Negative prices (lockdown)
Research notes
Figures are for London unless they say otherwise.
What happened
- Sat 6 Jun: London was below zero for 4.5 hours (longest spell 3 hours from 03:30), min −2.0p at 05:30; average 4.8p, peak 21.2p at 18:30; all 14 regions at 0p or below; lowest −2.4p in Northern Scotland.
Likely causes
- Sat 6 Jun, 05:30 (London's lowest half-hour): wind 11.7GW (51% of supply), solar 0.2GW, gas 4.4GW (19%), imports 0.6GW, total supply 22.7GW. Over the day wind averaged 11.5GW; the 2020 average was 7.8GW (25%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- The low came overnight on Sat 6 Jun, when demand is at its lowest (total supply as low as 22.7GW, against a 2020 average of 31.4GW). (inference)
- Sat 6 Jun was at the weekend, when demand is lower. (inference)
- Elexon market index: Sat 6 Jun averaged £6.33/MWh with a low of −£31.75 at 05:00. Source: Elexon market index, Sat 6 Jun. (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
Low. Neither the grid figures nor any report found clearly explain 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.