memes

While grid interconnections help, there is still a problem of weather not drastically changing at country boundaries. So for example Europe currently looks like this:

and has looked pretty much the same since the start of the year.

So very little solar production is going on anywhere, that leaves wind as the only active intermittance source, so places that have a lot of wind production like UK and Denmark use all the wind they produce, and countries that make less power from wind and more from solar have nowhere to import significant amounts from.

You need either dispatchable power (gas/nuclear) or long term grid scale storage (multiple weeks worth) to make a power grid work. Currently the latter is prohibitavely expensive so the former is needed.