this might be a bit silly but... maybe not... could you siphon off a little bit of power from the panels to heat an array of heating wires just enough to melt snow on impact and then it'd drip off like rain?
Not at all. Afaik you won‘t even need wires for that. You can occasionally feed energy into the panels which produces a bit of heat there. It wouldn’t even have to melt (a lot) of snow - just enough that the bulk of it slides off.
That snow will then still be on the warehouse roof though.
But I wonder if some "maintenance bot" could eventually become established that's designed around the benefits of the regular grid structure. Perhaps "walking" from socket to socket like a gravity-well capable descendant of Canadarm? Wouldn't start as snowplows, but for maintenance tasks at lower frequency, large solar parks could even make very expensive units worthwhile, and from there the magic of mass market might bring prices down sufficiently far.