Power system records

The last quarter of 2025 delivered another set of milestones for Britain’s electricity system, with wind leading the way. On 27 October, wind farms came within touching distance of supplying three quarters of the country’s electricity demand, and on 5 December their peak output almost topped 24 GW – both new records by a wide margin.

This capped off a record-breaking year more broadly, with 2025 seeing wind, solar, and biomass each deliver their highest annual output on record. Growing low-carbon generation helped Britain’s electricity become cleaner than ever, with average carbon intensity falling to 121 g/kWh, a fraction of a gram below the previous record set in 2024.

The tables below look over the past seventeen years (since 2009) and report the record output and share of electricity generation, plus sustained averages over a day, a month, and a calendar year. Cells highlighted in blue are records that were broken in the fourth quarter of 2025, or during 2025 as a whole. Each number links to the date it occurred on the Electric Insights website, so these records can be explored visually.

3 Note that Britain has no inter-seasonal electricity storage, so we only report on half-hourly and daily records. Elexon and National Grid only report the output of large pumped hydro storage plants.
The operation of battery, flywheel and other storage sites is not publicly available.