I have occasion to drive by many modern windmills (the three bladed tall towers) but I note that many are not spinning. This is not due to lack of wind (some are spinning and I know the wind is blowing).
I get some will be broken/need maintenance but, unless these things are super unreliable (which I doubt), most should be able to spin and generate power.
My guess is there is too much power on the grid so they are not needed but does that mean they get paid to NOT generate power?
Anecdotal but ISTM I see them idle more than spinning.
Even a slight instability will cause large horizontal axis wind turbines to experience adverse and potentially destructive dynamic loads. They are designed to go into a ‘failsafe’ mode if they detect unbalanced loads or excessive vibrations. They’re actually pretty difficult to maintain, especially if there is damage to a blade, and replacing a blade, gear box, or generator is a major operation requiring a large crane and experienced team that can only work under light wind conditions. Windfarm operators have been desperately looking for experienced technicians and will pay a premium, which is good work if you don’t mind constant travel, working at heights in windy conditions, and being constantly overworked due to lack of staff.
Wind turbines are one of those things that look good on paper—relatively cheap to install and operate, a theoretically good ROI, and don’t produce any waste or pollution in operation—but are a lot more complicated in operation. Although it is sometimes claimed that they are energy negative in total lifetime costs that just isn’t true, but getting anything near optimal performance is difficult notwithstanding the load balancing problems of wind power in general which makes them only suitable for a small fraction of overall power demand.
We have windmills near here that have been inoperable for many years (at least eight) due to lawsuits from people more than 1000m away, saying that the sound and shadows cause some kind of mental harm to them.
In addition to planned and unplanned maintenance, turbine blades can be parked when there’s insufficient demand for energy. Some areas of the country (California) are building out battery storage facilities, but not all areas have that. Hydrogen storage is another possible solution.