Always use non abrasive cleansers on your solar panels. An abrasive cleaner can scratch the surface of the panel and cause permanent damage and affect how well the solar panel works. There are commercial cleaning solutions to use or you can use a pool skimmer with a very soft cloth on it.
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Do not clean your solar panels with abrasive chemicals. You should use some lukewarm water, a soft cloth and some biodegradable soap if needed. Clean your panels at least once a month or more frequently if you notice your green energy system is not producing as much power as it should.