A team of researchers at UC San Diego Jacobs School of Engineering carried out a study in 2011 to examine the cooling benefits of rooftop solar modules using thermal imaging. The researchers found a building's ceiling was up to 5 degrees Fahrenheit cooler under the array than under an exposed section of roof. Additionally, the panels can help keep heat in at night during winter.
Jan Kleissl, a professor of environmental engineering who led the research, says his team has determined the savings through a solar panel's insulation qualities amounts to a 5% discount on the cost of the modules over their lifetime.
The panels act as shades, preventing the the sun from beating down directly onto the roof. While solar panels do heat up, much of the heat is removed by air movement between the panels and the roof. The greater the gap, such as would be found in a tilted array, the greater the benefits. The team also found the more efficient the solar panels are in converting sunlight to electricity, the bigger the cooling effect, as heat is a by-product of inefficient conversion. In the team's tests, the panels reduced the amount of heat hitting the roof by about 38 percent.
While Professor Kleissl acknowledged there are of course more efficient ways to insulate buildings, it's just an added energy efficiency bonus through installing a rooftop solar power system.
The results of the testing show a rooftop solar array's insulating qualities are a side benefit substantial enough to be taken into consideration when making a purchase decision. It's this characteristic that also further bolsters the case for turning the sea of rooftops in our towns and cities into massive distributed electricity generation systems to help reduce the load on centralized power generation.
Additional benefits of a decentralized electricity generation system with solar power as the centerpiece are a reduction of infrastructure investment by network operators and lessening line loss associated with power transmission; which can account for up to 10% of electricity production. Solar panels also generate their peak electricity during major consumption periods; so with greater uptake, fewer fossil-fuel burning peak power plants would need to be constructed.