Do Solar Panels Need To Be Cleaned?

Among the many advantages of solar panels are the low maintenance costs associated with the technology. Photovoltaic (PV) panels have no moving parts, and the relatively mild weather in Southern California means they’re almost never subjected to extreme conditions such as high winds, thunderstorms or hail.

For many years, the solar experts at AMECO Solar have recommended that our customers clean their solar panels by merely hosing them off a few times a year. This easy cleaning process combined with the intermittent rain of the area typically cleans the panels enough to keep the solar system running at high efficiency.

However, many solar panel cleaning companies are now selling more thorough cleaning services. They argue that if dust and dirt accumulates on the solar panels, then they will become less efficient in converting sunlight to electricity.

A team of engineers at U.C. San Diego recently called this assumption into question. They studied the efficiency of solar panels for homes that had not been rained on for a period of almost 5 months during a drought, versus those that were cleaned regularly. They found the systems that had not been cleaned or rained on for a 145 day period lost only .05 percent in daily power output. In comparison, those who had washed their solar panels at least once during this same time period ended up saving owners about $20.

“You definitely wouldn’t get your money back after hiring someone to wash your rooftop panels,” Jan Kleissl, a professor of mechanical and aerospace engineering at U.C. San Diego and the principal investigator on the study, said in a news release on the solar research.

The study focused on smaller residential solar systems. Kleissl pointed out that owners of larger commercial solar panels might see more gains from routine cleaning, as these systems typically produced thousands more kilowatt hours more than a residential rooftop array. There was little indication that hiring private contractors to clean panels would be worth the cost, unless you live in an area regularly exposed to soot or petroleum residues that would cause collectors to soil more profusely than those tested in San Diego.

Moving forward, AMECO Solar will stick to our recommendation that our customers in Los Angeles and Orange County allow the rain to clean the dust that might accumulate on their solar panels and, if necessary, merely hose them down every once in a while. If you still think that your solar panels need a more thorough cleaning, please contact us about our per panel price.