It seems like even a small solar panel on the roof of an electric car would make a lot of sense. When you’re sitting at work for 8 hours, your car can just soak up some sun. I’m assuming there is some sort of problem related to cost, rather than efficiency, but I can’t figure it out.
Edit: Thanks for the help. It makes a lot of sense now. I appreciate the in-depth answers too.
In: Engineering
It adds weight for minimal charging capability
A Tesla Model S is 5 meters long and 2 meters wide giving you 10 m^2 of area to work with. Best case you’ll get about 300 watts/m^2 in really good conditions so you can get about 3 kW from the solar panels on the car which can recharge that 90 kWh battery by about 3% per hour
But this assume covering the *entire* foot print of the car with solar panels in optimal conditions. Realistically you’re looking at 4 m^2 on the roof and less than 200 W/m^2 or about 800 W which recharges that 90 kWh battery at about 0.9% per hour.
The additional weight of the solar panels will burn through additional power every time the car goes to accelerate, and the added cost/complexity will make the car notably more expensive.
Solar panels and electric vehicles make a better combinations when you put them on an overhead structure with far more area that gets to stay in a single place
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