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

Price spike (at the cap)

Tue 29 Sep · Thu 1 Oct

Figures are for London unless they say otherwise.

Tue 29 Sep: London peaked at 35.0p at 18:00 (Agile's 35p cap), average 13.3p, lowest 6.7p at 02:30; highest anywhere 35.0p in Eastern England.
Thu 1 Oct: London peaked at 35.0p at 17:30 (Agile's 35p cap), average 13.0p, lowest 6.4p at 03:00; highest anywhere 35.0p in Eastern England.

Tue 29 Sep, 18:00 (London's peak): wind 2.2GW (6% of supply), solar 0.1GW, gas 19.7GW (54%), imports 3.5GW, total supply 36.7GW. Over the day wind averaged 1.9GW; the 2020 average was 7.8GW (25%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
Thu 1 Oct, 17:30 (London's peak): wind 1.5GW (4% of supply), solar 0.6GW, gas 20.3GW (54%), imports 3.3GW, total supply 37.6GW. Over the day wind averaged 3.4GW; the 2020 average was 7.8GW (25%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
Wind was less than half its yearly average at the peak on Tue 29 Sep and Thu 1 Oct (2.2GW and 1.5GW, against 7.8GW for the year), so gas made up the gap. (inference from NESO data)
The peak came in the early evening on Tue 29 Sep and Thu 1 Oct, when demand is highest and there is no solar. (inference)
Elexon market index: Tue 29 Sep averaged £60.00/MWh with a high of £100.01 at 07:30; Thu 1 Oct averaged £42.07/MWh with a high of £66.97 at 17:30. Source: Elexon market index, Tue 29 Sep. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)

Storm Alex (Fri 2 Oct to Sun 4 Oct) was within a few days of it. Source: Met Office, UK storm season 2020/21. (confirmed by source; its effect on these prices is inference)

Medium. The grid figures fit the prices, but no report found names a cause for this date.

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.

Tuesday 29 Sep 2020 · half-hourly prices

South Eastern England

7.4p

Cheapest half-hour 2.30am – 3am

35.0p

Dearest half-hour 6pm – 6.30pm

0 hours

Negative prices none on 29 Sep 2020

7.9p avg

Cheapest 3 hours 1am – 4am

14.4p

Average price on 29 Sep 2020

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