We offer brushes for many glass washing and processing plants and solar panel cleaning euquipemts.
For glass surface cleaning and washing, we have staple set cylinder brush and spiral wound roller brush. When producing them, we use extremely small diameter bristles, which do no damage to glass suface. 
Spiral wound roller brush and staple set cylinder brush can be also used for solar panel cleaning equipment. 
A spiral wound roller brush for this application is with light weight aluminum core and a certain distance between spirals.
Staple set cylinder brush is also with spiral tufted pattern for better cleaning performance.
More important, the bristle material has to be nylon which is soft.