Comment by pfdietz
With proper system design this becomes a non-problem. This adds cost, but done properly it's cheaper than a system based on nuclear, especially going forward as renewable and storage costs continue their relentless decline (at a pace nuclear could only dream of).
In more detail: you want two kinds of storage, one optimized for daily charge discharge, and one for long term storage, to handle different frequencies in the power spectrum of the power-demand mismatch curve. The first is batteries, and the second is various techologies (like thermal or hydrogen) that will be brought into play for the last 5% or so of grid decarbonization.
And we do have detailed weather data for the last 70 years in Europe.
So it should be easy for proponents of renewables plus batteries like you to show that their proposed solutions would have worked all those years.