Self-cooling solar cells boost power, last longer
Jul 22, 2014
This drawing demonstrates how solar cells cool themselves by shepherding away unwanted thermal radiation. The pyramid structures made of silica glass provide maximal radiative cooling capability. Credit: L. Zhu, Stanford University.
Scientists may have overcome one of the major hurdles in developing high-efficiency, long-lasting solar cells—keeping them cool, even in the blistering heat of the noonday Sun.
By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society's (OSA) new open-access journal Optica.
Solar cells are among the most promising and widely used renewable energy technologies on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the Sun into usable electricity.
Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however—either by ventilation or coolants—would be prohibitively expensive and at odds with the need to optimize exposure to the Sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of silica glass, the researchers found a way of redirecting unwanted heat—in the form of infrared radiation—from the surface of solar cells, through the atmosphere, and back into space.
Read more at:
http://phys.org/news/2014-07-self-co...power.html#jCp