What happens when it gets hit by a bit of flying debris on the highway? Screwdriver, piece of wood, rock, etc? Do I have to call insurance to get the panel replaced? Or just hail. Can I own this car in the midwest?
If your car is being assaulted by solid objects at highway speeds so often that it becomes a serious concern to factor into your next car purchase, I very strongly suggest moving somewhere safer.
Solar cells aren't simply inert panels of glass or silicon, but circuits of cells for which damage may affect a large portion of a panel. Solar panels as it is suffer degredation and a lifespan of ~20-25 years, in stationary mounts, due to sunlight, UV, wind, rain, hail, sand, dust, stones, and other forms of degradation.
Road debris, rocks, falling tree limbs, pine cones, other vehicles, birds, insects, and more, could impact or degrade solar panels.
A chipped windshield can be filled or replaced, at fairly modest cost. Trailing-edge rear windows might have integrated defogger wires or radio aerials, generally front glazing doesn't. Solar panels are rather more fussy.
Body nicks and dings can be effectively ignored. PV damage, not so much.
If it really breaks, then you have a car just as useful as before, until you get the solar panel fixed.
Whether this is good or bad comes down to how much the panels will add to the cost.