what are the maitenance costs and how often do you need to climb onto the roof to clean then?
“what are the maitenance costs and how often do you need to climb onto the roof to clean then?”
Fair point. Not having had one (yet) I can’t say. Looking at the web, I’d estimate every 2 months or so. There are also other factors working against my (optimistic) ROI, such as cells degrading (they lose something like 1% per year...which adds up), and possible hardware failures and/or breakage.
Just from looking around a bit, it looks like the losses from dirty panels are 10% to 25%, with the higher numbers being in dusty areas. So, for myself, I’d like just bump up the size of the system by 10%, and eat the losses for a while, and clean every two years or so. There is a limit to how long you can get away with that because if the dirt gets concentrated in one area, that can cause permanent damage to the panel.