Negative prices (lockdown)
Sun 5 Apr · Mon 6 Apr
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 5 Apr: London was below zero for 6 hours (longest spell 5.5 hours from 10:30), min −3.1p at 14:00; average 3.7p, peak 19.0p at 18:30; all 14 regions at 0p or below; lowest −3.8p in Northern Scotland.
- Mon 6 Apr: London was below zero for 1 hour from 03:30, min −0.3p at 03:30; average 6.0p, peak 21.3p at 18:30; all 14 regions at 0p or below; lowest −0.4p in Northern Scotland.
Likely causes
- Octopus, on 8 Apr 2020: with "social distancing plus sunny, windy weather", "prices even go negative, and customers are paid for the power they use"; "when demand is lower than usual, the grid can end up with too much power". Source: Octopus Energy blog, 8 Apr 2020. (confirmed by source)
- Sun 5 Apr, 14:00 (London's lowest half-hour): wind 12.8GW (41% of supply), solar 7.6GW, gas 4.9GW (16%), imports 0.7GW, total supply 31.6GW. Over the day wind averaged 13.3GW; the 2020 average was 7.8GW (25%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Mon 6 Apr, 03:30 (London's lowest half-hour): wind 13.3GW (57% of supply), solar 0GW, gas 3.9GW (17%), imports 0.6GW, total supply 23.5GW. Over the day wind averaged 10.3GW; the 2020 average was 7.8GW (25%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- The low came around midday on Sun 5 Apr, with solar at 7.6GW. (inference from NESO data)
- The low came overnight on Mon 6 Apr, when demand is at its lowest (total supply as low as 23.5GW, against a 2020 average of 31.4GW). (inference)
- Sun 5 Apr was at the weekend, when demand is lower. (inference)
- Elexon market index: Sun 5 Apr averaged £4.95/MWh with a low of −£36.91 at 23:30; Mon 6 Apr averaged £15.81/MWh with a low of −£34.40 at 05:00. Source: Elexon market index, Sun 5 Apr. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- The first national lockdown in England began on 23 Mar 2020 ("stay at home"); people who couldn't work from home were asked to return from 10 May, non-essential shops reopened on 15 Jun, and pubs and restaurants on 4 Jul. Source: GOV.UK, timeline of COVID-19 restrictions in 2020 (PDF). (confirmed by source)
- Elexon found that GB electricity demand was 19% lower in Apr and May 2020 than a year earlier, "driven by the COVID-19 lockdown measures", and that 83% of the year's negative system prices to June fell in April and May. Source: Elexon: negative system prices during COVID-19, last updated 29 Jun 2020. (confirmed by source; these are system prices, not the day-ahead prices Agile follows)
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.