global warming.

The project should also reduce energy costs, the company said.

"Pilot project stores are expected to achieve savings over their current utility rates immediately," said David Ozment, Wal-Mart energy director, in a statement.

Separately, SunPower said it had been selected to outfit seven of the Wal-Mart stores in California, adding to three others the company has previously equipped. The company's shares jumped more than 3 percent following the news, then eased 66 cents to $57.68 in midday trading.

Privately held SunEdison will provide four systems in Hawaii and four in California.

BP Solar, a division of oil concern BP PLC, will supply seven systems in California. Shares of BP slipped 12 cents to $68.39.

Wal-Mart shares rose 44 cents to $48.71 in midday trading. Copyright 2007 Associated Press. All rights reserved. This material may not be