Thanks Steve.
So just to be clear on what you are saying - the coating on the panels that makes them self-cleaning breaks down over time?
Some panels are coated in the same way that new windows are coated when they are sent out. It serves little other purpose than to make them look clean an shiny.
Some panels are coated to make them hydrophilic and hence, self cleaning. However, this coating breaks down over time.
Remember though that just because the panel has the coating and potential to be self cleaning, doesn't mean it is. The conditions need to be perfect for the chemical reaction to occur, which it rarely does.
