[elihu]

Kind of a tangent regarding solar-powered cars:

Putting solar panels on a car is a good idea that sounds like a dumb idea that sounds like a good idea.

Solar panels don't actually generate anywhere near enough power to supply a car continuously. (1 horse power is about 700 watts. If it takes 10 HP to maintain highway speeds, that's about 7000 watts, more than most rooftop solar installations.) So, driving forever on a sunny day without stopping isn't something that's attainable except on specially-built cars with tiny motors and giant bodies and don't move at highway speed.

However, if I think about how I use my own car on a typical day, I drive a couple miles to work, park in the sun for about 8 hours, and then drive a couple miles home. Maybe stop on the way for groceries. If I had an electric car with a solar panel generating a hundred watts or so while it sits in the parking lot, that might be enough to keep the battery topped off.

I'd still have to plug in once in awhile if I drive around more than average or if I'm going on a long trip, but if it noticeably reduces the number of times I plug in per year, that's probably worth the added weight and cost.

(I realize that by "solar powered" you probably meant rooftop solar and charging at home or perhaps utility-scale solar.)

(I also realize that I could just ride a bike, but I'm lazy and technological cost-benefit analyses are more fun.)

[jdcarr]

I've always enjoyed the alternate idea of parking areas having shelters covered in solar panels.

Has the nice advantages of keeping your car cool in the summer and removing another piece of complexity in your car.

You could also set up the charge stations such that they either draw from the solar panels or from an alternate power source in the winter when there isn't enough sun to keep a really simple solution.

[epistasis]

I'd be surprised if you could get a full kWh per day out of solar panels on a car itself; they're at a non-ideal angle, can be parked in half sun half shade, etc.

Most cars get really close to 3.3 mi/kWh. So unless your commute is really short, it's not going to make a huge impact on the number of times you need to plug in.

[elihu]

My commute is really short. I don't drive long distances very often, so I think it would make a difference.

Another way to look at it is if I could get one extra kWh per day from solar and can go 3.3 miles per kWh, that's about 100 extra miles of range per month. I typically drive maybe 200 or 300 miles per month, so that's a pretty big reduction in total plug-in power that I would need. (In our Oregon winters it might not help so much, or if I can't reliably find sunny parking spots.)

[zumu]

> I'd be surprised if you could get a full kWh per day out of solar panels on a car itself

Is this assuming the car is parked outside the entire day or just the 8 hour work day?

[mandude]

Exactly! I said the exact same thing not long ago and it's a spot on assessment!