Record for solar-to-grid efficiency finally broken

This January, on an exceptionally clear and cold day, scientists for the Sandia National Laboratory and Sterling Energy Systems recorded a 31.25% solar-to-grid efficiency, nearly 2% better than the 1989 record.

The efficiency record, according to the scientists working on the project, brings us another step closer to getting solar to compete with coal power prices.

Solar-to-grid efficiency is very different than solar panel efficiency, which already has exceeded 40%. Unfortunately, getting the power from a solar panel (which is direct current) onto the grid (which is alternating current) requires several steps, each of which eats away at efficiency.

These solar collectors, which use concentrators to heat a Sterling engine, produce alternating current, so less energy is lost getting the power onto the grid.

The scientists contribute their success to (1) the increased reflectivity of the mirrors, which now approaches 95%, and (2) a rather ironic "perfect storm." This consisted of a perfectly clear day, with 0% moisture and no particulates, so the day was 10% brighter than average.

Additionally, the cold weather helped as well. Sterling engines operate by exploiting the difference in temperature between a hot end and a cold end. Solar energy heats up the hot end, but the only thing to cool the cold end is the ambient temperature.

Now we just have to hope that these solar concentrators can be scaled up, or made cheap enough to start, at least on cold days in New Mexico, to compete with coal.

Via Metaefficient