I regularly conduct Ag operations in amongst them while they are turning and I haven't experienced anything that I would describe as turbulence. The most dangerous part of any wind farm to a pilot is those wind monitoring towers that are always found nearby because they are so difficult to see. The NZ Ag. Association got all the ones in NZ made high vis under their OH&S laws, don't really understand the hold up in Australia for this to happen, considering the fatal accidents they have caused over seas.
On a personal note, the fact they require more 'dirty' energy to manufacture, than 'clean' energy that they will ever produce in their life, renders them kind of pointless to me.