[quote=flu]How often do solar panels need to get cleaned. I am assuming not that often?[/quote]
I tested this once a couple years ago. The following is mostly not scientific.
I waited for two sequential identical weather days in June (temperature, humidity, cloudless, duration of sunlight on array, etc.) At the end of day 1, I got up on my roof and thoroughly hosed off my panels. The result was ~ 8% increase in generation on day 2, which for my system was about $0.32 / day of electricity.
No telling how fast the panels would get dirty again, probably pretty quick in the summer, meaning you’d have to get up there kinda often if you were OCD about it. I decided that’s not worth my time and safety (walking around on my roof), and the winter rainy season was sufficient.
