Bloomberg BusinessWeek

Wal-Mart Stores Inc. (WMT) (WMT), the world’s largest retailer, has installed more than 150 U.S. solar projects and expects to have as much as 90 megawatts of capacity by year-end, more than Ikea Group and Apple Inc. (AAPL) (AAPL)

Wal-Mart’s San Diego store is the 100th to get solar panels in California, the company said today in a statement. The company currently has 62 megawatts of panels installed at U.S. locations, and also operates fuel cells and wind turbines at some sites.

Wal-Mart, with 4,522 stores in the U.S., expects to have 1,000 solar-powered locations by 2020, Marty Gilbert, director of energy at the Bentonville, Arkansas-based company, said in an interview. The retailer gets about 4 percent of its power from renewable sources and plans to install another 100 solar systems by the end of 2012, demonstrating that renewable energy is economically viable to businesses.