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Do Solar Panels Need to be Cleaned?

A year ago we installed roof mount solar panels.  We are now hearing talk that for solar optimum performance the panels should be cleaned.  Is this true and if so how often?

Dirt, dust and debris can certainly accumulate on your solar panel surface, blocking some of the sunlight and reducing output. Not being a student of mechanical and aerospace engineering, I would not even know how to begin to compute the overall efficiency of kilowatts lost vs. electricity gain during a drought vs. washing the panels and then analyzing the data of solar output with dirty panels vs. clean panels vs. the amount to clean the panels. I would say that dust on photovoltaic panels does make a difference because it would seem to me that solar panel cleaning is not any different from cleaning the windshield on our car or for that matter our eye glasses.

I talked with Zak and Lynette Hoyt, owners of The Solar Scrubber, a local solar panel cleaning company. Zak agreed that pollution, dust, bird droppings, particulate matter from construction and traffic certainly can build up over time and can all contribute to prevent sunlight from reaching the solar cells. Zak said that “industry reports indicate the lack of scheduled cleanings can cause solar panels to lose 7-20% of their efficiency and increase a solar cells buy-back time by 3-5years.”

Dirty solar panels do not produce as much power as clean panels so what should you do?

Zak said he is frequently asked “Can’t I just hose off my panels?” If you hose off your windows are they actually clean? No is the answer. And more importantly, the hard part is reaching the panels. It is extremely difficult to spray a garden hose onto solar panels from the ground and you are using hard water which contains minerals and will cover your panels with water spots, nor does a garden hose have the pressure to remove most environmental contaminates. Power washers are not recommended due to too much pressure. Solar panels should be cleaned by hand with warm water and a cleaning product to remove any accumulation of grime and dirt. Solar panels should be cleaned early in the morning, late in the day or a cloudy day is the best. This prevents any build-up of hard water molecules.

Professional solar panel cleaning companies such as The Solar Scrubber not only clean the panels, but at the same time they perform an inspection of the system for any problems or issues that might have developed, such as loose connections.

A word to the wise as Zak said, “If you have solar panels and are having your home painted it is important to make sure the panels are covered prior to painting.” Zak said he has cleaned many panels with paint overspray and in some cases the paint could not be removed. It is possible the warranty could be affected with paint overspray.

Solar panels are covered by a protective glass coating, just like our eye glasses and car windshields; they do get dirty and need to be cleaned. So make sure your system is operating properly and have them inspected at least 2x per year. If you have any questions give Zak a call at The Solar Scrubber (928) 308-4970.

Phone: (928) 778-0040


810 E. Sheldon Street, Prescott, AZ 86301

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