Price spike (Agile hit the 100p cap)
Research notes
Figures are for London unless they say otherwise.
What happened
London averaged 37.4p and peaked at 96.6p at 16:30. Eastern England hit the 100p cap. The day started cheap (12.1p at midnight).
Likely causes
- NESO issued an Electricity Margin Notice on the evening of 7 Jan for 16:00 to 19:00 on 8 Jan, because of low wind, plant outages and cold weather. It also issued and then cancelled a Capacity Market Notice. (confirmed by source) Solar Power Portal, 9 Jan 2025
- The size of the shortfall is reported differently: Solar Power Portal gives a 1,700MW shortfall against a 900MW contingency requirement; Reuters gives 1,120MW. These are probably figures from different updates of the notice through the day, but that is a guess. (sources conflict) Reuters via Yahoo Finance, 8 Jan 2025
- Day-ahead prices reached £300 to £400/MWh for the evening, the Balancing Mechanism spiked to £2,900/MWh from 15:00, and the report explicitly notes Octopus Agile hitting £1/kWh. (confirmed by source) Solar Power Portal, 9 Jan 2025
- Intraday prices on Epex reached £1,778.34/MWh at 17:30. Wind was below 3GW in the afternoon, gas plants were generating about 25GW, and average temperatures were just above freezing with Met Office snow and ice warnings. (confirmed by source) Bloomberg via Energy Connects, 8 Jan 2025
- Wind collapsed during the day: transmission-metered wind was 13.4GW at midnight and 2.3GW by 21:30. Gas peaked at 24.5GW at 16:30 and imports at 6.0GW at 18:00. This explains why the day began cheap and ended at the cap. (confirmed by source: grid data) Elexon FUELHH 8 Jan 2025
- NESO had little room left because GB was already importing about 5GW (Shivam Malhotra, LCP Delta). The Viking Link to Denmark was brought back from a planned outage a day early, adding 0.7GW; the Demand Flexibility Service delivered about 184MW; and NESO accepted very expensive offers from the Rye House and Connah's Quay gas plants. (confirmed by source) Solar Power Portal, 9 Jan 2025
- The Telegraph reported that spare capacity fell to 580MW at 17:30, that the two gas plants were paid about £12m for three hours, and that demand came in at 46.8GW against a 44.4GW forecast. Consultant Kathryn Porter said the market came "within a whisker of blackouts". NESO's Craig Dyke disputed that, saying supply never fell below demand and 1.4GW of emergency reserve went unused; Cornwall Insight's Tom Edwards also disagreed with the blackout framing. Present this as a disputed claim. (confirmed by source) Telegraph via Yahoo, 9 Jan 2025 · Telegraph via Yahoo, 8 Jan 2025
- Drax Electric Insights later summarised it as wind dropping suddenly in the New Year and prices hitting £2,900/MWh, about 40 times average, on 8 Jan. (confirmed by source) Drax Electric Insights Q4 2024
- NESO's balancing costs for the day were reported at £21m. (confirmed by source) The Conversation, Oct 2025
Wider context that week
- The cold spell ran from 2 Jan; see the 10 Jan section for the gas storage story, which broke two days later.
- 2025's peak electricity demand, 45,851MW, came the next day, 9 Jan at 17:00. NESO 2025 review
Confidence
High. Multiple independent reports plus grid data, and one of them names Agile directly.
Gaps
Did not find NESO's own notice text, only reports of it. The exact day-ahead hourly peak for the 16:30 period was not found, only the £300 to £400 range.