Don’t hire someone to wash your dirty solar panels. That’s the conclusion of a study recently conducted by a team of engineers at the University of California, San Diego. Their findings were published in the July 25 online issue of Solar Energy.
Researchers found panels that hadn’t been cleaned, or rained on, for 145 days during a summer drought in California, lost only 7.4 percent of their efficiency. Overall, for a typical residential solar system of 5 kilowatts, washing panels halfway through the summer would translate into a mere $20 gain in electricity production until the summer drought ends—in about 2 ½ months. For larger commercial rooftop systems, the financial losses are bigger but still rarely enough to warrant the cost of washing the panels. On average, panels lost a little less than 0.05 percent of their overall efficiency per day.
“You definitely wouldn’t get your money back after hiring someone to wash your rooftop panels,” said Jan Kleissl, the principal investigator on the study and a professor of mechanical and aerospace engineering at UC San Diego.
He cautions that the study is focused on smaller systems. For very large installations, economies of scale may mean that washing panels is worth it.
Read more at: Phys.org