Yes, it does. Although when fully covered in snow, the panels blackout. But once the snow stops, it will start melting very rapidly on the surface of a solar panel. When the panels are slightly covered with snow, they usually work at 30% of their rated power.
If the environment around the solar system is fully covered in snow, then that actually enhances the system performance as it increases the light reflected to solar panels.
Even if you do get continual heavy snows in your area, during daytime for very long periods of time in winter, that has very minimal effect on the overall performance of your system.
So the bottom line is, don’t be put off to if you live in a snowy area.
Read the academic research of the effect of snow on solar panels here:
Prediction of Energy Effects on Photovoltaic Systems due to Snowfall Events
Rooftop solar systems are generally of little harm to the roof, especially if non-penetrating racking system is used. The question of protecting your roof is only relevant to the subject of flat rooftops.
Recently there’s a general tendency in the industry, both by the system installers and system owners to use protective mats under solar systems. If you are considering penetrating racking then using protection can be a little difficult. On the other hand, protective mats lay nicely and easily under non-penetrating rackings on flat rooftops.
There are few materials that are used as sacrificial layers for the roof. The most common are EPDM sheets that are widely available. These are reliable solutions and are very easy to be laid on the roof, and fall in the middle of price range for protective mats.
Other options include polystyrene foam sheets and modified bitumen. The former might no withstand outdoor environment in the course of twenty years, although being cheaper compared to other materials. Modbit might a little more expensive, and not as available as EPDM.