The Dutch have been working on this for ages : https://lightyear.one/

There are some, but as mentioned several times, the traditional car is too heavy for solar panels to be effective. There are some vehicles that are essentially enclosed motorcycles like the Aptera where it can be effectively used, though. Aptera can use solar panels effectively because even at their largest battery capacity, it's still significantly lighter than an EV sedan.

Look at the Fisker Ocean, it adds almost no range or energy, and leaves horrible and distracting shadows on the passengers. Youat as well ask why you can't charge a car with a D battery.

on the roof doesn't make much sense. What I did see the CSIRO testing was a portable solar array that you could roll up and store in the boot. IIRC they drove a Tesla across a large swath of Australia stopping and only charing on the portable array as needed

I don't remember what car it was but an ex's car had this. It was only really used for keeping the car from getting way too hot while it was off in the summer.

Thanks for posting the question! Whole point of the community.

I think we'll see more of this in the future as they continue to make progress on inexpensive "solar paints" and the like. It's not a bad idea, it's just that the tech level doesn't show much bang for the buck...yet.

It would increase the cost and also complicate the manufacturing process.

The materials are more expensive and heavy than what car roofs are normally made of, and the charge they would generate is miniscule. It may not even offset the added energy needed to move the car because of the added weight. Particularly if you live far from the equator, or somewhere cloudy, it's probably not worth it.

When I was a kid (in the early 00's) there were solar cars on TV and they were always these absurdly shaped pancakes made of ultralight materials and couldn't even reach road speeds. I'm sure the tech has improved since then, but the real innovation that made electric cars possible was batteries. It's hard to generate enough energy on the same platform you need to move without it being too heavy.

They have them on some international models of Hyundai electric cars. It's not nearly enough to power the car or charge the battery, though. It's more to just slow the battery down while it powers low-power things and look cool (it's part of the trim package). Solar panels need to be way more efficient than they are now for them to really make a difference with such a relatively small surface area.

I have a very vague memory of watching a video where someone calculated the amount of energy produced, which was minimal. The benefit vs the cost is very poor.

Also where I live, most cars spend a long time in underground (or at least covered) garages

https://en.wikipedia.org/wiki/Sono_Motors_Sion

The amount of power you could pull from a single square metre of solar on the roof wouldn't increase your range meaningfully.

What it would do, is that you could possibly keep your starter-battery from going dead-flat if you left your car alone for a 1/2 month, in the summer ( snow would cover it, obviously ), & since bringing a lead-acid battery to dead-flat permanently-damages it, this would prevent costly problems for the car-owners.

( this happened to a friend with a Prius: had to replace the battery, and the damned thing was inside the rear wheel-well??? in a little compartment.

Origami-engineering's .. simultaneously incredible & stupidly-frustrating )

I've held for years that they should be doing it to keep the starter-battery trickle-charging, but .. why make the customers have fewer costly/frustrating problems?

While that might not be economically feasible, I've always wondered why plug-in electrics couldn't send power back into the grid. No solar? Send energy onto the grid during the day from the car and recharge during the off-hours at night. Solar? Recharge during the day and send energy onto the grid at night. Just make sure to set a minimum charge that will get you to a charging station.