Transmission System Operators prepare for solar eclipse to ensure secure system operation

On 12 August, a solar eclipse will temporarily reduce solar power generation across large parts of Europe as the Moon passes in front of the Sun. Under clear-sky conditions, photovoltaic (PV) output could decrease by up to 9.7 GW across Europe, creating a rapid but predictable change in generation patterns between 19:15-21:30 CEST. Thanks to well-established coordination mechanisms and proactive preparations, ENTSO-E and Europe's Transmission System Operators (TSOs) are ready to ensure the secure and stable operation of the electricity system throughout the event.

Solar energy has become an essential component of Europe's electricity mix, accounting for approximately 13% of EU electricity generation in 2025. As renewable energy sources continue to grow, TSOs are increasingly managing weather-related and natural phenomena that can influence generation patterns over short periods of time.

What proactive measures have TSOs taken to maintain stability?

To maintain secure system operation during the eclipse, TSOs across Europe have implemented a range of coordinated measures. Control room operators have been briefed in advance to ensure heightened awareness, while market participants have received information on the expected reduction in solar generation. Spain and Germany are expected to experience the highest impact (based on the expected decrease in PV production). To support real-time decision-making, local system operators receive additional updated photovoltaic generation forecasts from weather service providers.

In addition, TSOs are avoiding planned grid outages during the eclipse period to maximise operational flexibility. ENTSO-E has also activated a dedicated task force to coordinate preparations, monitor developments and facilitate information exchange among TSOs before and after the event.

As Europe continues its energy transition, the ability to anticipate and respond to short-term fluctuations in renewable generation remains a key element of maintaining a secure, reliable and efficient electricity system. With careful planning and coordination, this solar eclipse provides an opportunity to demonstrate the preparedness and adaptability of Europe's electricity sector.