The simplest answer is that it has been done, but adding solar panels to the roof of a car would add about 3 miles a day in ideal conditions.

I may be wrong but I don't think a solar panel that small could make a significant difference. 6 to 10 wats per SQ foot. To charge some vehicles takes about 7200 wats.

Solar panels cost money, require additional assembly costs and time, and add weight.

There’s new tech that addresses the second two to some degree, but being new, it brings more of the first.

[removed]

Some are,.. the Fisker Ocean has them. But they the amount of surface area generates so little power relative to needs of vehicle, especially since it’s often parked inside a garage, or night time, or cloudy. They cost a lot, would be expensive to repair if damaged.

The amount of charge you would get from a solar panel on the roof would be negligable. It would take days or weeks with good weather to get enough charge to get to the next charging station. And the weight of the solar panels and charger would reduce your overall milage.

Some years ago before electric vehicles became as common Nissan was pushed into this on their Leaf. They did the math and had worked out that it would not work but eventually gave in to public pressure. However they mounted a smaller solar panel and would only charge the 12V service battery, not the main battery. This did make some sense as it allowed them to stay parked for weeks and months without running out of charge on the service battery.

Solar panels don't really collect enough energy compared to what a normal car consumes to keep going.

In addition to that the panels will add cost and weight to he car. Under bad circumstances solar panel may actually decrease the range of a car rather thane extend it, because the car consumes more extra energy to carry the weight of the panels around than the panels give it.

There are some extreme cases like specially built racing cars that are ultra light and race through Australia with the power of the sun.

For normal cars that have things like safety features and amenities and drive though places that are not desert it would not work.

This is not an engineering problem that can be overcome with better technology, there simply isn't very much solar energy that hits a patch of earth the size of a car. and the minimal amount of energy to move something the car even with the most efficient engine is also fixed. Those are hard limits.

It makes much more sense to put some solar panel on the roof of your garage and charge the car while it is in there (potentially overnight with the help of a battery).

Another way to look at this is to look at nature.

Plants are solar powered and animals are powered by eating plant or each other.

Why doesn't a cow simply start doing photosynthesis so it has to eat less grass. Mostly because evolution does not work that way, but also because the amount of solar energy you can collect from the area of a cow hide is so much smaller than what you ca collect in a meadow full of grass.

There are some animals like sea slugs who do some photosynthesis but they don't need much energy because they don't move around much. A sea slug floating in the water needs less energy than a cow that keeps running around.

So you can totally power a car with solar energy alone, provided you either collect the solar energy outside the car and let it harvest it like a cow eating grass by plugging it in, or you can put the solar panels on the car but than you have to build it ultralight and only drive it in the desert, or you can build it like a normal car and put solar panels on it but simply not move it much at all.

Please read this entire message

Your submission has been removed for the following reason(s):

• ELI5 requires that you search the ELI5 subreddit for your topic before posting.

Please search before submitting.

This question has already been asked on ELI5 multiple times.

If you need help searching, please refer to the Wiki.

If you would like this removal reviewed, please read the detailed rules first. If you believe this was removed erroneously, please use this form and we will review your submission.

Please read this entire message

Your submission has been removed for the following reason(s):

• ELI5 requires that you search the ELI5 subreddit for your topic before posting. Users will often either find a thread that meets their needs or find that their question might qualify for an exception to rule 7. Please see this wiki entry for more details (Rule 7).

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.

It generally costs too much for any sort of additional utility it creates.

A quick calculation. An average EV would have about 50 Kwh battery, that is 50,000 Watt hours of battery. The average solar panel produces 200 Watts/m^2 and even optimistically, there wouldn't be more than 4 sq meters of space on a typical car for solar panels. So the panel would charge at 800 Watt hours per hour of charging. A typical solar panel parked in most places on a sunny day achieves about 4-5 hrs equivalent of "full sun". So this means around 4,000 Watt hours if the car is parked an entire day, charging. This is less than 10% of the battery capacity.

In practice (not so sunny days, parked in garage, temperature, shade etc) a solar panel mounted on car would be lucky to achieve even 25% of this. So this amounts to 2.5% charge on a typical car battery.

This is simply not worth the cost of the panels and electronics since just the additional weight of the panels and electronics probably increases the electrical usage by 1-2% (the car now has to carry the panels etc). So the net result is minimal and would just never justify the cost.

[removed]