Energy was last better‑than‑free: yesterday Next

Research notes

Figures are for London unless they say otherwise.

What happened

• Thu 19 Jan: London peaked at 35.8p at 07:30, average 32.4p, lowest 27.3p at 00:00; highest anywhere 36.0p in Merseyside and Northern Wales.
• Fri 20 Jan: London peaked at 35.8p at 07:00, average 33.0p, lowest 27.2p at 02:00; highest anywhere 37.3p in Northern Scotland.
• Sun 22 Jan: London peaked at 36.8p at 23:00, average 32.4p, lowest 26.1p at 04:30; highest anywhere 50.8p in Northern Scotland.
• Mon 23 Jan: London peaked at 36.7p at 17:30, average 34.1p, lowest 25.8p at 04:30; highest anywhere 48.2p in Northern Scotland.
• Tue 24 Jan: London peaked at 35.8p at 06:30, average 33.3p, lowest 26.2p at 23:30; highest anywhere 42.9p in Northern Scotland.

Likely causes

• On Mon 23 Jan 2023 the ESO ran its first live Demand Flexibility Service event, paying households to cut use from 5pm to 6pm, because of "tight margins and a temperature drop"; it also told coal units to be ready, then stood them down. Source: Solar Power Portal, 23 Jan 2023. (confirmed by source)
• Thu 19 Jan, 07:30 (London's peak): wind 10GW (23% of supply), solar 0GW, gas 21.4GW (50%), imports 2.3GW, total supply 43.3GW. Over the day wind averaged 11.1GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Fri 20 Jan, 07:00 (London's peak): wind 10.3GW (25% of supply), solar 0GW, gas 20GW (50%), imports 0.8GW, total supply 40.3GW. Over the day wind averaged 9.3GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Sun 22 Jan, 23:00 (London's peak): wind 5GW (17% of supply), solar 0GW, gas 12.5GW (42%), imports 3.5GW, total supply 29.8GW. Over the day wind averaged 7.3GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Mon 23 Jan, 17:30 (London's peak): wind 5.4GW (12% of supply), solar 0GW, gas 24.2GW (53%), imports 4.7GW, total supply 46.1GW. Over the day wind averaged 5.6GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
• Tue 24 Jan, 06:30 (London's peak): wind 5.2GW (15% of supply), solar 0GW, gas 19GW (55%), imports 2.1GW, total supply 34.8GW. Over the day wind averaged 5.9GW; the 2023 average was 9GW (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 Jan, 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)
• Sun 22 Jan was at the weekend, when demand is usually lower, so high prices then are less expected. (inference)
• Elexon market index: Thu 19 Jan averaged £182.70/MWh with a high of £247.84 at 08:30; Fri 20 Jan averaged £164.71/MWh with a high of £213.02 at 07:30; Sun 22 Jan averaged £152.56/MWh with a high of £216.33 at 18:00; Mon 23 Jan averaged £175.60/MWh with a high of £235.07 at 08:30; Tue 24 Jan averaged £159.36/MWh with a high of £218.49 at 18:30. Source: Elexon market index, Thu 19 Jan. (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.