Negative prices
Research notes
Figures are for London unless they say otherwise.
What happened
London down to −1.9p at 12:30, below zero for 4.5 hours from 10:30. All regions negative, lowest −2.3p in Northern Scotland. Daily average 11.6p.
Likely causes
- Solar-led. Solar peaked at about 12.2GW around midday, while transmission demand was very low: total transmission-connected generation plus imports bottomed out at 16.7GW at 14:00. (confirmed by source: grid data) PV_Live 27 Apr · Elexon FUELHH 27 Apr 2025
- Wind was only moderate (averaging 6.6GW, 4.2GW at its lowest mid-afternoon), so this was mostly about sun and a quiet Sunday rather than wind. (confirmed by source: grid data, same link)
- GB was importing throughout (averaging 4.2GW), which suggests the Continent had surplus solar of its own that day. (inference)
- High pressure returned for the last week of April, the sunniest April on record. (confirmed by source) Met Office, 30 Apr 2025
Wider context that week
- The next day, Mon 28 Apr, Spain and Portugal suffered a total blackout at 12:33 CEST. Not connected to GB prices, but it dominated energy news that week and fed a debate about grids with a lot of solar. ENTSO-E · Wikipedia
- NESO's Summer Outlook (15 Apr) had warned that demand on the transmission network could fall below the 13.4GW record set in the 2020 lockdown. NESO, 15 Apr 2025
- April ended with 26.7°C at Wisley on 30 Apr. Met Office
Confidence
Medium to high. Clear in the grid data; nothing date-specific in the press.
Gaps
No news report found for this date. Same N2EX-versus-Agile question as the early April section.