The New York Times has a report on the new trend of massive retail chains, including Safeway, Whole Foods, and Wal-Mart, installing solar panels on their store roofs to generate large-scale electricity. Their motives, of course, are the big juicy tax incentives that Congress has implemented to urge major retailers to transition from coal-based electricity to solar. Many of these stores use huge amounts of electricity, and solar panels won't be enough to eliminate the need for coal entirely. Still, experts estimate that, on a good day, the roof panels could generate 10 to 40 percent of a store's total power. But one of the most important details of the piece is buried towards the end: the fact that the tax credit for renewable energy—an invaluable credit that Congress has struggled to keep afloat—is getting held up yet again because of the deadlock over offshore drilling. So not only is offshore drilling not a solution to our energy problem, but it’s actually getting in the way of a huge source of government support for solar energy. Which could make all those retailers pretty upset if they invest in boatloads of solar panels only to be told that the tax credit doesn't extend into 2009.