We had a light snow storm of only a couple of inches, and it got very cold. The temps have not raised above 24 f for 4 days. After seeing no panel melting after a full day of sun, I took a long window washing pole and tried to clear off some of the panels to see if simply exposing the black panels would raise the temp enough to melt the rest. It helped, but as this photo shows, the only way the full array would be making power would be if it was fully cleared. Only found one German design on the web for a snow clearing system, but it is nearly as expensive as the panels, and not available here.
snow removal and washing system

I can see how for an off grid system in this climate, with a not very steep roof slope like mine, that this could be the difference between having charged batteries after a storm induced power outage or running out of battery charge even with the sun out.
Another project for my list.
Assuming that the system could be made inexpensively enough, it could be the beginning of a nice product for all the rest of the people in this type of climate with similar situations.