Yes I've got a customer who asked if I would clean her solar panels, I do them every month when I clean her windows, she has them on the roof of her barn and there are quite a lot.. I charge £15... would be more if I wasn't already doing her windows, and it takes me about an extra 5 minutes
she is really pleased as they get covered in dust and bird muck.. and after I have done them she says that they are producing a lot of extra electricity which she gets paid for!!