Now that the solar market is maturing and solar glass panels have been exposed to harsh elements for many years, people are experiencing for themselves the costly effects of exposure to the environment.
That’s because when you do not clean a panel it often gets dirty. Once there is a dirty spot on the solar glass (e.g. dust, bird droppings, moss, pollen, mildew, algae, leaves, etc.) the sun cannot shine on to the solar cells under that spot and they will no longer generate power.
Over time, a solar panel may easily lose up to 20% of its maximum power output because it is not regularly cleaned. That’s an expensive energy loss considering the large amount you have invested in your solar panels.
“A significant reduction of energy yield may occur (up to 10% after a few years). An important part of this reduction is due to the pollution developing gradually despite the cleaning by rain.”
“Depending on plant location, tilt angle and module type, a periodical cleaning of the modules may make sense to prevent a decrease in energy yield.”
“This figure shows that that Kg and thus energy yield of the PV generator decreased at first slowly, then faster and faster due to increasing pollution at the lower edges of the frames.”
“After cleaning Kg [energy yield] increased about 7% in 1998 and 9% in 2002.”
(Source: www.pvtest.ch publications: Nr. 99: "Long-term Behavior of Grid-connected PV Systems," a research study by Prof. Dr. H. Haberlin, Bern University of Applied Sciences, Photovoltaic laboratory, Burgdorf, Switzerland.