In general, solar photovoltaic panels don't need a whole lot of maintenance as there are no moving parts. They usually have warranties good for 20 or 25 years. Cleaning off built-up dust and pollen in the spring or summer is a good idea because that film cuts out a little bit of light from hitting panels, reducing the amount of electricity they make.
But snow is a completely different story. A thick blanket of snow--and we've seen many of those this winter--can all but eliminate electricity production. Sure, some light can penetrate through but the panels produce just a fraction compared to their potential.Solution? Gotta get a roof rake.