Emergency imports added an estimated £11million to electricity bills after Britain turned to Europe for extra power
Britain's electricity grid has been thrown into crisis this week as the ongoing heatwave forced the country to pay extraordinary premiums for emergency power imports from the continent.
On Wednesday evening, the UK shelled out close to £1,400 per megawatt hour for European electricity, roughly 1,600 per cent above typical rates and approximately 15 times normal wholesale prices.
The National Energy System Operator (Neso) scrambled to secure supplies after domestic generation from solar and gas plants fell short of surging demand.
The emergency purchases, totalling up to 2.3 gigawatts primarily sourced from the Netherlands, added an estimated £11million to consumer bills in a single evening.
Neso required special permission from the EU to complete the transaction, as European nations had restricted sales to protect their own supplies during the extreme weather.
The grid operator has now issued a second electricity margin notice this week, warning that supplies could be stretched again on Friday evening.
Neso is calling for an additional 700 megawatts of generating capacity between 7pm and 10pm to provide a buffer against anticipated shortfalls.
A spokesman for the operator said forecasts indicated "tight margins on the electricity system" for Friday evening, attributing the strain to "the impact of extremely high temperatures affecting Great Britain and the continent."
The notice follows Wednesday's emergency, though Neso cancelled that day's warning shortly after 2pm after becoming confident in supply levels.
The spokesman emphasised that such notices are "a routine tool" and do not indicate electricity supply is at risk.
Temperatures reached 36.7C in Somerset on Thursday, provisionally setting a new record for the hottest June day.
Energy consultants have sharply criticised Neso's handling of the crisis, accusing the government body of failing to accurately predict demand.
Noémie Baud from Montel said the operator appeared to have misjudged the surge in electricity consumption by as much as three gigawatts—equivalent to the output of three nuclear power stations.
"Neso appears to have underestimated the amount of offices that we have in the UK," she said.
"The UK now has a lot of shops, industry and businesses, and they all have aircon, so the aircon effect on demand definitely does matter."
Kathryn Porter from Watt Logic was equally critical, stating: "The reality is that Neso failed to anticipate the shortfall due to poor modelling, which meant it was left using extraordinary measures to address it."
She added that frequency fluctuations the previous evening had signalled the grid was under strain, describing Neso's solution as having to "beg" for supplies.
Multiple factors combined to create the supply crunch. Several gas-fired power stations had been taken offline for routine summer maintenance, a practice that Fintan Devenney, senior market analyst at Montel EnAppSys, suggested may need to end given the increasing frequency of heatwaves.
EDF confirmed that four of Britain's ten remaining nuclear reactors were not operating—two undergoing scheduled repairs and two more shut down for unplanned maintenance.
The extreme heat also degraded solar panel performance, according to Lydia Davies from LCP Delta, who explained that panels produce less electricity in very high temperatures.
Nuclear and gas facilities faced their own heat-related challenges, with cooling systems struggling under the conditions.
In France, several nuclear stations relying on river water for cooling had to reduce output or shut down entirely because water temperatures were too high.