Planning · Key Metric · Yield Indicator

Full-Load Hours (FLH) for Wind Turbines

Full-load hours are the central yield metric: notionally the hours per year in which the turbine would have to operate at rated power to achieve its actual annual energy output. They condense wind resource, turbine type and availability into a single figure.

Definition

FLH = Annual yield [MWh] / Rated power [MW]

Example: a 6 MW turbine with 18,000 MWh annual yield → 3,000 FLH/yr. The year has 8,760 h, so the turbine notionally operates at (3,000/8,760) = 34% of the time at full load. The capacity factor is therefore 34%.

Typical FLH in Germany

Site type	FLH/yr	Remarks
Top coastal (SH, MV coast)	3,500–4,200	near-offshore conditions
Northern Germany inland	2,800–3,500	standard values for modern 6 MW turbines
Northern German uplands	2,500–3,000	NRW, Hessen ridgelines
Southern Germany inland	2,100–2,700	low-wind turbine standard
Southern German uplands	2,000–2,500	BW, BY exposed sites
Southern Germany lowlands	1,700–2,100	critical economics
Offshore North/Baltic Sea	4,000–4,800	typically significantly higher than onshore

What Influences FLH?

Mean wind speed at hub height: main factor (~70% of variation)
Turbine-specific power rating (W/m²): lower W/m² → more FLH, less absolute yield
Technical availability: 97% standard, 95%–99% achievable
Wake losses within the wind farm: 5–10% reduction in dense configurations
Noise-reduced night operation: −1 to −4% p.a.
Bat/shadow flicker curtailment: −1 to −3% p.a.
Ice accretion shutdowns: −1 to −5% p.a. (region-dependent)
Grid-related curtailment (negative electricity prices, congestion management): variable, 0–3%

FLH and Economic Viability

FLH	Typical LCOE	Economic viability
4,000+	40–55 EUR/MWh	highly economic, PPA-eligible
3,000–4,000	55–70 EUR/MWh	EEG standard
2,500–3,000	65–80 EUR/MWh	EEG auction economically viable
2,000–2,500	75–95 EUR/MWh	low-wind turbine, EEG south bonus required
< 2,000	> 95 EUR/MWh	critical — community wind model or self-supply only

Repowering leap: Old 1.5 MW turbines typically achieve 1,800–2,200 FLH; modern 6 MW low-wind turbines at the same site reach 2,800–3,200 FLH — a factor of 1.5×. This explains the large repowering yield multiplier beyond the pure capacity increase.

Full-load hours (FLH) wind energy by region in Germany: top coastal 3,500–4,200 FLH, northern Germany 2,800–3,500, southern Germany 1,700–2,700, offshore 4,000–4,800. FLH-to-LCOE correlation and repowering leap 1,800 to 3,200 FLH (factor 1.5x)

Full-load hours by region — FLH-economics correlation and the repowering leap

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Frequently Asked Questions

What are P50, P75, P90?

Probability quantiles: P50 = the median yield forecast (50% probability of being achieved). P75 = achieved with 75% probability (somewhat lower). P90 = very conservative (90% probability), used for bank financing.

Will FLH remain constant over the turbine lifetime?

No — typically a slight performance degradation of 0.3–0.8% p.a. due to wear and efficiency decline. Over 20 years this accumulates to 6–15% yield loss. Accounted for in modern yield models.

How do wake losses manifest in practice?

A turbine in the second row of a 5×5 wind farm typically loses 5–15% yield due to upstream-turbine wakes. Layout optimisation can reduce this to 3–8% — see the Turbulence Indicator (DE).