There is a small wind farm close to us. Driving back from shopping this morning, I noticed that 4 of the approx 14 there weren't turning and wondered why?
We have a wind farm near us but rarely are they all turning, I think that some are serviced while stationary or maybe if there is a good wind, only a few are are required but with little wind more are required to cope with demand, just guessing.
More seriously, demand in the daytime (and on a weekend) is not that high - where would they store the electricity produced? So they get turned off and switched on when required.