Price spike
Mon 23 Sep · Wed 25 Sep
Research notes
Figures are for London unless they say otherwise.
What happened
- Mon 23 Sep: London peaked at 41.2p at 17:30, average 20.3p, lowest 13.9p at 00:30; highest anywhere 46.9p in Northern Scotland.
- Wed 25 Sep: London peaked at 38.6p at 17:30, average 19.5p, lowest 14.3p at 05:30; highest anywhere 43.8p in Northern Scotland.
Likely causes
- Mon 23 Sep, 17:30 (London's peak): wind 6.3GW (17% of supply), solar 0.2GW, gas 17GW (45%), imports 3.4GW, total supply 37.4GW. Over the day wind averaged 5.1GW; the 2024 average was 9.4GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Wed 25 Sep, 17:30 (London's peak): wind 6.1GW (16% of supply), solar 0.4GW, gas 18GW (48%), imports 2.4GW, total supply 37.3GW. Over the day wind averaged 5.1GW; the 2024 average was 9.4GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- The peak came in the early evening on Mon 23 Sep and Wed 25 Sep, when demand is highest and there is no solar. (inference)
- Wind wasn't unusually low at the peaks, so the grid figures don't explain these prices on their own. (inference)
- Elexon market index: Mon 23 Sep averaged £79.57/MWh with a high of £104.92 at 17:30; Wed 25 Sep averaged £79.92/MWh with a high of £99.22 at 17:00. Source: Elexon market index, Mon 23 Sep. (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
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.