

It would be easy to find enough solar panels to charge an electric vehicle in most sunny areas, though it would probably be easier to just look for a large enough existing install and skip all the DIY. (Just look for the shiniest roof.)
But I think the real problem is in the EV itself. Batteries self-discharge and chemically degrade over time, so unless the apocalypse was recent, a lot of EVs you find might have damaged batteries, especially if fully discharged to begin with.
You could cannibalize one or more EVs to cobble together enough good cells to get past the safety cutoffs, but it would take a while and you would need to be careful since internal voltage in EVs tends to be high (like 400-800 volts).
TLDR: if this is a movie depiction, definitely use a montage.
Mad Max the musical now on Broadway