Anyone ever lose a solar panel off the roof?

No, but a racing stripe might look pretty cool.

so RVers do add spoilers in front of their solar panels in case they are traveling 65mph and have a 40mph headwind?

Airplane lift = Bernoulli's Principle Since a typical solar module is the same size on the bottom as the top, and air traveling underneath is turbulent and not extremely compressed, I doubt there is much lift. There may be down-force.

No idea about your spoilers attached to the mounts. Most guys use aluminum angle for attachment, either screwing into the top deck and/or the joists or applying VHB tape (good solution for fiberglass or aluminum roof material).

Thanks, good to know that no one has lost one and caused damage or an accident. I see that the ABS stickon mounts come with side spoilers. Does that actually cause the airflow over the panels instead of under? Isn't that what causes airplane lift?

It should take a hurricane to blow them off. At least that's what I figured when I installed mine because it's my responsibility to not hurt someone else. Four corner brackets with one wood screw and one toggle wing screw going through the plywood along with dicor. The mc4 cables would separate easily.

The cables are soldered on at best. They will tear off fairly easily.

I've not heard about solar panels falling off, mainly because they tend to be parallel to wind forces, so not that much is needed to keep them secure. However, anything can happen. I'd say that if a panel is secured at four points at the minimum, it will stick around.

I do prefer screws or rivets, but if done right, adhesive mounts can't hurt either.

I've never heard of it on here. I doubt the cables would prevent its flying off.