The newly launched National Energy System Operator (NESO) has today (8 October) published its annual Winter Outlook report for 2024/2025.
The transmission body states that the UK’s power supply/demand margins are expected to be adequate for the coming winter, with the base case de-rated margin forecast to be 5.2GW, a figure that makes up 8.8% of peak average cold spell demand.
This margin forecast is higher than that of last year, where a 4.4GW or 7.4% margin was predicted. In fact, the 2024/2025 forecast represents the highest margin since 2019/2020 and assumes a peak average cold spell demand of 59.8GW, including operating reserve.
The NESO suggests a number of reasons for the increase in margins year on year, including new interconnection routes, growth in battery energy storage system (BESS) capacity, and an increase in generation connected to the distribution network.
The forecasted figure is close to that predicted in the Early Winter Outlook, released in June under National Grid ESO, which predicted a 5.6GW or 9.4% de-rated margin.
However, much like in the Early Winter Outlook, the Winter Outlook report cautions that while capacity is expected to be sufficient, there may still be risks and “tight days” ahead over the coming colder months.

The report notes that the NESO has four main priorities in preparing for the coming winter. These include actively engaging with neighbouring transmission system operators, working closely with transmission owners to minimise the impact of network outages, developing tools to boost demand flexibility in new ways, and innovating to keep costs balanced.
Craig Dyke, director of system operations at NESO, said: “As we publish our first Winter Outlook as the National Energy System Operator, it is positive to see that margins forecast for this winter are the highest since 2019/20. This is driven by a range of factors, such as additional generation, increased storage capacity and new interconnection.
“While our margin assessment has improved from previous winters, we are continuing to monitor risks and uncertainties and, if necessary, will take steps to build resilience.
“We and the rest of the energy industry will, as always, continue to prepare for a range of potential eventualities so that we are fully prepared for this coming winter.”
Goodbye to the demand flexibility service
Earlier in the year, ESO announced that it would not operate the Demand Flexibility Service (DFS) in the same way it has since 2022/2023. With the optimistic predictions of the excess capacity the network will be able to call on this winter, the need for the DFS as a contingency is reduced.
Since its launch, the DFS has helped to balance the grid by incentivising households to use less power during peak times. Consumers could be rewarded with money off their bills if they used less power during pre-determined periods.
For the coming year, NESO has revealed that it plans to launch an evolved version of the DFS, which will operate year-round to help keep the grid balanced during periods of high demand for electricity. It has not yet been revealed when this new version of the DFS will be released, but according to NESO, the new service will allow “consumers and businesses to compete directly with power stations and renewables.”