Because they don’t generate enough power. You would have to leave your car out in the sun for a day in order to drive 10 miles.
There is one application where they do work, and I’ve seen them.
Golf “cars” used on military bases and industrial properties where maintenance people need to drive out a few miles at most, then park for a few hours while working on something.
The golf “car” is big enough to carry the tools, and the entire top is covered with a “surry” kind of roof from front to back that’s covered in panels.
It’s still probably cheaper just to run a gas engine, or return the golf “car” to a 12V charger, but I have seen these panel covered carts around.
LOL.
Had colleague who was an Eco nut in the 90’s.
Had a converted electric car powered by lead acid batteries.
The roof was covered with solar panels.
First the thing handled like a pig because of all the weight in the front from the mass of batteries. Second it would slow down as load increased, and going up a ramp with a low charge would slow it to a crawl. Third, we lived in Sacramento, and all it had was a tiny fan on the dash for cooling.
Dan would come to work drenched in sweat during the 100+ degree days in the summer. Best was one day, about 3 miles from work he ran out of charge and had to coast into a local gas station, and ran his 110 volt extension cord into the stations outside outlet and ran the 3 miles to work.
I can't stand the things, but for folks who live in populated areas, that's probably more than enough for their daily commute or trip to the grocery store and back.
I'll stick with the internal combustion engine for now.
Figure one acre of solar to equal 1 megawatt. From a wind perspective, that’s one windmill. For a coal or nuclear plant, it’s 800 - 2,000 megawatts per plant.