Brief negative price at lunchtime (clock-change day)
Research notes
Figures are for London unless they say otherwise.
What happened
London touched −0.0p at 13:30, below zero for a single half-hour. The average was 11.8p and the peak only 27.3p at 18:30. All 14 regions reached zero or below, lowest −0.1p in South Western England.
Likely causes
- A very windy weekend on top of Sunday demand. The broker report for Mon 30 Mar says Friday's day-ahead baseload settled at £58.10/MWh, "well below Thursday's £113.50, reflecting the weekend demand trough and a substantial step-up in wind output", that wind averaged 16.1 GW over the week (nearly double the prior week's 8.6 GW) and that wind was dropping back on Monday "from the weekend's record levels". (confirmed by source) Prestige, 30 Mar 2026
- S&P Global reported a "near-record week" for European wind and solar in the seven days to 29 Mar, with Germany and Great Britain setting new wind peak records. (search snippet only; page returned 403) S&P Global, 30 Mar 2026
- The dip came at 13:30, the solar peak, so midday solar on top of the wind is the likely trigger. (inference)
- The clocks went forward that morning, making it a 23-hour day. That has no real effect on price but is worth a mention in a post. (fact; not a cause)
Wider context that week
- A weekend escalation: Houthi forces reportedly launched their first missile strikes on Israel and US forces struck targets inside Iran. Brent went past $116/bbl on Mon 30 Mar, its highest since mid-2022, and NBP gas was about 134 to 140p/therm. Prestige, 30 Mar 2026
- The Apr to Jun price cap (£1,641, down 7%) was about to take effect on 1 Apr, along with the 3.5p/kWh Agile reduction (see the context sections). Ofgem
Confidence
Medium to high. The windy, low-demand weekend is sourced. The solar contribution is inferred from the time of day.
Gaps
- No GB wind or solar outturn for the Sunday itself.