Can already do this on the Tesla. It’s not solar, but cracking the windows and running the fans to keep it vented isn’t going to burn more than a mile or two of range.
The best way to spend money improving an EV is almost always going to be on batteries or weight reduction. Self charging is neat, but unless you get much more efficient solar arrays, it’s always going to be limited to niche applications. Five miles more range is always going to be useful, solar arrays which add a mile or two of range under specific conditions are far less interesting.
I agree that in many cases an extra dollar of battery capacity provides more utility than an extra dollar of solar charging.
But I did have one of those niche applications a while ago: I used to travel for work and often left my car parked random airport lots for months at a time which meant I occasionally came back to melted cassette tapes and a dead battery. In that case $100 of solar panels to run an exhaust fan and/or trickle charge the battery seems like it would have provided more utility to me than $100 of additional battery capacity.
I wouldn't be willing to add thousands of dollars worth of solar panels like the Sion and even if I did I wouldn't consider it a replacement for charging via the electric grid. But if my next car comes with an optional/after-market "solar package" that can integrate solar panels into the roof that seems like it would provide some value to me, at least more than the fancy wheel or audio packages they currently offer.
This brings back memories of slowly dying car alarms back in the 90s.
I probably come across as being more anti-solar roof than I am. Mostly just feel like this isn’t a feature I’d make a purchase decision on and wouldn’t likely pay too much for.
I was reading on the Tesla forums about just bringing a portable solar array for camping and it’s weirdly a lot more complicated than you’d think. Perhaps having it integrated would make it simpler, but it’s a lot trickier than just topping off a 12v battery with a solar array.
Interesting, I hadn't know that about Teslas. On a Prius you can mount a ~$50 12V solar trickle charger on your dashboard, possibly with some rewiring [1] to keep one of your 12v sockets live, and it's even easier on older trucks. I'd imagine that the smarter the car, the harder it is to make those kinds of modifications. Even so, an optional "solar package" that integrates cleanly with the dashboard (or roof) seems like it might have broad appeal.
And if your only goal is to use it as an excuse to talk to your friends about having solar panels in your car then a small panel makes even more sense -- you can talk almost as much about a small panel as a large one for a fraction of the cost.
The best way to spend money improving an EV is almost always going to be on batteries or weight reduction. Self charging is neat, but unless you get much more efficient solar arrays, it’s always going to be limited to niche applications. Five miles more range is always going to be useful, solar arrays which add a mile or two of range under specific conditions are far less interesting.