Wind Energy Projects and Shadow Flicker

Shadow flicker is the effect of the sun (low on the horizon) shining through the rotating blades of a wind turbine, casting a moving shadow. It will be perceived as a “flicker” due to the rotating blades repeatedly casting the shadow. Although in many cases shadow flicker occurs only a few hours in a year, it can potentially create a nuisance for homeowners in close proximity to turbines.

Computer models can accurately predict when, where, and to what degree this problem will occur, so wind project developers can mitigate this impact during the site selection process. In addition, many local ordinances incorporate language addressing shadow flicker to minimize any potential impact on neighbors.

The impact of shadow flicker from small wind turbines is minimal due to shorter heights and smaller rotor diameters.

More Information

• In the Shadow of Wind Energy: Predicting Community Exposure and Annoyance to Wind Turbine Shadow Flicker in the United States
• OpenEI: Shadow Flicker