– Why do electric cars not have solar panels on rooftop so they could be charged while driving/parked
In: Engineering
You have to drive everywhere with the weight of the solar cells, which is not insubstantial. Because cells are typically flat, they are also not shaped to provide great aerodynamics. This costs you for the materials, and measurable loss in driving efficiency.
Phoenix AZ (a **very** sunny place) averages 5.78 kilowatt hours of solar irradiance per square meter, per day. A typical car roof is 1.5 m^2, and affordable solar panels are about 20% efficient. That means, at best, you could generate 1.7kWh of power on a great day in a very sunny location.
A Tesla battery holds from 60kWh up. This means, for all that extra cost, and the losses from carrying the panels around, you might fill 1, 2 or 3% of the battery at the end of the day.
The bet is that the loss in driving efficiency and addition to the cost of the car, and that fact that the vast majority of people do no live in places like Phoenix, means it’s just not worth it.
Now, a tiny solar panel running nothing but a fan (no battery), would cost very little and may well save money on cooling. You would return to a cooler car that you did not need to run the air-conditioning as aggressively.
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