Price spike (at the cap)
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 10 Jan: London peaked at 35.0p at 17:00 (Agile's 35p cap), average 15.6p, lowest 11.6p at 07:00; highest anywhere 35.0p in Eastern England.
Likely causes
- See the 5 to 9 Jan 2021 event: margins were tight throughout January, and day-ahead prices rose to £1,063/MWh on 13 Jan, "their highest since 1995". Source: Electric Insights, Cold weather and tight margins (Q1 2021). (confirmed by source)
- Sun 10 Jan, 17:00 (London's peak): wind 8.7GW (19% of supply), solar 0GW, gas 21.1GW (46%), imports 3.2GW, total supply 45.7GW. Over the day wind averaged 7.5GW; the 2021 average was 7.1GW (22%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- The peak came in the early evening on Sun 10 Jan, when demand is highest and there is no solar. (inference)
- Sun 10 Jan was at the weekend, when demand is usually lower, so high prices then are less expected. (inference)
- Elexon market index: Sun 10 Jan averaged £63.26/MWh with a high of £85.81 at 17:00. Source: Elexon market index, Sun 10 Jan. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Agile was capped at 35p per kWh for new customers until 22 Jul 2022 (the version Agile launched with, AGILE-18-02-21; see
src/lib/products.mjs), so a "high" day before then is one where the evening peak reached that cap. (confirmed by data: the capped half-hours sit at exactly 35.0p)
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.
- Elexon's system warnings feed has no entries before mid-2023, so warnings for these days couldn't be checked there.