Negative prices (overnight)
Wed 11 Oct · Fri 13 Oct · Sat 14 Oct · Sun 15 Oct
Research notes
Figures are for London unless they say otherwise.
What happened
- Wed 11 Oct: London was below zero for 3 hours (longest spell 2 hours from 01:00), min −4.2p at 02:30; average 17.5p, peak 39.9p at 17:30; all 14 regions at 0p or below; lowest −5.0p in Northern Scotland.
- Fri 13 Oct: London was below zero for 1.5 hours (longest spell half an hour from 13:30), min −3.1p at 23:30; average 15.1p, peak 30.9p at 18:30; all 14 regions at 0p or below; lowest −3.8p in Northern Scotland.
- Sat 14 Oct: London was below zero for 3 hours (longest spell 1 hour from 14:30), min −4.0p at 06:00; average 10.6p, peak 44.5p at 18:30; all 14 regions at 0p or below; lowest −4.8p in Northern Scotland.
- Sun 15 Oct: London was below zero for half an hour from 05:00, min −2.1p at 05:00; average 18.6p, peak 45.7p at 18:30; all 14 regions at 0p or below; lowest −2.5p in Northern Scotland.
Likely causes
- System warning published 13 Oct, 23:51: "Notification of National Grid Emergency Instruction to a BM Participant National Grid has issued an Emergency Instruction to BRITNED on 13/10/2023 23:01" Source: Elexon system warnings. (confirmed by source)
- Wed 11 Oct, 02:30 (London's lowest half-hour): wind 16GW (61% of supply), solar 0GW, gas 3.3GW (12%), imports 1.2GW, total supply 26.4GW. Over the day wind averaged 12.4GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Fri 13 Oct, 23:30 (London's lowest half-hour): wind 16GW (59% of supply), solar 0GW, gas 2.9GW (11%), imports 2.4GW, total supply 27GW. Over the day wind averaged 13.8GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Sat 14 Oct, 06:00 (London's lowest half-hour): wind 14.9GW (60% of supply), solar 0GW, gas 3.2GW (13%), imports 1GW, total supply 24.8GW. Over the day wind averaged 14.4GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Sun 15 Oct, 05:00 (London's lowest half-hour): wind 12.9GW (53% of supply), solar 0GW, gas 3.4GW (14%), imports 1.5GW, total supply 24.2GW. Over the day wind averaged 9GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- The low came overnight on Wed 11 Oct, Fri 13 Oct, Sat 14 Oct and Sun 15 Oct, when demand is at its lowest (total supply as low as 24.2GW, against a 2023 average of 31.3GW). (inference)
- Sat 14 Oct and Sun 15 Oct were at the weekend, when demand is lower. (inference)
- Elexon market index: Wed 11 Oct averaged £89.41/MWh with a low of −£11.42 at 04:00; Fri 13 Oct averaged £77.41/MWh with a low of −£7.11 at 23:30; Sat 14 Oct averaged £37.16/MWh with a low of −£17.58 at 06:00; Sun 15 Oct averaged £78.53/MWh with a low of −£0.53 at 05:00. Source: Elexon market index, Wed 11 Oct. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Storm Babet (Wed 18 Oct to Sat 21 Oct) 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
Low. Neither the grid figures nor any report found clearly explain this date.
Gaps
- No news report or official write-up found that ties this date to a cause; the causes above are from the data.