The retail giant at the end of last yearto suppliers soliciting bids on what could be a large-scale installation of solar electric power at company stores.
Responses to bids, initially expected at the end of February, are being delayed, according to two people with knowledge of the situation.
One company bidding on the deal said Wal-Mart's decision has been put off four to six weeks, which would put the date for bid responses in April.
"I'm actually not too surprised. They only gave themselves six or seven weeks to evaluate some very complex proposals covering stores in multiple states," an executive at a solar provider said. "They're smart to take their time."
A Wal-Mart representative on Tuesday declined to provide further details on the company's solar-power request for proposal.
The company's moves in renewable energy are closely watched because of its sheer size and its stated commitments to environmentally friendly practices.
Clean-technology consultant Joel Makower, who saw the original proposal, said in a blog in January that the investment could represent , dwarfing other well-known corporate solar-power installations.
Wal-Mart has a long-term policy headed up by Andy Ruben, vice president of corporate strategy and sustainability, of using 100 percent renewable energy.
Another goal stated by Wal-Mart CEO Lee Scott is to make its stores 20 percent to 30 percent more energy-efficient.
The company has two experimental stores--in McKinney, Texas, and Aurora, Colo.--that use renewable power sources including solar and wind. In January, it opened four high-efficiency stores designed to serve as prototypes for the clean-energy initiative, according to the company.