Power system records

This quarter was defined by record-breaking solar output and the lowest ever carbon emissions. Solar power broke all hourly, daily, and monthly records. At 1 PM on 10 May, it supplied more than 40% of Britain’s electricity demand for the first time. That month also saw both the cleanest day on record (averaging 28 grams of CO2 per kWh of electricity consumed), and then the lowest ever instantaneous carbon intensity of just 6 g/kWh. June then extended the run of milestones, with solar power averaging more than 3.4 GW over the month, well above the previous record of 2.8 GW.

The tables below look over the past sixteen 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 second quarter of 2025. 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.