Transmission system operators across Europe are bracing for the total solar eclipse that will sweep across swathes of Europe on Wednesday and is forecast to cut solar PV output by up to 9.7 gigawatts (GW).
The August 12 solar eclipse will occur during the early evening and will sweep across Greenland, Iceland, northern Russia, the Atlantic Ocean, Spain, and a small corner of Portugal, according to NASA. A partial eclipse will be visible across much of the rest of the European continent.
As with any eclipse, its timing has been known well in advance, giving Europe’s transmission system operators (TSOs) time to prepare for the sudden drop in solar irradiance and generation. In 2025, a solar eclipse accounted for 13 per cent of generation across the European Union.
According to the European Network of Transmission System Operators for Electricity (ENTSO-E), assuming clear skies during the eclipse, solar PV output across Europe could decrease by up to 9.7 GW creating what the organisation describes as “a rapid but predictable change in generation patterns between 19:15-21:30 CEST.”
However, thanks to “well-established coordination mechanisms and proactive preparations”, both ENTSO-E and the continent’s TSOs have long been prepared for the event. So as to ensure continued system operation during the eclipse, TSOs across Europe have implemented a “range of coordinated measures” including heightened awareness in control rooms and shared information with market participants.
Spain and Germany are likely to experience the greatest impact on their systems, based on their respective levels of solar generation.
Spanish grid operator Red Eléctrica expects up to 5 GW of capacity to be lost – which represents around “13 per cent of peak demand for a typical Wednesday in August”, though the final impact will depend on the day’s weather conditions.
Germany’s TSOs jointly predict that up to 2 GW of solar capacity will be lost under cloudless skies, though they confirmed that it will not affect overall electricity supply.
In France, local TSO RTE predicts solar PV production to decrease by around 1.8 GW.
The UK’s TSO, National Energy System Operator (NESO), echoed the preparedness of their Continental peers. Julian Leslie, NESO chief engineer, told the Express, “Like all weather events, Wednesday’s solar eclipse is something we’ve been planning and are fully prepared for. So as millions of Britons drop what they’re doing and head outside to enjoy the spectacle, our control room will be expertly managing the network ready for when they return to their usual routines.”
According to Leslie, the drip in British solar generation only represents a “drop in the ocean” for the overall system.
Nevertheless, British energy gentailer Octopus Energy is running an “Eclipse Power Down” during which the company is asking households to cut back on electricity when the eclipse is at its darkest and solar generation takes its biggest hit.
Those eligible customers who do “use a little less electricity than normal during those two hours” will earn an hour of free electricity on Sunday 16 August. Octopus Energy is also running an eclipse photo competition with the chance to win free solar panels and installation, or £12,000 in cash instead.
Joshua S Hill
Joshua S. Hill is a Melbourne-based journalist who has been writing about climate change, clean technology, and electric vehicles for over 15 years. He has been reporting on electric vehicles and clean technologies for Renew Economy and The Driven since 2012. His preferred mode of transport is his feet.
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