A while ago Google conducted an experiment where they installed solar panels on the ground and left them untouched for 15 months. Then they finally cleaned them to see their power output double instantly.
The panels were installed flat though. What about PV modules that are inclined, like those on a tilted roof? In this article we’ll talk about how to clean solar panels and whether you should do it or not.
Why do solar panels need to be clean?
Google engineers have concluded that PV modules that are installed at an angle don’t need washing – simply because the rain does it all the job. However, later studies showed that it’s not entirely true. The debris that rain washes away does little harm to the efficiency of a panel – it drops by mere 2-3%. But the dust that accumulates on panels eventually turns to mud when it rains, and that brings the power output of panels down. Besides, rain is powerless when it comes to, for example, bird droppings. Thus, it is recommended to wash your panels occasionally – maybe once in a year or two, depending on the weather in your area. If you notice that the power output of your panels has gone down, maybe it’s a sign that you should give them a scrub.
Basic rules of cleaning solar panels
Washing PV modules is like cleaning windows. You can try hosing them from the ground if it’s possible to reach them. If not, you might need to climb the roof – choose a cloudy day for it. The best way to clean solar panels is with water and a squeegee or a soft brush on a stick. Try not to apply too much pressure and avoid scratching. Please, be extremely careful when getting up there and if you aren’t confident in yourself, it’s better to call for professional help.
What can be used for cleaning solar panels?
If there are stains that are too hard to remove with water, like aforementioned bird droppings, it makes sense to use cleaning products. However, before using one you have to be sure that it won’t react with the glass or aluminum frame of a solar panel. The soap isn’t recommended: when the soap water dries, it leaves a residue that raises the reflectivity of the surface. There are products on the market that are designed specifically for cleaning panels. If the situation is tough, they may be your solution.