Both nuclear & solar produce power at times when it's not wanted. Same defect.
If you were building a grid from scratch in a typical American region, and you were aiming for lowest cost, you'd overbuild solar enough that it handles 100% of demand on a sunny evening, add enough wind to handle 100% of demand on a dark + windy evening, then add about 3 days of battery storage. That'll supply you over 95% of your energy needs.
But that's not 95% of the power, it's 100% of the power 95% of the time. So you also need to supply 100% of the power 5% of the time somehow else. That's not 100% of peak, since peak is during air conditioning demand when solar works, but 100% of almost peak.
The cheapest way to do that is low efficiency single cycle natgas. CCS natgas is 1/20th the cost of nuclear, and single cycle is about half the cost of CCS.
So if you make 2.5% of that nuclear, you've doubled the cost. And you've saved a few hours worth of carbon emission, 2.5% of 5%.
If you want to be carbon-neutral, you use syngas instead of natgas. Yes, syngas is 6X as expensive, but fuel is not the main cost of a peaker plant running <= 5% of the time.