Negative prices (overnight, weekend)
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 19 Nov: London was below zero for 4 hours (longest spell 3 hours from 02:30), min −4.2p at 01:30; average 15.2p, peak 41.2p at 16:30; all 14 regions at 0p or below; lowest −5.0p in Northern Scotland.
Likely causes
- Sun 19 Nov, 01:30 (London's lowest half-hour): wind 17.5GW (65% of supply), solar 0GW, gas 3.2GW (12%), imports 0.9GW, total supply 26.8GW. Over the day wind averaged 15.7GW; 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 Sun 19 Nov (17.5GW, against 9GW for the year). (inference from NESO data)
- The low came overnight on Sun 19 Nov, when demand is at its lowest. (inference)
- Sun 19 Nov was at the weekend, when demand is lower. (inference)
- Elexon market index: Sun 19 Nov averaged £61.58/MWh with a low of −£12.94 at 06:00. Source: Elexon market index, Sun 19 Nov. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Storm Debi affected the UK on 13 Nov 2023. Source: Met Office, UK storm season 2023/24.
Confidence
Medium. The grid figures fit the prices, but no report found names a cause for 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.