Negative prices
Sun 1 Jun · Tue 3 Jun
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 1 Jun: London min -2.0p at 13:30, avg 8.1p, max 26.9p. Below zero for 4h in one spell from 12:00. All 14 regions at or below zero.
- Tue 3 Jun: London min -1.9p at 15:00, avg 6.8p, max 28.5p. Below zero for 9h, longest spell 5h from 11:00. All 14 regions at or below zero. A long negative spell on a working weekday.
- Mon 2 Jun, in between, is not in the event list.
Likely causes
- 3 Jun was the windiest day of the whole summer on the transmission system: wind averaged 13.7GW and peaked at 16.2GW, against a summer average of 6.0GW. Wind was 15 to 16GW through the 11:00 to 15:00 negative spell. (confirmed by source) Elexon FUELHH 3 Jun
- On 3 Jun Britain exported heavily: net interconnector flow reached 6.0GW of exports, and about 5.2GW was being exported at 03:30. Gas-fired output fell to 2.4GW in the afternoon. (confirmed by source) Elexon FUELHH 3 Jun
- 1 Jun was a Sunday with wind averaging 10.0GW (peak 13.3GW), solar peaking at about 9.4GW around 11:30, and the lowest gas output of almost any day of the summer (average 3.1GW, 90th of 92). Transmission demand fell to 15.1GW at 13:30 to 14:00, the same half-hour as the lowest price. (confirmed by source) Elexon FUELHH 1 Jun, PV_Live 1 Jun, INDO 1 Jun
- The weather was unsettled and windy. The Met Office daily forecast published on 3 Jun describes low pressure, showers, and for the following day "windy in the north too, with coastal gales possible early on". (confirmed by source) Met Office daily weather, 3 Jun 2025
- NESO's operator commentary says the market was "long throughout the day" on 1 Jun and "predominantly long" on 3 Jun, with thermal constraints managed in Scotland (and northern England) all day. Balancing cost £12.73m on 1 Jun and £18.62m on 3 Jun. (confirmed by source) NESO daily balancing costs, Jun 2025
- Putting those together: strong wind plus midday solar, on top of low Sunday demand on 1 Jun, and on 3 Jun simply so much wind that even weekday demand and 6GW of exports could not absorb it. (inference)
Wider context that week
- Bloomberg reported on 29 May 2025 that a wind surge had already turned UK prices negative and cut gas generation sharply, so the start of June continued a windy spell. Headline only; the article is paywalled and I did not read it. Bloomberg, 29 May 2025
- Ofgem had announced on 23 May that the price cap would fall 7% to £1,720 from 1 Jul, mainly because wholesale prices had fallen. Ofgem
- Gas fell through the quarter: Montel says NBP gas "declined by almost 25% across the quarter, ending June at GBP 26.61/MWh". Montel Q2 2025 summary
Confidence
High that wind was the driver (3 Jun was the windiest day of the summer in the data, and NESO confirms an oversupplied market). Medium on anything more specific, because no news report on these two dates was found.
Gaps
- No Bloomberg, Montel, Reuters or trade-press story specific to 1 Jun or 3 Jun 2025.
- No Met Office article found for the weekend of 31 May to 1 Jun. No named storm was involved as far as I could find.
- No Octopus blog or social post about plunge pricing on these dates.