Wind Turbine Shadow Flicker

January 28, 2012

What is a Wind Turbine Shadow Flicker?

A wind turbine shadow flicker is a moving shadow casted by the blades of a wind turbine from the sun.  A wind turbine does not cast a shadow flicker during the nighttime or when the blades are not moving.  The length and direction of a shadow flicker depends on the location of the sun, wind direction, and the spatial relationship between the wind turbine and the receptor.

The effect of a shadow flicker is an alternating change in light intensity.  The effect could loosely be explained as mimicking the effect of a strobe light.

A shadow flicker will reach its greatest lengths during sunrise and sunset, or whenever the sun is close to the horizon.  If the sun is in-line with the rotor blades, the shadow will be very narrow and of a lower intensity.

Are Shadow Flickers Hazardous?

Yes, shadow flickers from a wind turbine can be hazardous to one’s health.  A shadow flicker, although rare, can cause photosensitive epilepsy or motion sickness for people who suffer from vertigo.  A shadow flicker can also simply be a nuisance to homeowners near a wind turbine, causing psychological stress.

Many residents who live within the reachable distance of a shadow flicker from a wind turbine consider the shadow very distracting and disturbing.