Energy was last better‑than‑free: yesterday Next

On the Agile Octopus tariff, customers get paid to use electricity when there’s too much in the grid.

That’s cheaper than Octopus Energy paying to store it.

The price changes every half-hour.

Period

Region

Negative prices in the middle of the expensive run

Figures are for London unless they say otherwise.

What happened. London down to −2.7p at 11:00, below zero for 5 hours, yet the day averaged 22.0p with a 47.3p peak at 17:30.

Likely causes

Wind rose from 5 GW at midnight to 16.3 GW by midday (daily max 16.9 GW) and then fell away again through the evening; solar added 6 to 8 GW. At 11:00 gas plant was at 2.9 GW and Britain was exporting (confirmed by data) Elexon FUELHH 12 Sep
Friday's day-ahead for the weekend collapsed: baseload £117.34 (down £58.66) and peak £69.68 (down £105.26) (confirmed by source) Catalyst 14 Sep
Saturday demand (inference).

Wider context. Gas was still about 199p, so as soon as the wind eased the evening went straight back to 47p. Same week as the section above.

Confidence. High.

Gaps. None beyond the lack of press coverage.

Saturday 12 Sep 2026 · half-hourly prices

South Eastern England

−2.6p

Cheapest half-hour 11am – 11.30am

51.1p

Dearest half-hour 5.30pm – 6pm

5 hours

Negative prices in 2 spells

−2.4p avg

Cheapest 3 hours 10.30am – 1.30pm

24.4p

Average price on 12 Sep 2026

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