Funnily enough, there was a thread a while ago here where people were fixated on the idea that you had to wash solar panels, and thus proponents are underestimating maintenance costs. I had wondered where that idea had come from, as I thought it was fairly well understood that even quite dirty panels once much of an efficiency drop…

I asked a friend with a window cleaning business and they charge about $10 a panel. At that rate I'm tempted to try it but I'm not sure if it's even worth that.

Its an easy value add for a pressure-wash / soft-wash business