What is shadow flicker?
A. When the sun is shining, all objects create a shadow, and if the object causing the shadow is moving, then the shadow moves also. Shadow flicker is caused by the rotating wind turbine blades creating a rotating shadow, when the sun is shining, which falls across a narrow window into a building. When this is the case, it could be a nuisance. To prevent this potential problem the path of the sun can be mathematically calculated and can be modelled in a computer program. We then avoid siting turbines where they will cause problems OR If we calculate that unwanted shadow flicker may occur at certain locations at certain times, we can control the turbine to make it shut down for a few minutes at these particular moments in the year.
A. Shadow flicker occurs in very particular conditions when the sun is low in the sky and shines on a building from behind a turbine’s rotor. This can cause a shadow from the turbines blades to be cast on the building appearing to flick on and off as they rotate. When this flicker is viewed through a narrow opening it is known as shadow flicker. The potential for shadow flicker can be assessed for individual buildings around proposed sites. At a distance of 10 rotor diameters shadow flicker is unlikely due to the shadows intensity falling as the separation distance increases.
When the sun is shining, all objects create a shadow, and if the object causing the shadow is moving, then the shadow moves also. Shadow flicker is caused by the rotating wind turbine blades creating a rotating shadow, when the sun is shining, which falls across a narrow window into a building. When this is the case, it could be a nuisance. To prevent this potential problem the path of the sun can be mathematically calculated and can be modelled in a computer program. We then avoid siting turbines where they will cause problems. Alternatively, if we calculate that unwanted shadow flicker may occur at certain locations at certain times, we can control the turbine to make it shut down for a few minutes at these particular moments in the year.
