The electricity system operator (ESO) said on Monday it was looking for bids from suppliers to help save up to 341MW of power between 4.30pm and 6pm on Tuesday.
The “demand flexibility service” had only been used in trials before its first live use – during a “saving session” scheduled for between 5pm-6pm on Monday.
The scheme is only open to businesses and households with a smart meter whose supplier or aggregator is one of the 26 firms to have signed up.
More than 1m households and businesses have signed up to participate and most suppliers have closed the scheme to new participants. The household suppliers include British Gas, E.ON, Octopus Energy and EDF.
Under the initiative, a household’s power use will be compared with their normal usage for that time of day, and they will receive about £3 for every kilowatt hour saved.
Read more at The Guardian