Negative prices (Storm Pia and Christmas)
Thu 21 Dec · Fri 22 Dec · Sat 23 Dec · Sun 24 Dec · Mon 25 Dec
Research notes
Figures are for London unless they say otherwise.
What happened
- Thu 21 Dec: London was below zero for 4 hours (longest spell 3 hours from 02:00), min −3.6p at 02:30; average 9.5p, peak 30.4p at 16:30; all 14 regions at 0p or below; lowest −4.3p in Northern Scotland.
- Fri 22 Dec: London was below zero for 3.5 hours (longest spell 1.5 hours from 02:30), min −0.8p at 00:00; average 9.3p, peak 27.7p at 16:30; all 14 regions at 0p or below; lowest −1.0p in Northern Scotland.
- Sat 23 Dec: London was below zero for 3.5 hours (longest spell 1 hour from 04:30), min −4.2p at 23:30; average 5.9p, peak 24.2p at 16:30; all 14 regions at 0p or below; lowest −5.0p in Northern Scotland.
- Sun 24 Dec: London was below zero for 8.5 hours (longest spell 6.5 hours from 00:00), min −2.5p at 23:30; average 2.6p, peak 19.2p at 16:30; all 14 regions at 0p or below; lowest −3.0p in Northern Scotland.
- Mon 25 Dec: London was below zero for 4.5 hours (longest spell half an hour from 00:00), min −3.1p at 00:00; average 7.1p, peak 23.1p at 16:00; all 14 regions at 0p or below; lowest −3.8p in Northern Scotland.
Likely causes
- Storm Pia, named by the Danish authorities rather than the Met Office, hit the UK on Thu 21 Dec 2023 with gusts of 81mph at Brizlee Wood in Northumberland and at Baltasound in Shetland. Source: PA via Guernsey Press, 21 Dec 2023. (confirmed by source)
- Electric Insights: Britain's wind farms "had a record-breaking month in December" 2023. Source: Electric Insights, Q4 2023. (confirmed by source)
- Christmas Eve and Christmas Day fell on the Sunday and Monday. (confirmed by the calendar)
- Thu 21 Dec, 02:30 (London's lowest half-hour): wind 20.3GW (68% of supply), solar 0GW, gas 2.5GW (8%), imports 0.7GW, total supply 30.1GW. Over the day wind averaged 20.9GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Fri 22 Dec, 00:00 (London's lowest half-hour): wind 19.7GW (65% of supply), solar 0GW, gas 2.2GW (7%), imports 1.4GW, total supply 30.2GW. Over the day wind averaged 18.4GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Sat 23 Dec, 23:30 (London's lowest half-hour): wind 19.1GW (64% of supply), solar 0GW, gas 2.5GW (9%), imports 0.3GW, total supply 29.7GW. Over the day wind averaged 18.6GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Sun 24 Dec, 23:30 (London's lowest half-hour): wind 16.6GW (61% of supply), solar 0GW, gas 2.7GW (10%), imports 0.5GW, total supply 27.2GW. Over the day wind averaged 19.2GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Mon 25 Dec, 00:00 (London's lowest half-hour): wind 16.3GW (60% of supply), solar 0GW, gas 2.8GW (10%), imports 1GW, total supply 27.3GW. Over the day wind averaged 14.3GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Wind was well above its yearly average at the lowest half-hour on Thu 21 Dec, Fri 22 Dec, Sat 23 Dec, Sun 24 Dec and Mon 25 Dec (20.3GW, 19.7GW, 19.1GW, 16.6GW and 16.3GW, against 9GW for the year). (inference from NESO data)
- The low came overnight on Thu 21 Dec, Fri 22 Dec, Sat 23 Dec, Sun 24 Dec and Mon 25 Dec, when demand is at its lowest. (inference)
- Sat 23 Dec was at the weekend, Sun 24 Dec was at the weekend and Mon 25 Dec was a bank holiday (Christmas Day), when demand is lower. (inference)
- Elexon market index: Thu 21 Dec averaged £40.58/MWh with a low of −£1.59 at 03:00; Fri 22 Dec averaged £48.87/MWh with a low of −£6.20 at 03:30; Sat 23 Dec averaged £29.46/MWh with a low of −£7.10 at 03:30; Sun 24 Dec averaged £5.60/MWh with a low of −£21.68 at 11:00; Mon 25 Dec averaged £34.45/MWh with a low of −£20.80 at 23:00. Source: Elexon market index, Thu 21 Dec. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Storm Gerrit (Wed 27 Dec to Thu 28 Dec) was within a few days of it. Source: Met Office, UK storm season 2023/24. (confirmed by source; its effect on these prices is inference)
Confidence
High.
Gaps
- None beyond what is said above.