The key thing is, we need a better grid in Europe. While we do have a better grid than the US, simply measured by checking outage rates, it is nowhere near large enough to allow large scale transfer of power across the continent.

Assuming we had a decently sized cross-continental grid, it would be possible to have a lot of overcapacity in wind farms pretty much anywhere on the European coast lines - particularly in Portugal [1] and other areas with constant, strong wind power - and then transferring it to countries which do not have enough wind power.

Additionally, we could transform our industry, particularly aluminium smelters (for example, in Germany one percent of the entire power usage of the country goes to just two huge plants in Essen and Hamburg [2]) to seasonal production - basically, they would only be allowed to produce during the summer when there is enough solar power available. This will be expensive, yes, but unlike the sparsely settled US Europe simply has nowhere to store the waste of nuclear energy.

[1] https://www.evwind.es/2020/02/19/wind-energy-in-portugal-alr...

[2] https://www.handelsblatt.com/technik/das-technologie-update/...