Negative prices (overnight)
Mon 15 Apr · Tue 16 Apr
Research notes
Figures are for London unless they say otherwise.
What happened
- Mon 15 Apr: London was below zero for 1.5 hours (longest spell 1 hour from 03:00), min −1.0p at 05:00; average 7.9p, peak 26.7p at 18:30; all 14 regions at 0p or below; lowest −1.2p in Northern Scotland.
- Tue 16 Apr: London was below zero for half an hour from 03:30, min −0.6p at 03:30; average 10.8p, peak 29.8p at 18:30; all 14 regions at 0p or below; lowest −0.7p in Northern Scotland.
Likely causes
- Mon 15 Apr, 05:00 (London's lowest half-hour): wind 18.3GW (61% of supply), solar 0GW, gas 3.1GW (10%), imports 0.7GW, total supply 29.7GW. Over the day wind averaged 18.9GW; the 2024 average was 9.4GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Tue 16 Apr, 03:30 (London's lowest half-hour): wind 17.6GW (62% of supply), solar 0GW, gas 2.3GW (8%), imports 1.4GW, total supply 28.6GW. Over the day wind averaged 15.2GW; the 2024 average was 9.4GW (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 Mon 15 Apr and Tue 16 Apr (18.3GW and 17.6GW, against 9.4GW for the year). (inference from NESO data)
- The low came overnight on Mon 15 Apr and Tue 16 Apr, when demand is at its lowest. (inference)
- Elexon market index: Mon 15 Apr averaged £19.08/MWh with a low of −£9.73 at 15:00; Tue 16 Apr averaged £55.11/MWh with a low of −£10.60 at 03:30. Source: Elexon market index, Mon 15 Apr. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Nothing notable found for that week.
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.