Wind turbines that “rest” at the right moment can gain ten extra years of life, but only if they rest for the right reason
Across parts of Europe, electricity prices occasionally turn negative — meaning the grid is so flooded with power that producers effectively pay to keep generating. For offshore wind farm operators, the response seems obvious: shut the turbines down and wait it out.
But a new study suggests that decision is far from simple. Researchers who simulated the Lillgrund offshore wind farm hour by hour found that the consequences of a shutdown depend critically on one factor operators rarely track — whether the surplus electricity is coming from wind or from solar. That single distinction, the study finds, can mean the difference between ten extra years of turbine life and just one.
When electricity Prices go negative
Negative electricity prices are no longer rare anomalies. As Europe has added renewable capacity at pace, grid oversupply has become a recurring feature of wholesale power markets. When more electricity floods the system than demand can absorb, prices fall below zero — meaning generators must effectively pay to keep producing.
Under wind-driven negative prices, the hours when the grid is oversupplied are also the windiest hours — exactly when turbines accumulate the most mechanical stress.
The trigger matters enormously. Wind blows at all hours; solar peaks midday. Prices go negative when either source surges past grid needs, and that timing difference shapes everything for an operator deciding whether to curtail.
When prices turn negative, curtailment is the rational response. The question the study raises — largely ignored by the industry — is whether the source of that oversupply changes the value of that decision. It does. Dramatically.
A simulated wind farm put to the test
To find out how much the price driver matters, researchers modeled the Lillgrund offshore wind farm hour by hour across three constructed price futures. Each future contained the same share of negative-price hours; what differed was the cause. One future was driven by wind overproduction, one by solar, and one by a combination of both.
The same operating rule applied across all three scenarios: whenever projected farm revenue fell below a set threshold, all turbines stopped. That threshold was varied systematically to test sensitivity to the exact cutoff. The model integrated turbine control, fatigue load accumulation, contract settlement, project financing, and carbon accounting — letting researchers trace the full downstream consequences of each shutdown decision.
The lifespan gap: Ten years versus one
Under wind-driven negative prices, the hours when the grid is oversupplied are also the windiest hours — exactly when turbines accumulate the most mechanical stress. Curtailment removes those high-stress hours, stretching the fatigue budget much further. The result is a potential lifetime extension of roughly ten years per turbine.
Under solar-driven negative prices, the picture differs completely. Negative-price hours coincide with midday solar peaks, not wind peaks. Curtailed hours carry only average wind speeds and ordinary fatigue loads, yielding a lifetime extension of about one year.
That gap translates into several million euros of additional value per farm across every scenario modeled. The turbines are the same. The operating rule is the same. Only the source of the surplus changes the outcome.
Carbon Accounting Turns in Opposite Directions
The environmental consequences split just as sharply. Under wind-driven negative prices, curtailment actually improves the farm’s carbon performance: net displacement of carbon emissions rises by about 17%, because the removed hours are ones where additional wind generation would have displaced little extra fossil fuel anyway.
Under solar-driven negative prices, the opposite occurs — curtailment marginally reduces the farm’s green contribution. This complicates a common assumption that curtailment is environmentally neutral. Whether a wind farm aids or slightly hinders decarbonization during curtailed hours depends entirely on what’s causing the price signal in the first place.
Why Support Contracts Must Catch Up
The study compared four contract-for-difference designs, all requiring the same present-value support. A production-based contract — paying nothing on energy delivered at negative prices — saw its required strike price rise by roughly 40% under wind-driven futures, a significant cost increase for the support scheme.
Two capability-based contracts, which pay based on energy a farm could have delivered regardless of actual output, kept their strike prices near historical levels. Only one contract design fully preserves the operator’s incentive to curtail wisely: a contract settled on available energy at every price point, leaving fatigue and carbon benefits entirely in the operator’s hands.
What Comes Next
As solar capacity continues to expand across Europe, the balance between wind- and solar-driven negative prices will keep shifting. Grids that once saw oversupply mainly on windy nights will increasingly see it on sunny afternoons — changing the calculus of curtailment in ways current contracts and operating rules simply weren’t designed to handle.
The study points toward a clear need: price-driver awareness built into both turbine control systems and contract design. Regulators and developers who treat negative prices as a single undifferentiated problem risk leaving years of turbine life — and millions in value — on the table. Knowing why the price went negative may soon matter as much as knowing that it did.
Reference: Gräfe, M., Kainz, S., Pettas, V., Ioannou, A., Kolios, A., Göçmen, T., Sandua-Fernández, I., Eguinoa, I., and Dimitrov, N.: Wind farm value, revenue-triggered curtailment and support-scheme design under wind- and solar-driven negative prices, Wind Energ. Sci. Discuss. [preprint], https://doi.org/10.5194/wes-2026-188, in review, 2026.
Daniel García is an Editor-in-Chief with strong expertise in structural work and engineering principles. He combines this technical foundation with deep knowledge of energy, spatial design, and emerging technologies, bringing a forward-thinking and analytical approach to editorial leadership.
