Should you pay to have your solar energy system cleaned?

Purchasing and installing solar panels for your home is one thing, but equipment maintenance is another concern. As the solar panels continue to be exposed to the outside weather – scorching heat, sunlight, rain, and dust – the panel surface will eventually get dirty. But before hiring someone to clean the solar panels, take heed from this recommendation from a group of researchers.

A recent study by the University of California, San Diego concluded that cleaning solar panels regularly may not be a wise financial decision. The study looked into data on residential solar panel outputs from the California Solar Initiative within the year 2010, as reported in a news release. The panels, identified from various residences and commercial buildings between the San Francisco Bay Area and the United States-Mexico border, were monitored in terms of electricity output during the rainy season and in the summer dry spell for that year.

The research team, composed of engineers from the university, found that solar panels in California that went uncleaned for 145 days during the summer months had reduced efficiency of only 7.4 percent. This means that a typical home that uses a 5-kilowatt solar absorption system would only gain a measly $20 in generated electricity if they chose to have the panels cleaned midway through the summer.

“You definitely wouldn’t get your money back after hiring someone to wash your rooftop panels,” said study lead author Jan Kleissl, who also teaches mechanical and aerospace engineering at the university.

Meanwhile, study co-author Felipe Mejia said that the dirt deposited on solar panels during a dry season following the rainy months does not significantly affect the panel’s efficiency.

“Dust on PV panels does make a difference but it’s not a big enough factor in California to warrant cleaning,” Mejia added.

The researchers were quick to point out, however, that the orientation of the solar panels may affect the level of dirt – and, consequently, the effectiveness of the energy production. For instance, panels installed at steeper angles have decreased energy losses because this orientation allows the dirt on the panel surface to slide off naturally.

Bird droppings are a different matter, though, because these materials are not washed off easily by rain. As a result, sunlight is blocked from being accessed by solar panels, thereby decreasing efficiency. If your solar panels are covered in bird droppings you would benefit from having your solar panels cleaned.

[Photo courtesy of Sonny Abesamis on Flickr]