Negative prices (as lockdown eased)
Sun 5 Jul · Mon 6 Jul
Research notes
Figures are for London unless they say otherwise.
What happened
- Sun 5 Jul: London was below zero for 7 hours (longest spell 4.5 hours from 04:00), min −4.0p at 15:00; average 3.2p, peak 18.7p at 18:00; all 14 regions at 0p or below; lowest −4.8p in Northern Scotland.
- Mon 6 Jul: London was below zero for 1.5 hours (longest spell half an hour from 02:30), min −0.6p at 02:30; average 6.8p, peak 21.0p at 16:30; all 14 regions at 0p or below; lowest −0.8p in Northern Scotland.
Likely causes
- Sun 5 Jul, 15:00 (London's lowest half-hour): wind 12.8GW (41% of supply), solar 6.4GW, gas 5.5GW (18%), imports 0GW, total supply 31.5GW. Over the day wind averaged 12.7GW; the 2020 average was 7.8GW (25%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Mon 6 Jul, 02:30 (London's lowest half-hour): wind 12.1GW (54% of supply), solar 0GW, gas 3.3GW (15%), imports 0.5GW, total supply 22.3GW. Over the day wind averaged 9.8GW; 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 Jul, with solar at 6.4GW. (inference from NESO data)
- The low came overnight on Mon 6 Jul, when demand is at its lowest (total supply as low as 22.3GW, against a 2020 average of 31.4GW). (inference)
- Sun 5 Jul was at the weekend, when demand is lower. (inference)
- Elexon market index: Sun 5 Jul averaged £9.72/MWh with a low of −£25.30 at 01:00; Mon 6 Jul averaged £19.36/MWh with a low of −£45.73 at 01:30. Source: Elexon market index, Sun 5 Jul. (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.