SciAm has news of a new type of solar cell that uses both light energy and heat energy. 30% efficiency, not bad! I’d like to see this get commercialized soon. Nuclear power is about 30% efficient, and high efficiency triple junction solar cells ($$$ and fragile) are 30%-45% efficient.
http://www.scientificamerican.com/podcast/episode.cfm?id=single-device-captures-suns-light-a-11-04-06