Comment by bruce511
3 hours ago
Solar power on the roof of an EV car seems like an obvious play. And yes some energy can be derived this way. But it's important to understand the limitations of physics.
When the sun is directly overhead we get about 1kw per square metre. Very good panel effeciency is about 25%. ) I'm rounding a bit to make math easier.) The average car footprint is maybe 6 square meters. Obviously a lot of that is curved away from the sun, or is glass. 4 square meters here is perhaps a reasonable starting point.
Which means if we plaster the car with solar cells, we might get 1kw of output in pretty optimal conditions. Perhaps 12 hours of generation depending on latitude, time of year, and so on.
Most EV cars have 30 to 80 kw batteries (some more). So 12kw of charge per day is not nothing, but also not enough. Given pesky things like shade (from tall builings or trees), undercover parking, clouds and so on, daily average is much lower.
Solar film in general is great. But current pricing makes it cheaper to just install regular solar panels in most places. Less portable maybe, but more (financially) efficient to generate/store/charge as we currently do.
On the other hand the aesthetic of a solar panel car roof is very cool, and maybe covers the aircon power requirements on a hot day.
A solar panel would obviously not cover the usagebof a consumer car while it is being driven.
Consumer cars spend most of their time not being driven. If someone commutes 10 miles to work each day, they would nearly never need to charge the car.
Right, but for a fan, it would work. Cars heat up mostly in direct sunlight. The solar panel could be wired directly to a fan. This would also prevent heat death of dogs and forgotten children.