Honestly it seems like a no-brainer to me to put a solar panel on the roof of electric cars to increase their action radius, so I figured there’s probably one or more good reasons why they don’t.
Also, I acknowledge that a quick google could answer the question, but with the current state of google I don’t want to read AI bullshit. I want an actual answer, and I bet there will be some engineers eager to explain the issues.
A few of them have. The core issue is it doesn’t add much range, while at the same time adding more cost, weight, and complexity. On a sunny summer day you can expect to get single digit kilometers added to the range, while on a cloudy winter day you won’t get even a full kilometer added.
They do make some sense on hybrids, as they are lighter so the range increase is a bit more and people are less likely to charge a hybrid. But, they still suffer from not adding much range, while adding cost, weight, and complexity.
Bear in mind also that the extra weight and possibly aerodynamic compromises actually reduce range. In some cases, particularly at night, in poor weather, and at high speed, the panels would be a net negative.
They would only be useful if your car sat around in the sun for long periods without access to a charger.
such as parked at work or in a summer traffic jam?
Parked at work it will probably have a building nearby that creates a shadow. In a traffic jam, assuming perfect sun conditions and no shade, a 100W panel will generate around about 500m (or yards) of range per hour. Meanwhile the AC will use about 700W to 1kW of power to prevent your face from melting.
Some tests on YouTube report a realistic addition of 1 mile per day using the car in a typical commute.
Depending on the car and the temperature, AC Is simply not an option (same for heat) in a traffic jam. I drove a 2019 Nissan Leaf (with 12/12 battery bars and normally 80-140 miles in range, depending on the season)for my 19 mile commute for a while, and had an awful time during subzero temperatures (~-20 Celsius) once. I went from fully charged on the work chargers to considering breaking out my reflective emergency blanket in three hour stop-and-go traffic so as not to kill my battery before home. I stopped to charge and it took much longer than usual, to the point that I just gave up and used my hand warmers and hoped on the way home.
I don’t blame the car for that, I was unprepared for the predictable consequences of cold temperatures on electric cars, but it was still super unpleasant.
Leafs have battery packs with no active heating or cooling, which significantly impacts their performance in bad weather and when fast charging. Coupled with very small packs in the early models, and you have a recipe for a bad experience.
You’re better off putting the panel somewhere where it always gets sun, and isn’t extra weight you have to haul around.