Storage

Storage covers pumped hydro and battery systems. Positive figures mean storage is discharging (generating); negative figures mean it is charging (consuming power to store for later).

Current output
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Share of generation
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Breakdown

SourceGW%
Pumped hydro--

Batteries

Nobody publishes a measured total for Great Britain's batteries as it happens. So this adds up the battery units registered in the Balancing Mechanism, using Elexon's data. Charging is shown as negative.

Batteries right now (notified)
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Charging
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Discharging
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Notified, last 24 hours

Notified figures are what each battery told NESO it plans to do in each half hour, about an hour ahead. They are plans, not measurements: NESO's instructions can change what a battery actually does.

Metered, latest 7 days published

Metered figures are what each battery actually did. Elexon publishes them about a week later.

These figures cover only batteries registered in the Balancing Mechanism. Smaller batteries outside it, including home batteries, are not included. Elexon does not label units as batteries, so they are picked out from Elexon's register by name, ID and the ability to both charge and discharge. Battery output is not shown separately in Elexon's generation by fuel type, so it is not added to the mix elsewhere on this site.

Sources

  • Elexon Insights Solution - Physical Notifications (PN) for notified output, B1610 actual generation output per unit for metered output, and the BM unit register. Contains BMRS data © Elexon Limited copyright and database right 2026.
  • NESO: historic generation mix - "Batteries (NET discharge) are currently included in the OTHER category". Checked 29 October 2026.

History

Storage output and share of total generation over the selected range.

About storage

Pumped hydro stations, such as Dinorwig in Wales, pump water uphill when power is cheap or abundant, then release it through turbines within seconds when demand spikes - acting as a giant battery for the grid.

Dinorwig and the birth of grid-scale storage

Dinorwig power station, built inside a mountain in Snowdonia and completed in 1984, remains one of the most remarkable feats of British energy engineering. Nicknamed "Electric Mountain", it can go from a standing start to generating 1.7GW of power in about 12 seconds (its owner, ENGIE), historically used to cover the sudden surges in demand that occur, famously, when millions of kettles are switched on during breaks in televised events. Britain's other major pumped storage sites - Ffestiniog (1963), Cruachan in Scotland (1965), and Foyers (1974) - are older still, built as some of Europe's earliest large-scale grid storage.

The rise of batteries

Grid-scale battery storage is far newer, with the first significant projects connecting in the mid-2010s as lithium-ion battery costs fell sharply. Battery capacity has since grown far faster than pumped hydro ever could, because battery sites can be built in months rather than the decade-plus required for a new pumped storage scheme, and can be sited almost anywhere on the network.

Batteries typically discharge for shorter bursts than pumped hydro - commonly half an hour to two hours - making them well suited to smoothing short-term mismatches between renewable output and demand, and to providing fast frequency response that keeps the grid stable moment to moment.

The growth is now very fast. Government statistics put UK grid-scale battery capacity at 7.5GW by the end of 2025, after a record 2.3GW was connected during that year, and Great Britain's batteries supplied 2.3TWh in 2025, up from 0.8TWh in 2023. They are also slightly more efficient than pumped hydro: in 2025 batteries returned 85% of the energy put into them, against 81% for pumped storage (DESNZ). The industry body RenewableUK counted 8.7GW / 14.1GWh operational across the UK by 12 October 2026, with around 9.1GW / 19GWh more under construction. The government's Clean Power 2030 plan aims for 23-27GW of batteries by 2030.

Different counts of battery capacity do not always match: DESNZ's figure scales up the batteries registered in Elexon's Balancing Mechanism (by about 1.3 times) to include smaller sites that are not registered, the government's July 2026 flexibility roadmap quotes 7.3GW for June 2026 from Modo Energy's tracking, and RenewableUK's database counts projects individually and models some sizes where specifications are not published.

Elexon's generation by fuel type has no battery category, and NESO's historic generation mix counts battery discharge inside "Other" and leaves charging out. The Batteries section above adds up the battery units in the Balancing Mechanism instead.

Sources

Records

The storage facts below are real and sourced, hand-checked periodically against the sources below (see "Last checked") rather than computed live from this site's own stored history, which for a fresh install would only cover a few days or weeks rather than a full year.

  • Highest pumped storage discharge (past 12 months)2.7GW - 8 January 2026
  • Dinorwig start-to-full-power time0 to 1,320MW in about 12 seconds
  • Dinorwig opened9 May 1984
  • UK grid-scale battery capacity, end of 2025 (official)7.5GW - DESNZ
  • Most battery capacity connected in one year2.3GW - 2025 (DESNZ)
  • GB battery output in a year2.3TWh - 2025, up from 0.8TWh in 2023 (DESNZ)
  • UK battery capacity operational, latest industry count8.7GW / 14.1GWh - 12 October 2026 (RenewableUK)
  • Battery capacity under constructionAbout 9.1GW / 19GWh - October 2026 (RenewableUK)
  • Long-duration storage (mostly pumped hydro)2.8GW / 23.9GWh - June 2026 (NESO, via DESNZ)
  • Average efficiency, 2025Batteries 85%, pumped storage 81% (DESNZ)

Source: National Energy System Operator (Elexon BMRS for the "past 12 months" figure) and ENGIE (owner of First Hydro), Dinorwig Power Station; battery and long-duration storage figures from DESNZ grid-scale battery storage statistics, the DESNZ Clean flexibility roadmap and RenewableUK EnergyPulse. Battery figures last checked: 28 October 2026; pumped storage figures: 2 October 2026.