That was exactly my point, you do not need a global grid for this to work a continent sized one already does a great job. That was why I used the EU as an example. As for seasonal storage the worst month last year had 42.8% renewables, which was March, the best was February so a month earlier with 60.0%. The average was 49.7%. So we are talking 20% up or down. That is also true when you just look at wind and solar. Average was 47.15GWh and the worst month was 40.97GWh and the best 59.00GWh. So again fairly even distribution over the entire year. So no need for seasonal storage, unless you have something super cheap.

That is real world data and not some crazy stuff. You basicly just have to overbuilt by 50% and add a days worth of storage to the EU grid to work and the ability to move around electricity.

Also I am talking about hydro power, which per wiki only makes up 16% of global generation. That has storage capabilities built in current reservoir power plants. en.wikipedia.org/wiki/Hydroelectricity#Properties