A recent article announces positive news: rooftop panels can help cool a building, in addition to powering it.
The article cites a recent study that finds that a building’s ceiling was 5 degrees cooler under solar panels than under an exposed roof and that the panels helped retain heat at night, reducing energy costs during the winter.
"Talk about positive side-effects," said author Jan Kleissl, a professor of environmental engineering at the University of California-San Diego's Jacobs School of Engineering. Kleissl’s team claims that its study is the first to show the cooling benefits of solar photovoltaic panels.
Kleissl’s research finds that solar panels can essentially act as roof shades. After collecting data from solar panels on the roof of one of the buildings at UC-San Diego, the team found that the panels reduced the amount of heat reaching the roof by 38%. The panels reduce the amount of sunlight hitting the roof, and much of the heat from the sunlight is removed by wind blowing between the panels and the roof. Benefits increase if there is a gap between the building and the panels; thus, tilted panels provide more cooling than flat ones. The larger the solar panel, the bigger the cooling effect, the article adds.
"There are more efficient ways to passively cool buildings, such as reflective roof membranes," Kleissl said in announcing the findings. "But if you are considering installing solar photovoltaic, depending on your roof thermal properties, you can expect a large reduction in the amount of energy you use to cool your residence or business."
Kleissl added that additional funding would enable his research team to develop a calculator that people could use to predict the cooling effect o f panels on their own roofs. The study was funded by a NASA Graduate Student Research Program fellowship.
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