A team of researchers at UCSD has competed a study outlining an often overlooked side benefit of rooftop solar panels: the cooling effect on buildings that mount them. The study, to be published in an upcoming edition of the science journal Solar Energy, was led by Jan Kleissl, a professor of environmental engineering at UCSD’s Jacobs School of Engineering.
Thermal imaging studies were conducted over a three-day span on the roof of the Powell Structural Systems Laboratory last April. Researchers concluded that portions of the roof covered by solar panels were kept an average of five degrees cooler during the day, and that the same areas also retained more heat through the night, potentially reducing heating and cooling costs. Instead of the sun beating down on the roof and transferring heat energy into the building below, the panels act as a shade, deflecting the heat. Much of that heat is then dissipated by wind when the panels are installed at a slant rather than flat against the roof’s surface, the preferred method for achieving the cooling effect.
The findings of Kleissl’s team indicate that the savings in energy used to cool a building would offset the cost of installing solar panels by about five percent. Re-phrased, it could be said that the net benefit of the panels was equivalent to five percent more energy than they actually produced. “Talk about positive side-effects,” said Kleissl.
A NASA Graduate Student Research Program fellowship provided the funding for the study. Given additional funding in the future, the group could use their data to prepare a calculator to determine the net heating/cooling benefit that could be expected in a variety of different climates.