> It doesn't get around the fact that it still makes way more sense to put those panels on your house roof and charge from that.

On a car it also acts as a range extender and emergency backup (if you're out of battery and the car is engineered for, you can crawl along at the charge rate or wait a bit for a better charge). It's not great, but being to "walk" with your car might save your ass.

And if the car is designed around this idea (à la lightyear one), you can increase things further (the LY1 folks advertise a solar charge rate of up to 7.5mi/h WLTP with no A/C).

If solar panels are the bottleneck then they shouldn't be wasted on people's rooves, either. They should put them in a big field where the electricity company can point them in the optimal direction, perhaps with a device to redirect them during the day, or mirrors, and look after them properly: clean them, if that helps, or whatever.

Tracking and concentration is not cost effective, so it’s just a tilt advantage.

Solar panels in a remote location need to be converted from DC to AC for transmission, then transmitted long distances with associated losses, then converted to DC again to charge the car, stored in batteries in the car with associated losses. A solar roof could actually be a net gain assuming the energy is used while the car is in motion, and it’s used near the equator so no tilt required.

That is an excellent point - if you have a house. It might make more sense for people who have to live with streetside parking?

Why not do both?

Because resources are scarce. If solar panels were free, then yeah let's plaster them everywhere. But let's start with where they make the most difference.

Because very few people have covered every last spot on their roof so you would be designing a product suitable for very few people

Or for people who don't own a roof at all - plenty of such people in cities.

Those people also have their cars in multi level car parks with no sun so that doesn't work for them either. In that case they would be better having the car park have solar and the local government building solar farms. A panel on something almost always undercover makes no sense.

I live in an average residential street in Europe full of 3 story residential houses. Our house with 6 apartments has 3 garages, the majority park on the street.

Sure, the government or the electricity company could just install car chargers and put a solar plant to power that in some rural area. But if I want something now then buying a car is much simpler than lobbying for that.

Very few people have electric cars to begin with, and they're really expensive compared to ICE vehicles so you're already talking about a demographic that's demonstrated a willingness to pay a premium for driving an electric car.

If Tesla offered a "Solar Panel Kit" that made their cars even a few percent more efficient it would sell like hot cakes.

And on every parking lots...