How to stay cool during a heat wave? New research offers one unexpected solution: cover your roof with solar panels.
There are plenty of benefits to using solar panels—notably clean energy, long-term electric-bill savings, utility rebates, and tax incentives. But one recently discovered side effect might be especially attractive to people suffering through this weekend's heat wave: Solar panels also keep buildings cool.
A new study in the current issue of the journal Solar Energy has found that a building's ceiling was cooler by 5 degrees F under a roof lined with solar panels than under a standard roof, as the panels reduced the amount of heat reaching the roof by 38 percent.
"It's mostly that shadow effect, like when you park your car under a tree. The sun hits the solar panels, not your roof," explains study co-author Jan Kleissl, an assistant professor of environmental engineering at the University of California - San Diego. "It's very intuitive."
Kleissl, fellow UCSD researcher Anthony Dominguez, and NASA's Jeffrey C. Luvall used thermal infrared imagery to measure the temperature of the Powell Structural Systems Laboratory, which is partially covered by solar photovoltaic (PV) panels. The details of the study are of course specific to this particular building, which Kleissl describes as an "old, empty cube"—a commercial-style building that is more than a decade old and has little insulation.