Let's see. Capacity of a Tesla battery: 85kWh. Let's say 1m^2 of solar panel can produce 200W in good sunlight, and we'll handwave away all other conversion inefficiencies. Let's say we get 8 hours of good sunlight a day, so in a day 1m^2 of solar panel will give 1.6kWh. So with 54m^2 of solar panel, we can get 1 Tesla charge in a day. Maybe that could work outside of a city where everyone has a big backyard, or can cover the roof in solar panels, or both (I don't think my roof is anywhere near that big at least on its south-facing side, and the back is in shade). Maybe you can buffer it in a vanadium-redox battery so you can actually charge the car overnight. But with the cost and the amount of solar you need if you can only get 100W/m^2 for 4 hours a day, that's going to get real big and hence expensive. And that's when you will really need the vehicle because maybe the weather is too bad for alternatives.
Electric cars in cities are going to go on being powered by a central grid forever, basically, because physics.
You are correct that there's still a need for a grid. But that grid can be cleaner and more efficient with renewables and energy storage that gives everyone similar benefits to solar panels on their roof.
"California is the only state with extensive deployment of wind, solar, and geothermal energy. California's venture capital investments in sustainable energy are greater than the other 49 states combined, at $2.2 billion in 2012. In August 2018, California's legislature passed legislation that mandates completely carbon-free electricity generation by 2045."
This is the same idea as you don't use up a full tank of gas on most days.