And throw overcapacity at the problem. If a bad day gives you 5% renewables with the current capacity then you "only" need 20x more capacity. Combining with other solutions this overcapacity factor goes down significantly.

And once you have intermittent excess energy that is essentially free some opportunities to use it might spring up, e.g. run various electrochemical processes for free and store the products or smelt aluminium or something like that.