With the price of solar cells dropping dramatically over the last three years, you'd think solar cells would be popping up all over the place. But, they still have some fairly major efficiency problems, especially in mid-to-high latitudes or areas that see frequent cloud cover.
That may be about to change thanks to the brain trust at MIT. Instead of relying on the traditional technique--where installers aim flat panels at the southern sky--the team at MIT used computer modeling to design three dimensional panel arrays that are optimized for collecting the most energy. Even after throwing out the designs that would be difficult, expensive, or impossible to manufacture, the new vertical panel designs showed significant improvements in collection on cloudy days, compared to the horizontal surfaces. Unfortunately, the full paper is hidden behind a paywall, but MITNews has a good summary.