UK grid operator NESO issues fresh power warning amid heatwave

Britain’s National Energy System Operator (NESO) issued an electricity‑margin notice for Friday 7 p.m.–10 p.m., asking generators to provide an additional 700 MW to cover a predicted shortfall. It is the second such request this week after a similar notice for Wednesday was withdrawn on Tuesday afternoon when the operator said supply was secure.

The calls come as a heatwave pushes daytime temperatures to a record‑breaking 36.7 °C in Merryfield, Somerset, prompting rare red extreme‑heat warnings. High heat reduces the efficiency of solar panels and restricts output from nuclear and gas plants, while wind generation was weak.

To meet demand, NESO paid about £11 million on Tuesday to ensure gas supplied the grid – more than five times the usual daily amount – and secured roughly 1.7 GW of electricity imports from Europe at prices as high as £1,400 per megawatt‑hour. Battery services also helped balance the system.

NESO stressed the notice is a routine tool and does not mean supply is at risk, but the episode highlights the strain on Britain’s increasingly weather‑dependent electricity system during intense summer heat.