Retail behemoth Walmart has invested in installing more solar energy systems than any other US company, with its total generating capacity standing at 65,000 kW, 67 percent greater than that of its nearest rival, Costco. The figures come from a new report by the Solar Energies Industry Association (SEIA), which shows retailers leading the way in the environmentally-friendly field — in terms of total generating capacity, third place goes to Kohl's, fourth to IKEA, and fifth to Macy's.

As GigaOm points out, the large amount of roof space afforded by big retail stores makes them ideal for solar panel deployment, while the overall boost in solar energy investment in recent months can be attributed to extremely low equipment prices and attractive subsidy deals from federal and local government. According to the SEIA, "during the first half of 2012, over 3,600 non-residential PV [photovoltaic] systems came online, an average of one every 72 minutes."