You can't run a turbine 24/7 either, they require maintenance windows.

Yes, you can run a turbine 24/7, just not 365 days a year.

For gas turbines, n+1 is probably good enough for up to n=10, then n+2 and so on.

If one breaks down or is undergoing maintenance you have a spare.

Solar can’t work like this. Even if you build 2n solar capacity, you still have a not insignificant fraction of each day with no power.

Meanwhile a gas turbine can be running continuously for week to months between service intervals.

Just add batteries? Ok, but that’s no longer solar, and comes with not insignificant additional costs and maintenance etc.