Sweden and Norway are lucky to have long chain of mountains to run hydro. Scandinavian hydro won't power everybody's electric cars...
Nuclear is the only, well, nuclear solution
Nuclear also goes stale once in a while, when plants are taken offline for maintenance.
Solar is predictable, it generates in the day (when demand is highest), not at night. With connected vehicles you have massive battery banks of power that can be bought back from people, and as you've used the excess energy when you have been producing more than the demand from those resources to create green hydrogen, you reverse the process.
Same for solar. It's not predicatable on day-by-day bases.
With using cars as battery banks, even if you skip the problem of having cars connected all the time, you'll need to redo grid in a big way. Both to fill simultaneously cars if cheap solar energy hits the grid and keep the grid going on a stale cloudy day.
On the flip side when there's surplus that's used to make the hydrogen, to recharge the resovoirs, etc.
Many people feed back to the grid with their home solar etc, no difference to electric charging.
Not many cloudy days in the Moroccon deserts
The other issue is, how much grid upgrades do you need to allow to keep it up from electric cars? Maybe even on green front it'd be better to have stable power generation with simplified grid. All those beefy substations don't come out of thin air.
The EU currently learns every day that depending on unreliable countries is a bad idea for your energy needs. But I think we will still find solutions without involving unreliable partners by extending the cooperation within the EU.