Negative prices (Storm Bert)
Sat 23 Nov · Sun 24 Nov · Mon 25 Nov
Research notes
Figures are for London unless they say otherwise.
What happened
- Sat 23 Nov: negative late evening only, but sharply: −3.8p in London at 22:30 (−4.5p in Northern Scotland).
- Sun 24 Nov: London averaged 6.4p and was below zero for 8 hours, including a 5.5-hour run from 01:00. Min −2.4p.
- Mon 25 Nov: below zero for 4.5 hours overnight (4-hour run from 01:00), min −2.1p, then back to a 38.2p evening peak.
Likely causes
- Storm Bert, a deep low that affected the UK from 22 to 25 Nov. Source: Met Office November and autumn 2024 stats. Highest gust 113mph at Cairn Gorm. Source: Wikipedia: Storm Bert. (confirmed by source)
- Montel reported on 26 Nov that UK day-ahead prices had ranged "from below zero" early in the week as wind generation topped 21GW during Storm Bert. Source: Montel News, 26 Nov. (confirmed by source)
- Wind's share of GB electricity hit a record 69.2% on 24 Nov, according to RenewableUK. Source: RenewableUK, 19 Dec. (confirmed by source) NESO data matches: 21.2GW of wind, 69% of supply, at 03:30 on Sun 24 Nov, which is the exact half-hour of London's lowest price. NESO historic generation mix
- Sunday was close to wall-to-wall wind: never below 19.0GW all day, averaging 20.1GW. Imports dropped to zero overnight. Source: NESO historic generation mix. (confirmed by source)
- Weekend demand. Saturday's and Sunday's negative spells were at night on a weekend; Monday's was before the working day. (inference)
- Constraint payments to switch wind farms off came to about £14.6m over 22 to 25 Nov, nearly all in Scotland. Source: Scottish Daily Express using Renewable Energy Foundation figures. (confirmed by source, same caveat about REF as above)
Wider context that week
- Fri 22 Nov: Ofgem announced the Jan to Mar 2025 price cap, up about 1% from £1,717 to £1,738. Ofgem summary letter (PDF)
- Gas was at a one-year high the same week: front-month TTF reached about €47 to €47.50/MWh on 21 to 22 Nov after Gazprom cut supply to Austria's OMV (from 16 Nov), a cold snap, and worry about the Russia to Ukraine transit deal ending at the year end. Montel News, Euronews, 22 Nov. So electricity went negative while the fuel that usually sets its price was at its dearest of the year.
- The week began with a cold snap and the most significant November snow since 2010 (morning of 21 Nov). Met Office
- Storm Bert brought severe flooding to south Wales and the UK's wettest calendar day since 3 Oct 2020. Met Office
- COP29 in Baku finished that weekend. Wikipedia
- Afterwards the wind dropped below 1.8GW and the Tuesday 26 Nov evening hour cleared at £183/MWh, a three-week high. Aurora's Marc Hedin called it "impressive price volatility" in an otherwise low-volatility year. Montel News, 26 Nov
Confidence
High. Named storm, a Montel report of sub-zero day-ahead prices tied to it, a record wind share on the Sunday, and generation data matching to the half-hour.
Gaps
Montel does not give the actual negative auction figures. Found no Octopus post about plunge pricing for this weekend.