Indeed, I can tell when the grasses start getting too tall as my solar input drops for sure.
Yeah I should clean them every so often. Its been about a year since they were cleaned last. We get some hail once in awhile and that tends to clean them.. Just hoping they do not get too big and crack the glass.. lol
I assume rain will clean off most of the dirt. We had a tiny bit of snow over winter, but it didn't really cover them. Not that they were generating so much anyway then.
I've not check what sort of hail they would withstand, but we rarely get it very big.