Eclipse triggers plea for extra power from the grid

Britain’s grid operator has issued a plea for power during the solar eclipse as electricity supplies come under strain.

The National Energy System Operator (Neso) said there would be a shortage of spare capacity between 5pm and 10pm on Wednesday evening.

It has asked energy generators to activate any additional capacity they have, saying the buffer against an electricity shortage is 1,760 megawatts below the desired amount.

Octopus Energy, Britain’s biggest electricity provider, has urged people not to use electricity during the eclipse, which will reach its maximum point at 7.12pm.

Neso said it was a “precautionary measure” because of the event.

“We have used our routine tool of issuing an Electricity Margin Notice (EMN) for tomorrow evening’s peak, which simply means we are asking market participants to make any additional generation capacity they may have available,” a spokesman said.

“The notice has been issued as a precautionary measure to the market due to the solar eclipse, and there is no risk to customer electricity supplies.”

The notice, issued on Tuesday night, is the fourth EMN the grid operator has issued this year. It said it wanted 700 megawatts available as a contingency measure against unexpected problems.

Neso said the measure did not mean that blackouts were imminent.

“An EMN is used to send a signal to the electricity market. It highlights that, in the short-term, we would like a greater safety cushion between power demand and available supply,” the notice said.

“It does not signal that blackouts are imminent or that there is not enough generation to meet current demand.”

The eclipse is expected to cut 95pc of Britain’s sunlight for a brief period, leading to a brief plunge in electricity generated by solar, which accounted for 14.4pc of Britain’s electricity last month.

It will occur during evening peak hours as people return home, turn on their lights and cook meals.

Octopus is encouraging users to switch off by offering them free electricity if they cut their usage during the eclipse.

The eclipse would first be visible in parts of Greenland, Iceland and northern Russia, then enter northwestern Iberia and finish its path over the Balearic Islands at sunset, according to the European Space Agency.

The likely reduction in solar power output is significant but not large relative to overall demand.

The risk comes mainly from the speed with which light levels are expected to fall, which is much faster than in a normal sunset.

It means Neso must respond to changes in light levels much faster than during a normal sunset – with a particular focus on maintaining frequency and voltage stability.

Gas-fired generation will be key to this, as UK hydroelectric resources have been severely affected by drought-related water shortages.

Additionally, three of the UK’s ten nuclear reactors are offline for repairs or refuelling.

Warnings in Europe

Similar warnings are also affecting Europe.

Entso-e, the Brussels-based trade body for European transmission system operators, said that the eclipse could cut Europe-wide solar output by nearly 10 gigawatts (GW) – equal to the capacity of 12 of the UK’s operating nuclear power stations.

This would “create a rapid but predictable change in generation patterns between 19:15-21:30 central European time”.

The biggest impact would be in Spain, where the eclipse could cut up to 5 GW of solar generation, about 13pc of typical demand, national transmission operator Red Eléctrica said.

Meanwhile, Germany’s four high-voltage transmission operators – Amprion, 50Hertz, Tennet and TransnetBW – told Montel analysts that solar generation was expected to fall by up to 2 GW, though this accounted for less than 2pc of total installed capacity.

France’s Réseau de Transport d’Électricité forecast a decrease of about 1.8 GW, or around 5pc of installed capacity.