Sure, but with a couple inches of snow on them, mine still generate power. And in areas which regularly receive snow, roof pitches are generally steep enough to encourage it to slide off else the building would suffer overloading. Worst case a push broom or squeegee with a very long handle works wonders.

Also fairly trivial to rig up a resistive heating system for melting the snow in cases where the above isn't possible. Even possible to automate it based on time of day and expected power input.

It does happen occasionally, but it's rare that my panels are covered for more than a day or so. Heavy snows almost always slide off within 36 hours - sometimes a light snow (~3" or so) can cover it for a while because it's not heavy enough to slide off from gravity. The panels are very low friction compared to a normal roof.

Yeah - When covered in even a moderate amount of snow, output drops almost all the way off. I had thought that being black, they would melt off quickly, but that doesn't appear to be the case. As an aside, my daughter's neighbor has solar and after a big snowstorm, a foot of snow slid off his panels, right into the side of her house destroying a basement window and blowing shattered glass 5 foot into the basement.