Negative prices (overnight)
Thu 10 Nov · Fri 11 Nov
Research notes
Figures are for London unless they say otherwise.
What happened
- Thu 10 Nov: London was below zero for half an hour from 23:30, min −2.9p at 23:30; average 18.3p, peak 35.8p at 16:00; all 14 regions at 0p or below; lowest −3.5p in Northern Scotland.
- Fri 11 Nov: London was below zero for 4.5 hours (longest spell 2 hours from 04:00), min −5.0p at 04:00; average 16.8p, peak 35.8p at 16:30; all 14 regions at 0p or below; lowest −6.0p in Northern Scotland.
Likely causes
- Thu 10 Nov, 23:30 (London's lowest half-hour): wind 17.2GW (56% of supply), solar 0GW, gas 4.4GW (14%), imports 1.3GW, total supply 30.5GW. Over the day wind averaged 18.1GW; the 2022 average was 8.8GW (27%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Fri 11 Nov, 04:00 (London's lowest half-hour): wind 16.4GW (58% of supply), solar 0GW, gas 3.9GW (14%), imports 0.3GW, total supply 28.2GW. Over the day wind averaged 16.7GW; the 2022 average was 8.8GW (27%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Wind was well above its yearly average at the lowest half-hour on Thu 10 Nov and Fri 11 Nov (17.2GW and 16.4GW, against 8.8GW for the year). (inference from NESO data)
- The low came overnight on Thu 10 Nov and Fri 11 Nov, when demand is at its lowest. (inference)
- Elexon market index: Thu 10 Nov averaged £54.45/MWh with a low of −£57.65 at 04:00; Fri 11 Nov averaged £63.50/MWh with a low of −£64.38 at 05:00. Source: Elexon market index, Thu 10 Nov. (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
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.