So much of this discussion depends on where you are. In the US, a typical solar installation is on the pitched roof of a house. When the sun comes out, the dark roof and PV panels heat up, and the snow slides off. Rowhomes or apartment buildings in a city might have flat roofs with panels mounted on racks, but most US cities won't get enough snow often enough for this to be a problem.
My parents do have a traditional pitched roof. Winter sun is not warm enough to warm up anything, even if dark, until late winter. Plus the color of course is white if it's covered in snow :) Yeah very much location dependant.
