To me it comes down to the
To me it comes down to the practicality and cost of car-solar panels.
There is only a certain amount of space on a car where you can mount solar panels, and the cost and efficiency are two other limiting factors. On the good side, an EV has batteries to store electricity and an inverter, so with much of the necessary equipment to make it work, it doesn't seem like a bad idea. But if you are looking adding say 400kW per hour in direct sunlight, and the addition of the on-board system may add as much as $2000 to the cost of the car, it's a harder decision to justify. If you have a home where you can install fixed solar panels Tesla is offering a 3.8kWh solar installation for $45 a month ($65 in CA) that produces 13-16kWh per day. My PHEV uses 12.5kW for 45 EV miles of driving, or about 3.3 cents a mile, which is a far better solar value. Now back to the Bolt. GM could certainly build in a solar panel to the roof and hood of the car, especially the larger upcoming EUV. But would the package be worth it for the price? Both Toyota and Hyundai offered models with built in solar panels, but the power yield and cost didn't provide sizable power gains or a good value. The prototype Prius shows a real gain in usable range with new high yield panels, but it does appear to have panels covering the back window. Like many innovative ideas, it is interesting. But the real world value of built-in automotive solar panels doesn't appear to be great just yet. Especially compared to home solar (where possible). So this is still a wait and see technology for me until a breakthrough in price/value happens.