DailyTech reports Stanford researchers are developing a new type of gallium-based photovoltaic panel that can convert both light and heat energy into electricity. The team expects to hit a 50 to 60 percent efficiency, and they also claim that these cells should be competitive with oil-based energy generation.
To create a solar cell that would flourish under both light and heat, they broke away from the familiar silicon semiconductor platform and instead looked to gallium-based photovoltaic surfaces. But in order to harvest the heat generated by the waste energy, they needed to add an additional layer of material, for which they used a thin coating of cesium metal. They have dubbed the energy harvesting process PETE, for Photon Enhanced Thermionic Emission.
Unlike traditional silicon cells, Melosh's group's don't hit their peak efficiency until temperatures in excess of 200 degree Celsius--well above the point where silicon cells have already been rendered inert. To make the best use of the material's properties, they could be used in solar concentrators, where temperatures regularly exceed 800 degrees Celsius. Further waste heat could then be used in thermal exchangers, much in the same way solar heat is currently harvested to create energy.