Depends on whether they go to zero, or just drop to 50% of normal output. If it's the latter, then it might be cheaper to build twice as much wind as you'd nee

Depends on whether they go to zero, or just drop to 50% of normal output. If it's the latter, then it might be cheaper to build twice as much wind as you'd need at optimal times than to build a nuclear plant. You'd need to do the maths for the specific situation. (And also if they drop to 0% for an occasional hour then you can use batteries. If once every five years they drop to 0% for two weeks then you absolutely need to have something else that can fill that gap.)