Britain’s grid operator calls for more electricity as temperatures soar
Extreme heat increases demand for power and reduces efficiency of solar panels
Britain’s grid operator has issued a call for more electricity supplies as extreme heat pushes up demand for power and reduces the efficiency of solar panels and gas-fired power stations.
As the UK’s Met Office issued a red alert for extreme heat for only the second time in its history, the National Energy System Operator (Neso) urged any power stations able to produce more electricity to come forward to help cope with the high temperatures combined with low winds, which have reduced output from wind turbines.
The “electricity margin notice”, covering supply between 7pm and 10pm on Wednesday evening, is the first Neso has issued since January 2025 and the first during the summer.
Neso is in charge of making sure electricity supply and demand is constantly balanced, intervening to smooth out any mismatches in the wholesale market by paying generators to produce more or less electricity.
It operates the system with a buffer between demand and supply, and said the notice reflected its need for a “greater safety cushion between power demand and available supply” rather than imminent power cuts.
While the heat means people are using more power for air conditioning and fans, both gas-fired power stations and solar farms are also less efficient. For every one degree that panel temperatures rise above 25C, solar panels’ efficiency drops 0.3 per cent to 0.5 per cent, according to analysts at Montel.
Gas-fired power plants are less efficient in the heat as warmer air is less dense, meaning they can take in less fuel as the two have to be kept in proportion and they have to work harder to meet required air pressure.
Power prices climbed on Tuesday as winds dropped and temperatures rose across Europe.
The Met Office’s extreme heat alert covers parts of the south of England and Wales on Wednesday and Thursday with temperatures expected to reach 38C to 40C in some places — well above seasonal norms and potentially breaking June records.
Hundreds of trains across the UK have been cancelled as rail companies warned passengers to avoid travelling. Rail operators cancelled services pre-emptively to prevent more severe disruption later in the day.
“Extreme heat can cause rails to expand and buckle, so when temperatures reach certain thresholds, trains must run more slowly to keep services safe,” said London Northwestern.
Avanti West Coast has cancelled more than half of its services, according to live figures from data aggregator trains.im, while Northern, Great Western and South Western have axed dozens of trains. Close to 250 services across the UK have already been cancelled, 7 per cent of the day’s expected journeys, its data showed.
To free up space on faster rail lines, some train companies are switching from non-stop services to slower stopping ones where there are alternatives.
“We encourage customers to think about their comfort and to consider whether their journey is necessary, said Claire Mann, head of operations at Transport for London. “We will do our best to run as many rail and Tube services as possible and keep customers as comfortable as possible.”