When solar panels operate under full sun they can easily reach temperatures more than 60 degrees Celsius. High temperature will reduce panels' output and shorten their lifespan. For typical silicon solar panel, every degree increases in temperature, about 0.5% drop in output power. For example, if a rated 250 watts of solar panel is operating at Kota Kinabalu, Malaysia, you will only get about 206 watts of output. Using coolant or ventilation to cool the panels is expensive and energy intensive.
Scientists from Stanford University, U.S.A., have developed a passive cooling technology by adding a tiny pyramid-shaped silica glass structures to the surface of ordinary solar cells. The pyramid will help to shepherd away unwanted heat and reduce panel's temperature.
"Silica is transparent to visible light, but it is also possible to fine-tune how it bends and refracts light of very specific wavelengths,” said Prof. Fan, who led the research. “A carefully designed layer of silica would not degrade the performance of the solar cell, but it would enhance radiation at the predetermined thermal wavelengths to send the solar cell’s heat away more effectively.”
The team has tested different shapes and sizes of the structure. They were able to fine tune the shapes to refract and redirect only the unwanted infrared wavelengths (wavelengths that will heat up the panels) away from the solar cell and back out into space.
Their next step is to demonstrate radiative cooling of solar cells in an outdoor environment.