The 12 August total solar eclipse is forecast to reduce European photovoltaic generation by as much as 9.7 GW under clear-sky conditions. The strongest physical impact is expected over Iberia, France, the United Kingdom and Italy. Because electricity markets are interconnected, the effects are also expected to extend into Central and Southeast Europe.
Eclipse timing and implications for the evening ramp
The eclipse is expected to occur relatively late in the day, when solar output is already declining. As a result, the overall energy loss is expected to be smaller than it would be around midday. The event could still increase the speed of the solar decline during a period when power systems are already ramping thermal generation for the evening.
Central Europe and Balkans: indirect effects on cross-border flows
In Central Europe and the Balkans, the impact is described as primarily indirect but commercially significant. Lower domestic solar output in Italy and France could reduce electricity available for exports toward Slovenia, Croatia and the wider Adriatic region. Germany is also expected to provide less surplus generation, with wind output falling to around 4.7 GW, or about 60% below seasonal levels.
Nuclear constraints and day-ahead price moves in France and Germany
France’s day-ahead electricity price rose to €142.50/MWh, while Germany reached €138.50/MWh. High temperatures are cited as constraining nuclear availability, alongside weaker wind reducing renewable generation. French nuclear limitations could affect up to 7.3 GW, equivalent to around 12% of the country’s reactor fleet.
UK margin notice and price reaction during eclipse evening
In Britain, the system operator issued a margin notice for the eclipse-period evening. The initial estimate pointed to a supply shortfall of more than 1.7 GW, before being revised to approximately 1.2 GW. British evening electricity prices then moved above £211/MWh.
Although the UK is outside the Southeast European trading system, the warning is described as highlighting broader European competition for flexible generation during the same hours.
Forecast uncertainty and balancing risks across markets
European system operators have been preparing for the eclipse for months, which is expected to make it less dangerous than an unexpected outage of comparable size. The main trading risk is described as stemming from how the eclipse interacts with forecast uncertainty. Factors such as higher cooling demand, an additional nuclear outage, weaker-than-expected wind generation or delayed battery availability could increase balancing costs.
Southeast Europe: potential driver of evening price volatility
For Southeast Europe, the eclipse is described as another potential source of evening price volatility. The region increasingly depends on cross-border flows and flexible generation to manage the gap between midday renewable surpluses and evening demand.
