Yes, it is possible and I am considering if this would be worthwhile to do. Why would people put solar panels on vehicles?
There are a variety of reasons why people would put solar panels on vehicles. The first one might be to keep a trickle charge going to the battery. Not everyone uses their car each day, and some people like farmers might have an old truck or vehicle that gets used rarely. They need a way to keep the battery from fully discharging, so a small solar panel connected to the battery can keep enough charge in the battery so that it doesn’t die. These systems are pretty cheap and generally less than $50. As a side note, many solar generators have alligator clips that can connect to a battery and jump-start a dead battery.
Another reason solar panels on vehicles make sense is RVs. Those are used to live in and solar power can reduce the burden on the need to charge the RV batteries from RV parks, or the onboard generator. I have watched lots of RV videos where people who used to use their generators to charge their batteries no longer need to do this because of their solar panels. This means they don’t need to spend money on fuel, and also don’t pollute in the way they were before. This electricity can also be used for AC/heat so it further reduces their dependence on things like coal, propane, or diesel fuel. For RV’s who like to “boondock” Solar panels let them be almost self-sufficient. They only need to gather water to be off-grid completely.
Others have solar panels on a vehicle as a way to supplement their home energy solar panels. Since many cars are just sitting in a parking lot, by having a solar panel the car is doing something useful when it is off. They connect it to a solar generator and then can use that energy to add to their home system easily with a connecting wire. Or that energy is useful if they have an emergency and have to pump air into their tires, provide lighting at night if their car fails, or use tools if they are workmen. For rural farmers or construction, having the ability to have mobile power is very useful in their lives.
Many people are able to do this themselves or pay someone to do it for them. To me, this is a worthwhile thing to do. I haven’t done it yet because I am still working on my home system but once this is done, then I will explore solar panels on my SUV. It will be fun to maximize the benefits of the sun.