The 12 August total solar eclipse is expected to reduce European photovoltaic generation by as much as 9.7 GW under clear-sky conditions. The strongest physical impact will be concentrated in Iberia, France, the United Kingdom and Italy, but interconnected electricity markets mean the effects will also be felt across Central and Southeast Europe.
The eclipse will occur relatively late in the day, when solar generation is already declining. As a result, the overall loss of energy will be smaller than it would have been around midday. However, the event could sharpen the rate of solar output decline at a critical period when power systems are already increasing thermal generation to cover the evening ramp.
For Central Europe and the Balkans, the impact is primarily indirect but commercially significant. Lower domestic solar output in Italy and France could reduce the amount of electricity available for exports towards Slovenia, Croatia and the wider Adriatic region. Germany is also providing less surplus generation, with wind output falling to around 4.7 GW, approximately 60% below seasonal levels.
France’s day-ahead electricity price rose to €142.50/MWh, while Germany reached €138.50/MWh, as high temperatures constrained nuclear availability and weaker wind reduced renewable generation. French nuclear limitations could affect as much as 7.3 GW, equivalent to around 12% of the country’s reactor fleet.
In Britain, the system operator issued a margin notice for the eclipse-period evening, initially identifying a supply shortfall of more than 1.7 GW before revising the estimate to approximately 1.2 GW. British evening electricity prices subsequently moved above £211/MWh. Although the UK is outside the Southeast European trading system, the warning highlights the broader European competition for flexible generation during the same hours.
European system operators have been preparing for the eclipse for months, making the event less dangerous than an unexpected outage of comparable size. The main trading risk instead comes from the interaction between the eclipse and forecast uncertainty. Higher cooling demand, an additional nuclear outage, weaker-than-expected wind generation or delayed battery availability could turn an anticipated solar decline into a significantly more expensive balancing event.
For Southeast Europe, the eclipse therefore represents another potential source of evening price volatility, particularly as the region increasingly depends on cross-border flows and flexible generation to manage the gap between midday renewable surpluses and evening demand.
