Solar panels on the roofs of electric cars is a natural fit but i guess we like sun roofs too much.
It's not like you can't put solar panels on car roofs, or like it never makes sense or anything.
It might be somewhat useful sometimes.
But most cars don't spend enough time on the sun. And in some places leaving a car in the sun means having a hard time getting into it (because it gets too hot), and then wasting a lot of energy for air conditioning.
Many cars are parked in closed garages (they say this extends the life of the car, maybe it depends on the climate or the brutality of the passers by).
When driving, cars pass through shadows, change direction and get dirt and pollution on them, which isn't ideal for PV efficiency.
And if it was me, cars wouldn't even have so big batteries, or if they had them, they'd be removable, so that you don't have to waste energy moving them for short trips.
I believe solar panels are best placed in high, sunny, fixed places, and then with a little cable and some gadgetry they can fill a car battery, no need to move the panels around.
Now if you live in a van (or you do sometimes) you may want to park it somewhere you can unfold solar panels from the roof, and get some independence and usefulness.
If it's not too much trouble you can have part of them working when folded (for instance moving), but not so important. But maybe you could just save them inside the van and unfold them on the floor next to it when parked.
What I mean is that if you really like sun roofs too much, don't worry, enjoy them.