Zero and negative prices (record wind)
Sun 15 Dec · Mon 16 Dec
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 15 Dec: London touched 0.0p at 22:30; average 12.6p.
- Mon 16 Dec: two negative half-hours before dawn (02:30 and 05:00), min −0.6p; average 15.3p.
- Three days earlier the price had been at the 100p cap.
Likely causes
- An all-time GB wind generation record was set at 18:30 on Sun 15 Dec, confirmed by NESO. Sources disagree on the figure: Solar Power Portal gives 22,243MW (beating 21,998MW from 10 Jan 2023); Review Energy and RenewableUK give 22.4GW (beating 21.8GW from 21 Dec 2023), supplying 54% of electricity at the time. NESO's half-hourly dataset shows 22.2GW at 18:30, which supports the 22,243MW version. Sources: Solar Power Portal, 20 Dec, Review Energy, 18 Dec, NESO historic generation mix. (confirmed by source that a record was set; the exact figure is disputed)
- Wind stayed above 17GW for the whole of both days, averaging 20.2GW on Sunday and 20.0GW on Monday. At 22:30 Sunday it was 21.6GW (64% of supply); at 05:00 Monday 21.1GW (65%). Source: NESO historic generation mix. Figures (confirmed by source); link to price (inference).
- Low demand: Sunday night, then the small hours of Monday. (inference)
Wider context that week
- The record fell again within days: 22,523MW at 03:30 on Wed 18 Dec, 68.3% of GB electricity. RenewableUK's Dan McGrail: "Setting another clean electricity generation record just four days after the previous high shows the pivotal role wind is playing". RenewableUK, 19 Dec
- Half-hourly wholesale prices went negative on Wed 18 Dec between 05:30 and 06:30, touching −£6.57/MWh, and the UK had by then seen 131 negative-price hours in 2024, 45 more than in 2023. EcoWatch, 19 Dec, Bloomberg, 18 Dec. Note that 18 Dec is not in the data file as a zero or negative Agile day, so the wholesale dip evidently did not carry through to Agile after its multiplier and adders. Worth a look in the site's own data before mentioning it.
- The cost of wasted wind on 18 Dec was put at £12.6m (£4.2m to turn turbines off, £8.5m to buy power elsewhere). Solar Power Portal, 20 Dec
- Hansard has the Commons statement on the Clean Power 2030 Action Plan on Mon 16 Dec. Hansard
Confidence
High that record wind caused these prices: the record was set four hours before Sunday's zero price. Medium on the exact record figure because sources differ.
Gaps
Did not find NESO's own announcement of the 15 Dec record (only trade press relaying it). No named storm was involved; I found no Met Office write-up of the 15 to 16 Dec weather.