Do solar panels need to be cleaned? Here are some tips:
Solar Pool Heating Panels
Solar pool heating panels do not need to be cleaned. Rain does the work for you. They operate efficiently even if there is a little dust on them. The one thing that you should look out for is leaves, pine needles, and branches. These can build up above the top header and occasionally under the panels. There is really no impact on performance or longevity of the panels, but decaying plant matter could discolor your roof or cause some algae or mold growth. If you are comfortable on the roof, you can get up there an manually remove what you can with gloves, or possibly use a leaf blower. If you have a service agreement with your solar dealer, they should do this for you. If not, for the price of a service call they should be able to clean things up for you. Most systems never have a leaf buildup problem.
Solar Electric (Photovoltaic) Panels
The same debris possibilities exist with PV panels, but typically there is enough room underneath panels for debris to blow or fall off the roof eventually. Module soiling can be a problem if you have lots of birds around your roof. Dust can build up, too. The good news is that rain typically is enough to wash the panels off. The glass surface is specially coated and very slick when wet. In the dry season, if you notice heavy buildup, spraying the modules with a hose is usually enough. In the summer around Southwest Florida, almost daily afternoon showers do good work to clean panels. If you have a heavy soiling problem, use a soft boat brush to gently brush off debris with water only. Do not use soaps and detergents, and never use harsh chemicals. Your solar dealer can schedule a service call if your panels are hard to reach or if you do not feel comfortable on the roof.
If you have Enphase Microinverters, you can check your web monitoring to see if any panels are under-performing. This could be an indication of a panel that took a direct hit from a bird bomb!
Note: always follow the panel manufacturers cleaning instructions.