Three years ago we put solar panels on the only part of our roof that got sunlight, which unfortunately mostly faces WNW. Since then, however, our neighbors have removed a large tree just east of us, and now the part of our roof that faces ESE gets lots of light. So I'm back to thinking about solar.

This roof is a good candidate for solar, with one problem: the panels might avalanche snow onto the neighbor's car:

The standard approach here is to put snow guards on the panels or the roof with the goal of holding back, slowing down, or breaking up the snow. In this case, however, I don't want the snow to stay on the roof and I don't mind it falling next to the house. I just need it not to fall out from the house, into the neighbor's driveway.

Is this a solved problem? Alternatively, is there something you can attach to the roof to redirect the snow straight down? Something like:

Alternatively, people who've tried snow guards, how well do they work? Are they going to keep the snow from squashing the neighbor's car, and the neighbor?