Balancing cost rose 16% in 2025/2026 to £3.1 billion, with a just under £0.5 billion of the total cost paid to wind farms to turn down.
Thermal constraints, those bottlenecks where power lines can’t safely transport any more power, remain the largest component. The costs of keeping voltage steady and responding quickly to changes in supply and demand also rose, as the needs of the electricity system continued to change.
NESO says it is taking more balancing actions to manage the electricity system, claiming for every unit of electricity the country uses, the operator is doing “more than twice” as much balancing than in 2018.
A report by NESO states that December 2025 had higher unconstrained wind (9.2 TWh vs 7.9 TWh) and higher wholesale power prices (£64/MWh vs £53/MWh).
However October had less network capacity available, which was 52% across the B4/B5 boundary in central Scotland, compared with 67% in December.
Many may question if less wind would solve the issue but NESO says without the renewable source, the country would need gas to replace it and more to replace the wind generation that isn’t constrained, which would add to costs.
There have been some calls for network reformation or a new network, which the operator says will take time and will still require more again in the future.
Gas is said to be the biggest part of the cost and the balancing costs to gas prices can be seen in recent months. The average cost of actions has grown from £90/MWh in April 2026 to £126 in September, and balancing costs hit record levels in October.
Overall NESO say a combination of lots of wind, not enough electricity network and high gas prices contribute to high constraint costs.
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