Energy was last better‑than‑free: yesterday Next

Research notes

Figures are for London unless they say otherwise.

What happened

• Wed 7 Dec: London peaked at 82.1p at 16:30 (the Energy Price Guarantee ceiling), average 49.9p, lowest 35.8p at 02:30; highest anywhere 82.1p in Eastern England.
• Thu 8 Dec: London peaked at 82.1p at 15:30 (the Energy Price Guarantee ceiling), average 57.0p, lowest 35.8p at 22:30; highest anywhere 82.1p in Eastern England.
• Fri 9 Dec: London peaked at 82.1p at 07:30 (the Energy Price Guarantee ceiling), average 59.9p, lowest 35.8p at 02:30; highest anywhere 82.1p in Eastern England.

Likely causes

• S&P Global, 9 Dec 2022: "Spot prices in France and Great Britain registered spikes during peak demand hours with very little wind" as a cold spell set in. Source: S&P Global, 9 Dec 2022. (confirmed by source, summary only)
• Wed 7 Dec, 16:30 (London's peak): wind 9.8GW (21% of supply), solar 0GW, gas 23.2GW (50%), imports 1.7GW, total supply 46.8GW. Over the day wind averaged 9.1GW; the 2022 average was 8.8GW (27%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Thu 8 Dec, 15:30 (London's peak): wind 6.5GW (15% of supply), solar 0GW, gas 23.3GW (55%), imports 1.7GW, total supply 42.4GW. Over the day wind averaged 7.7GW; the 2022 average was 8.8GW (27%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Fri 9 Dec, 07:30 (London's peak): wind 6.9GW (17% of supply), solar 0GW, gas 21.7GW (53%), imports 2GW, total supply 41.1GW. Over the day wind averaged 5.7GW; the 2022 average was 8.8GW (27%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• The peak came in the early evening on Wed 7 Dec, when demand is highest and there is no solar. (inference)
• Elexon market index: Wed 7 Dec averaged £320.18/MWh with a high of £413.61 at 16:30; Thu 8 Dec averaged £330.59/MWh with a high of £416.09 at 15:30; Fri 9 Dec averaged £359.03/MWh with a high of £493.75 at 17:30. Source: Elexon market index, Wed 7 Dec. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)

Wider context that week

• The Energy Price Guarantee began on 1 Oct 2022, setting household electricity unit rates at 34.0p/kWh. Source: Solar Power Portal, 2022. Octopus applied it to Agile by charging 34p for any half-hour priced 34p to 52p before VAT and taking 17p off anything above, which is why so many half-hours from then to 30 Jun 2023 sit at exactly 35.8p (34p with VAT) and the highest at 82.1p. (confirmed by data in the site's store; see src/lib/events.mjs)

Confidence

High.

Gaps

• Elexon's system warnings feed has no entries before mid-2023, so warnings for these days couldn't be checked there.
• Trap: The widely quoted day-ahead price of £2,585.80/MWh is from Mon 12 Dec 2022, after this event, not these days.