Wal-Mart yesterday unveiled a solar power system on the roof of its Sam's Club Ke'eamoku Street store, the first of four such systems it plans to install at its stores in Hawai'i this year.

The system was financed, constructed and will be maintained by SunEdison LLC, a Maryland-based solar power company. Wal-Mart will purchase the electricity from SunEdison under a solar power services agreement. Sam's Club occupies the second floor of the Wal-Mart location.

Wal-Mart and SunEdison will team up on similar projects this year at Wal-Mart stores in Mililani and Pearl City on O'ahu and in Kailua, Kona, on the Big Island. The four locations are among 22 Wal-Mart stores, Sam's Clubs and distribution centers in Hawai'i and California that are getting solar systems under a pilot program. Wal-Mart and Sam's Club are owned by the same company.

The Hawai'i systems, on average, are capable of generating 10 percent to 15 percent of the power needs for the stores, Wal-Mart said in a news release.

"We are committed to making decisions that are good for business and the environment," said Brian Halsey, manager for Wal-Mart in Hawai'i.

During the first year, the rooftop system will produce an estimated 444,000 kilowatt hours of solar energy, Wal-Mart said in a news release. During a 10-year span, the system will produce an estimated 4.2 million kilowatt hours of solar energy and reduce greenhouse gas emissions by 7.3 million pounds.

SunEdison, based in Beltsville, Md., also has installed similar systems on the Big Island for Island Naturals Market & Deli in Pahoa and two Toyota dealerships.

"Wal-Mart's decision to use renewable energy proves zero-emission solutions are viable right now, and that solar power is clearly a part of the energy mix," said Thomas Rainwater, chief executive officer of SunEdison.