Octopus and UK Power Networks gave free electricity at midday to soak up wasted solar

In 2023, UK Power Networks, which runs the grid in the East of England, London and the South East, and energy supplier Octopus trialled free electricity. Sometimes more solar and wind power is produced in one area than can be used or moved, so generators are ordered, and paid, to shut down. This constraint cost £1.2bn in 2021, ultimately paid through bills, and the BBC reports the government has predicted it could reach £2.5bn a year by the end of the decade.

The "Power-Ups" are announced around a day before the window, for customers in certain postcodes who have pre-registered. On 18 August 2023, a two-hour free window ran on a day when UKPN had asked the 13MW Chisbon solar farm in Essex to power down between 12:00 and 14:00. Octopus said 16,700 customers in the East of England and Kent took part and used four times as much electricity as in the same period the week before.

One participant, Daryl Bradley in Cambridge, set timers on his tumble drier and EV charger and topped up four home batteries. His household used 36kWh that day, 24kWh of it in the free window, without using more overall, and he estimated saving £5 to £6.

Instead of paying generators to stop, announce a free-electricity window a day ahead and pay customers in kind to move demand to when power is plentiful.

Using the surplus locally avoids both turning generators down and building more infrastructure to move the power across the country.

UKPN's innovation director said moving 15% to 20% of demand away from the 17:00 to 21:00 peak makes a significant difference.

A day's notice is enough for people with timers, EVs and batteries to move flexible loads.

Octopus says more efficient use of existing wires, pylons and power stations means less to build and lower bills for everyone.

Shifting demand to the surplus can be cheaper than curtailing supply or building wires: price the flexibility directly and let customers do the shifting.

This was a trial, and the BBC piece asked whether it is fair. A professor at Anglia Ruskin University warned that people on low incomes, with less technical know-how or fixed working patterns, risk being "doubly disadvantaged" because they cannot use the windows as easily. The report does not give the grid-cost saving from the 18 August session.