Why Do Some Wind Turbines Stand Still?
In short: A standstill usually does not mean "broken", but a controlled shutdown — due to shadow flicker, species protection, grid congestion, maintenance or negative electricity prices. In total, a turbine often stands still for several hundred hours a year, most of them as planned.
The 7 Most Common Reasons
- Shadow-flicker shutdown: When the rotor shadow hits a residential building within the minutes capped by the LAI (German states' working group on emission control), the turbine shuts down automatically — typically a few minutes on a few days per year.
- Species-protection shutdown: in case of collision risk (raptors, bats) or phenologically (harvest/mowing) — see Bird Strike and § 45b BNatSchG (Federal Nature Conservation Act).
- Grid curtailment / redispatch: When regional grid capacity is insufficient, the turbine is curtailed or switched off by the grid operator. The operator receives a compensation payment.
- Negative electricity prices: With very high renewable generation and low demand, exchange prices fall into negative territory — turbine operators then voluntarily switch off so as not to give electricity away (or, since the EEG adjustment, to avoid having to pay for it).
- Scheduled maintenance: service appointments, inspections, filter changes — several days of standstill per turbine each year.
- Storm control / storm shutdown: in extreme winds — see Wind Turbine in a Storm.
- Ice-build-up shutdown: sensors detect ice forming on the rotor blades and stop the turbine to protect against ice throw — see Ice Throw Hazard.
How Much Does This Cost the Turbine Operator?
| Shutdown reason | Yield loss (typical) |
|---|---|
| Shadow flicker | < 1 % |
| Species protection | 1–5 % (higher at conflict sites) |
| Grid curtailment (redispatch) | regionally up to double digits, with compensation payment |
| Maintenance | 1–2 % (technical availability ≥ 98 %) |
| Storm / ice | small — seasonal |
| Negative electricity prices | rising with renewable share, single-digit percent |
Overall, the technical availability of modern turbines is typically ≥ 98 %. The losses from regulatory and market-driven shutdowns come on top of that.
Frequently Asked Questions
Are turbines shut down for purely political reasons?
No. Shutdowns are based on permitting conditions, grid requirements or market-price signals. Political decisions act through the framework conditions (EEG, land-use planning), not directly on operation.
Does the operator receive money for every shutdown?
Only for regulatory-triggered grid curtailments (§ 13 EnWG (Energy Industry Act) / EEG). Not for permitting shutdowns (shadow, species protection) or for voluntary shutdowns due to market price.
Why do several turbines in a wind farm often stand still at the same time?
Because they share the same regulatory trigger (grid congestion, storm, regional electricity price) — or because maintenance in the farm is bundled together.
Reasons a wind turbine stands still – 7 causes with yield loss and availability