Doesn't seem like that would matter once covered by a few inches of snow. But otherwise your points seem solid.
They work better in the summer, but provide most of the house power. Doesn't help much with the EV she got since except in the summer. She got a electric water heater as well.
But once it’s deep enough it stops.
IDK if you live in a place that sees significant snow, if so, just drive around a neighborhood and notice what the snow looks like on the rooftops. Generally none on the top and some on the bottom. That's by design.
While the bottom of the panels aren't doing anything to melt the snow, the top portions are, and that accelerates as the snow melts.
This is definitely not how snow on roofs work. Here is an example with a roof with lots of snow on it:
https://millworksconstructionservices.com/wp-content/uploads...
Roofs in cold climates are designed to hold the weight of snow on top of them.
ETA:
The no snow on top but some on the bottom is because their attic isn't insulated well enough. Ideally you lose no heat through the ceiling into the attic. But without enough insulation you will lose a significant amount and the hotter air will rise to the highest point and melt the peak first. You don't want this because the melted snow can run down your roof and freeze again on the colder parts.
https://www.atozroofingdenver.com/how-does-roof-pitch-affect...
