Whilst it is possible to predict periods when shadow flicker could theoretically occur using industry standard software packages, there are no guidelines in the United Kingdom to quantify what levels (if any) are acceptable.
What is shadow flicker?
Under certain conditions moving shadows cast by wind turbine blades can pass over windows in a building. To people within that building, those shadows can appear to flick on and off; this effect is known as ‘shadow flicker’. The moving shadows can also be seen passing across the ground, which can be considered as ‘shadow throw’.
TNEI’s shadow flicker services
- Carry out shadow flicker assessments for urban and rural wind energy sites
- Use industry standard software to assess shadow flicker potential
- Assess a range of sites from single turbine developments to multi-turbine wind farms
- Carry out assessments for developers and local planning authorities to minimise flicker through good site design without restricting site capacity
- Draft suitable planning conditions and protocols for sites where shadow flicker is anticipated to protect local residents against the impacts
- Provide technical mitigation measures and advice on appropriate planning conditions
- Provide detailed analysis of potential periods of downtime resulting from shadow flicker management, an essential tool for accurate project revenue calculations
- Undertake shadow flicker complaint investigations
- Use specialist software to identify which turbines are causing the shadow flicker
- Advise how shadow flicker impacts can be mitigated
- Deploy specialist monitoring equipment to measure the levels of shadow flicker at individual receptor locations and verify the success of any mitigation measures that are adopted.