Washing solar panels is sometimes recommended by some third party companies but it involves monetary and environmental costs.
Is it beneficial? I compared the ratio production over insolation the week before and after a friend washed his labels for the first time in 5 years and I couldn't see any meaningful difference.
Is it needed to ensure their long life? Are there studies about it?
And is it mandatory to ensure that insurances will pay in case of damage by fire? In my contract the insurance states that regular maintenance should be performed but there's nothing in the documentation by the company providing the panels about it.