The National Energy System Operator (NESO) has released its 2025 Early View of Winter, projecting the strongest electricity operational margins for the UK grid since 2019.
The report, published on 18 June, provides an initial outlook for managing the country’s electricity transmission network during the 2025/26 winter period, running from 31 October to 31 March.
According to NESO, this winter’s operational margin is expected to reach 6.6GW, or 10.9% of demand, marking a notable improvement from the 5.2GW margin forecast in last year’s Winter Outlook.
The 6.6GW figure represents the highest anticipated margin since the 2019/20 winter.
Operational margins refer to the surplus electricity available above that needed to meet real-time demand and to maintain reserves.
These reserves are essential for ensuring safe, continuous operation of the network, particularly during periods of high usage or generation shortfall.
The improved margin is being driven by several key developments. NESO attributes the increase to rising contributions from battery storage, both at the national transmission and local distribution levels.
An uptick in the availability of gas-fired electricity generation has also played a role. In addition, the recent commissioning of the Greenlink electricity interconnector between Ireland and Wales has added valuable cross-border capacity.
Note of caution
Despite the generally positive outlook, NESO cautions that the winter period may still include some tight days.
During such times, NESO’s control room engineers may need to employ standard operational tools to balance supply and demand.
These tools include Capacity Market Notices and Electricity Market Notices, which signal to generators such as wind farms, battery operators or power stations that additional electricity may be required.
The issuance of these notices does not necessarily indicate a shortfall in supply but is a routine aspect of winter grid management.
Dr Deborah Petterson, Director of Resilience and Emergency Management at NESO, emphasised the importance of continued vigilance.
Our early view of the winter ahead shows a positive outlook with sufficient margins throughout the colder winter months. We will continue to monitor developments in global energy markets, remaining vigilant in our preparations to ensure that the resilience and reliability of the electricity network is maintained.”
A more detailed Winter Outlook report will be published later this year, offering final projections and further operational planning for the 2025/26 season.
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