(this is one reason why the amount of storage required for an all solar/wind grid is usually vastly overestimated).
If you look at graphs of the wind and solar production in winter vs summer, the correlation is obvious. On a day-to-day basis, much less so, but on average low wind does tend to come along with higher sun.
This only happens in the designed operating window ( too light you get nothing, too strong you need to shut down ).
So one question is what window have your tuned your farm for?
Air density matters as well - the denser the more power - ie the colder the more power.....
So whether it's anti-correlated might a local feature depending on the local factors driving the weather?
Perhaps stronger correlation would be that air movement ( wind ) is the thing that drives the weather changing. ie no wind, means slow change ( though the opposite isn't necessarily true - if you are in the centre of a cyclic weather system which isn't moving you could have wind and not much change ).