Negative prices (windy weekday)
Research notes
Figures are for London unless they say otherwise.
What happened
London dipped to −0.6p at 13:30 and was below zero for 2.5 hours (longest spell 2h from 13:30). All regions at or below zero, lowest −0.7p in Northern Scotland. Daily average 9.9p.
Likely causes
- Bloomberg, 29 May: blustery conditions meant wind supplied 59% of UK power on Thursday morning, gas generation fell to 1.2GW, its lowest since October and under a quarter of the previous month's average, and the wind surge briefly pushed intraday prices below zero. (confirmed by source; paywalled, details from headline and search summary) Bloomberg, 29 May 2025
- Grid data matches closely: gas bottomed at 1,243MW at 09:30; transmission-metered wind climbed from 6.2GW just after midnight to 16.0GW at 14:30, which is when Agile went negative; solar added about 8.7GW; and GB was exporting 4.1GW at 14:30. (confirmed by source: grid data) Elexon FUELHH 29 May 2025 · PV_Live 29 May
- The Met Office had forecast "often strong winds" through half-term week as Atlantic systems kept arriving. (confirmed by source) Met Office, 21 May 2025
- A weekday going negative is less common than a weekend; half-term week may have softened demand a little. (inference)
Wider context that week
- Drax published its Q1 2025 Electric Insights report this week, noting solar output up 40% and warning that transmission demand could fall below 13.4GW. Drax Electric Insights Q1 2025
- Gas was cheap by recent standards: Montel reports gas prices fell almost 25% across Q2 2025. Montel GB Q2 2025 summary
Confidence
High. Bloomberg report on the day plus matching grid data.
Gaps
Could not read the full Bloomberg article. No named storm or Met Office warning found for 29 May.