Negative prices (Agile’s first ever negative price)
Research notes
Figures are for London unless they say otherwise.
What happened
- Sat 8 Dec: London was below zero for 1.5 hours from 03:30, min −2.3p at 04:30; average 11.8p, peak 30.4p at 16:30; all 14 regions at 0p or below; lowest −2.8p in Northern Scotland.
Likely causes
- Octopus said this was the first time Agile paid customers to use electricity: "On Saturday 8th December, British consumers were paid to use electricity", "PAID 2.31p per kWh" at the lowest point between 3.30am and 5.30am, after a "bumper day of wind generation". Source: Octopus Energy, 11 Dec 2018. (confirmed by source)
- Sat 8 Dec, 04:30 (London's lowest half-hour): wind 12.5GW (48% of supply), solar 0GW, gas 3.8GW (14%), imports 1.4GW, total supply 26.3GW. Over the day wind averaged 11.9GW; the 2018 average was 5.8GW (17%). Source: NESO historic generation mix. (figures confirmed by source; link to prices is inference)
- Wind was well above its yearly average at the lowest half-hour on Sat 8 Dec (12.5GW, against 5.8GW for the year). (inference from NESO data)
- The low came overnight on Sat 8 Dec, when demand is at its lowest (total supply as low as 26.3GW, against a 2018 average of 34.1GW). (inference)
- Sat 8 Dec was at the weekend, when demand is lower. (inference)
- Elexon market index: Sat 8 Dec averaged £42.84/MWh with a low of −£8.69 at 00:00. Source: Elexon market index, Sat 8 Dec. (confirmed by source; a short-term index, not the day-ahead auction Agile follows)
Wider context that week
- Storm Deirdre followed a week later, on 15 and 16 Dec 2018. Source: Met Office, UK storm season 2018/19.
Confidence
High. Octopus’s own announcement names the date, the price and the wind.
Gaps
- Elexon's system warnings feed has no entries before mid-2023, so warnings for these days couldn't be checked there.