It’s not a solar company, it’s Walmart or IKEA, depending on how you look at the data in the new report, “Solar Means Business: Top Commercial Solar Customers in the U.S.” The report, by the Vote Solar Initiative and Solar Energy Industries Association (SEIA) found that across the U.S. commercial entities, including nonprofits and governments have installed 2.3 gigawatts of photovoltaics as of mid-2012.

The organizations used public databases and contacted company representatives to gather the information in the report. “This is our first ever review of this,” said Rosalind Jackson, Vote Solar’s director of communications and development. The research may not include every commercial system in the U.S., since there is no absolute clearinghouse of all installation data in the U.S. However, they made the best effort to collect all data they could. It also found that during the first half of 2012, over 3,600 commercial systems came online in the U.S.

The majority of those systems are installed on some of the best-known brands or companies in the U.S. In terms of overall capacity (from most to least) the top 20 companies are: Walmart, Costco, Kohl’s Department Stores, IKEA, Macy’s, McGraw-Hill, Johnson & Johnson, Staples, Inc., Campbell’s Soup, Walgreens, Bed, Bath & Beyond, Toys ‘R’ Us, General Motors, FedEx, White Rose Foods, Dow Jones, Snyder’s of Hanover, ProLogis, Hartz Mountain Industries, and Crayola.

Walmart, by far has the most in terms of both capacity and number of sites with solar. Over 144 stores the company has installed a total of 65 megawatts of solar, the report found. With 38.9 megawatts installed Costco was the second in terms of capacity, but with 62 systems installed it was fourth in terms of overall installations. Walgreens was second in terms of number of installations at 134 installations, but since the company’s stores are generally much smaller than Walmarts or Costcos, their generating capability is much less at 8.2 megawatts, putting them at 10th place for capacity. In terms of percentage of facilities with solar IKEA was first with installations online at 79 percent of its U.S. sites. The next closest entity was REI, which had solar at 20 percent of its U.S. sites.

The leaders could change quickly, according to Jackson. “We do expect that next year there will be some shakeups. There are a lot of companies that have announced plans.” Among them Apple, which is adding a massive solar project at their data center in North Carolina. “Their data center would knock them into the top five,” she said.