Pure Water
Purified water has all contaminants removed from it and is trying to return to its normal state by absorbing available particles from its environment, ie. your windows or solar panels, effectively removing the dirt. As the water supplied to rinse the surfaces is also pure it will not leave streaks or spots as it dries, thus eliminating the need to use traditional methods of a squeegee or other wipes. Using it in water fed pole systems with a reach of several meters it makes detergents and ladders obsolete.
