Panels have a low albedo - they absorb a lot of energy. About 25% of that is turned into electricity, the rest heats the panel. So as soon as a corner is expose

Panels have a low albedo - they absorb a lot of energy. About 25% of that is turned into electricity, the rest heats the panel. So as soon as a corner is exposed to the sun, it tends to melt off the rest of the snow comparatively quickly.