Negative prices (midday, weekend)
Sat 8 Jun · Sun 9 Jun
Research notes
Figures are for London unless they say otherwise.
What happened
- Sat 8 Jun: London was below zero for 4.5 hours from 11:00, min −8.4p at 13:30; average 8.0p, peak 29.4p at 18:30; all 14 regions at 0p or below; lowest −10.1p in Northern Scotland.
- Sun 9 Jun: London was below zero for 3 hours (longest spell 1.5 hours from 10:00), min −2.0p at 10:00; average 8.8p, peak 31.5p at 18:30; all 14 regions at 0p or below; lowest −2.4p in Northern Scotland.
Likely causes
- Sat 8 Jun, 13:30 (London's lowest half-hour): wind 12.3GW (37% of supply), solar 8.3GW, gas 2.5GW (7%), imports 4.5GW, total supply 33.3GW. Over the day wind averaged 10.3GW; the 2024 average was 9.4GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Sun 9 Jun, 10:00 (London's lowest half-hour): wind 10.3GW (34% of supply), solar 6.2GW, gas 2.2GW (7%), imports 5.7GW, total supply 29.9GW. Over the day wind averaged 9.4GW; the 2024 average was 9.4GW (29%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- The low came around midday on Sat 8 Jun and Sun 9 Jun, with solar at 8.3GW and 6.2GW. (inference from NESO data)
- Sat 8 Jun and Sun 9 Jun were at the weekend, when demand is lower. (inference)
- Elexon market index: Sat 8 Jun averaged £31.64/MWh with a low of −£13.45 at 14:30; Sun 9 Jun averaged £40.07/MWh with a low of −£19.66 at 10:00. Source: Elexon market index, Sat 8 Jun. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Electric Insights: solar output hit a record 10.7GW on 2 Jun 2024. Source: Electric Insights, Power system records (Q2 2024). (confirmed by source)
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.