Waste heat is a problem for many systems, including car engines, power plants, and even solar cells. With solar cells the problem is not just the loss of energy as heat, but that increased temperatures decrease performance. As reported in the Optical Society's new Optica journal, researchers have found a new way to significantly cool solar cells, passively.
Sunlight is comprised of much more than just the visible light we see, and that solar cells convert to electricity. It also contains infrared light, which efficiently carries heat, and it will dump that heat onto solar panels, causing them to heat up to as much as 55 ºC (130 ºF). As even a single degree Celsius can drop the efficiency of a solar cell by half a percent, and 18 ºF can double the aging rate of a cell, such high temperatures are a problem. To address this, the researchers turned to silica glass, which is transparent to visible light, but can be shaped to manipulate infrared light. They tested both a flat layer of silica on a solar panel and a surface covered in cones and pyramids just microns in size. The more complicated surface performed significantly better than the flat surface, and nearly as well as the ideal design would.
What the complex design does is refract and redirect the infrared radiation away from the solar cell, keeping it cool. The researchers are now doing more experiments on the design and will be demonstrating their cooling scheme in an outdoor environment next.
Source: The Optical Society