

From historical data, you can calculate the maximum lull where neither are providing enough.
The difficulty there is that there are a lot of places where you frequently get multiple weeks of both solar and wind at <10% capacity (google for dunkelflaute) that would need an implausible amount of storage to cover.
The OP article is already talking about 5x overbuilding solar with 17h of storage to get to 97% in the most favourable conditions possible. I dont see how you can get to an acceptably stable grif in most places without dispatchable power.
Yes, but the tricky thing is we have no idea when the seemingly exponential growth will flip over into the plateuing phase. We could be there already or it could be another 30 years.
For comparison Moores law is almost certainly a sigmoid too, but weve been seeing exponential growth for 50 years now.