Negative prices
Fri 9 Aug · Sat 10 Aug · Mon 12 Aug
Research notes
Figures are for London unless they say otherwise.
What happened
- Fri 9 Aug: London was below zero for 8.5 hours (longest spell 5 hours from 10:30), min −3.0p at 02:30; average 5.2p, peak 24.6p at 18:30; all 14 regions at 0p or below; lowest −3.6p in Northern Scotland.
- Sat 10 Aug: London was below zero for 2 hours (longest spell 1 hour from 12:00), min −1.1p at 13:30; average 8.2p, peak 30.6p at 18:00; all 14 regions at 0p or below; lowest −1.4p in Northern Scotland.
- Mon 12 Aug: London was below zero for 1.5 hours (longest spell half an hour from 01:30), min −0.4p at 01:30; average 11.3p, peak 35.7p at 18:30; all 14 regions at 0p or below; lowest −0.5p in Northern Scotland.
Likely causes
- Fri 9 Aug, 02:30 (London's lowest half-hour): wind 17.4GW (65% of supply), solar 0GW, gas 2.8GW (10%), imports 0GW, total supply 26.7GW. 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)
- Sat 10 Aug, 13:30 (London's lowest half-hour): wind 12.3GW (39% of supply), solar 5.2GW, gas 2.1GW (7%), imports 4.8GW, total supply 31.5GW. Over the day wind averaged 9.9GW; the 2024 average was 9.4GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Mon 12 Aug, 01:30 (London's lowest half-hour): wind 14.2GW (55% of supply), solar 0GW, gas 2.5GW (10%), imports 0.9GW, total supply 26GW. Over the day wind averaged 11.7GW; 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 Fri 9 Aug (17.4GW, against 9.4GW for the year). (inference from NESO data)
- The low came around midday on Sat 10 Aug, with solar at 5.2GW. (inference from NESO data)
- The low came overnight on Fri 9 Aug and Mon 12 Aug, when demand is at its lowest. (inference)
- Sat 10 Aug was at the weekend, when demand is lower. (inference)
- Elexon market index: Fri 9 Aug averaged £17.66/MWh with a low of −£17.82 at 15:00; Sat 10 Aug averaged £21.30/MWh with a low of −£30.08 at 14:30; Mon 12 Aug averaged £43.74/MWh with a low of −£15.11 at 03:30. Source: Elexon market index, Fri 9 Aug. (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.