Its always been a problem to me on how to get all the algae and dirt that gets trapped between the roof and solar panel. That was until a customer recently gave me one of these as he was giving up motorhoming. I have tried lots of different methods with varying results and this has to be the best, just wet it in the bucket and it being 31" long is more than long enough to reach under all the solar panel. OK its a bit expensive and some may be put off by the price but for me always wanting to achieve the best for my customers a Flatmate will always be part of my valeting kit.