Battery storage helps UK winter power margins, says NESO

In Brief

NESO expects Great Britain to have enough electricity available through winter 2026/27.

Its early forecast shows a 5.5 GW spare power margin – essentially the buffer between expected peak demand and available supply.

That equates to an 8.8% cushion over expected peak demand during a typical cold spell.

Battery storage, new gas generation and more renewable generation are helping offset rising electricity demand.

NESO still expects some tighter days, particularly in January, when it may need to ask the market for extra support.

In Review

Great Britain is expected to have enough electricity available through winter 2026/27, helped by the growth of battery storage, new generation and renewable capacity, according to the National Energy System Operator.

NESO’s early winter view forecasts a 5.5 GW spare margin for the period from October 31, 2026 to March 31, 2027. In simple terms, that is the expected buffer between peak electricity demand and available supply, after NESO has adjusted for how likely different types of generation are to be available when needed.

That does not mean every day will be easy to manage. NESO says there may still be tighter periods, with current market submissions suggesting these are most likely in mid-to-late January. But overall, the system operator expects the adequacy position to remain broadly comparable with recent winters.

The reason the margin is holding up is that rising demand is being offset by new capacity. NESO points to increased battery storage, new gas-fired generation and growth in wind generation as key contributors. The T-1 Capacity Market auction for delivery in winter 2026/27 also secured 7.2 GW of new and existing capacity across a range of technologies.

This is all coming despite the fact that electricity demand is still expected to rise as more parts of the economy electrify. EVs, heat pumps, industrial processes and data centres are all adding pressure to the system.

Data centres are one of the more significant emerging loads. NESO recently submitted an analysis to Parliament where it suggested that there will be around 5.2 GW of connected data centre capacity and just over 20 TWh of annual electricity consumption by 2030. It also notes that nearly 59 GW of data centre projects are currently awaiting transmission-level connection, although NESO does not expect all of that demand to connect.

NESO expects enough operational surplus throughout the winter across a wide range of scenarios for demand, wind output, generator availability and interconnector performance. It also says Great Britain should be able to support exports to neighbouring markets when required.

However, the market position remains sensitive. Forward wholesale prices suggest Great Britain is likely to be a net importer across electricity interconnectors this winter, with UK prices trading at a premium to France. NESO says gas and power prices remain higher than winter 2025/26 levels, although still well below the peaks seen in 2022.

For large energy users, the message is reassuring, but not a reason to relax completely. A healthier national margin reduces the risk of a difficult winter, but site-level flexibility still matters. Storage, demand response, good controls and properly commissioned energy management systems all help reduce exposure when the system is tighter or prices are higher.

The longer-term lesson is fairly clear. More generation helps, but more flexible capacity is just as important. If battery storage, flexible demand and grid connections can be delivered faster and operated well, future winters should have more breathing room. If they are delayed, underused or poorly integrated, the headline margin will not tell the whole story.