Negative prices
Fri 13 Jan · Sun 15 Jan
Research notes
Figures are for London unless they say otherwise.
What happened
- Fri 13 Jan: London reached 0p at 02:30 (1 hour at 0p in all); average 22.7p, peak 35.8p at 16:00; all 14 regions at 0p or below; lowest 0.0p in Eastern England.
- Sun 15 Jan: London was below zero for half an hour from 07:00, min −0.7p at 07:00; average 20.4p, peak 35.8p at 16:00; all 14 regions at 0p or below; lowest −0.8p in Northern Scotland.
Likely causes
- Fri 13 Jan, 02:30 (London's lowest half-hour): wind 20.3GW (66% of supply), solar 0GW, gas 3.1GW (10%), imports 0.1GW, total supply 30.9GW. Over the day wind averaged 17.4GW; the 2023 average was 9GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Sun 15 Jan, 07:00 (London's lowest half-hour): wind 19.2GW (63% of supply), solar 0GW, gas 3.7GW (12%), imports 0.8GW, total supply 30.5GW. Over the day wind averaged 13.9GW; the 2023 average was 9GW (29%). 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 Fri 13 Jan and Sun 15 Jan (20.3GW and 19.2GW, against 9GW for the year). (inference from NESO data)
- The low came overnight on Fri 13 Jan, when demand is at its lowest. (inference)
- Sun 15 Jan was at the weekend, when demand is lower. (inference)
- Elexon market index: Fri 13 Jan averaged £130.78/MWh with a low of £10.70 at 03:30; Sun 15 Jan averaged £110.77/MWh with a low of £0.25 at 01:30. Source: Elexon market index, Fri 13 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
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.