Researchers at the University of California, San Diego, have discovered an added benefit to solar panels: In summer, they cool the buildings on which they are installed. Using thermal imaging, the scientists found that solar photovoltaic panels act like giant sun shades and that building ceilings under the panels were 5 degrees F cooler than top-floor ceilings of buildings with exposed roofs. Reporting in the journal Solar Energy, the researchers also found that tilting the solar panels allowed for the efficient passage of air underneath, further cooling the buildings. In winter, the solar panels prevent some sunlight from warming buildings, but at night the panels trap heat and warm buildings, essentially offsetting any reduction of solar heating during the day. Solar panels reduced the amount of heat reaching the roof by 38 percent, the study said. Overall, the study said that the energy savings from the cooling effect of solar panels amounted to getting a 5 percent discount on the price of the panels.