One of the stranger accusations sometimes leveled at wind projects is that the flickering shadows from wind turbines' rotating blades can trigger seizures in epileptic individuals. Here and here are useful resources that refute this myth.
More generally, shadow flicker is a very well-known phenomenon that occurs seasonally when the sun is very low in the sky (casting longer shadows). Determining the number of hours in a year that a property neighboring a wind farm will experience flicker, and exactly where, is a straightforward calculation. Noble Environmental Power, a wind developer, has developed an excellent fact sheet on shadow flicker. Here is what it says on epilepsy:
Is there a connection between shadow flicker and epilepsy?
No. Shadow flicker from wind turbines cannot trigger epileptic seizures in individuals suffering from photosensitivity, as some opponents have claimed. The frequency, or the number of times something happens per second, is measured in Hertz (Hz). Shadow flicker from wind turbines has a frequency between 0.5 Hz and 1.25 Hz, which is equivalent to between 1 to approximately 1.25 alternations per second. This is well below the range of frequencies that can trigger epileptic seizures, which is 5 to 30 Hz, according to the American Epilepsy Foundation. Thus, shadowing from wind turbines poses absolutely no threat to the health of people with epilepsy or other individuals who are photosensitive.