Re: Fag packet calculation time...
That Leaf has a 40kWh battery. To charge that from solar panels in 3-4 hours means you have... what? 10KW of solar panels on your roof? Let's say on average it requires a half-charge, that's 5KW of panels at full whack for 4 hours, using 35+ square metres of solar panel.
Truth is, you're topping up the battery at best. Serious usage of the vehicle (150 mile range? That's a single 75-mile back and forth) would drain your proposed house battery and the entire daily solar output with less than one full charge. And you're doing that using a set of solar panels costing as much as the car (not including fitting and legal agreements on who owns the roof if you sell the house, etc.). And you're doing that on a roof which isn't available to most people.
Sure, you can do this. But stating it as if everyone can just do it, or would do it, is slightly dishonest. In actual fact any two-car families wouldn't have the roof-space. Anyone renting wouldn't be allowed to. Anyone in a flat wouldn't be able to. Anyone whose car is parked away from their house (even out-front in private parking) wouldn't be able to.
And each car requires 30-something square metres of solar to make it happen, at best, so local solar for those use cases - even if supplied by a town council, etc. as a solar-powered charging point - is actually sucking up land quicker than houses themselves are being built.
Fact is, if you want to have electric cars, you need investment in the electric network. YOU have invested £10k+ in your electric setup, which benefits just you, and supports one vehicle. To scale that up to millions of cars means the OP is right... lots of new nuke stations or entire counties full of panels, or forget it.