Europe’s power grid faces dual threat from eclipse and heatwave

European grid operators are preparing to manage a dual challenge next week as the August 12 total solar eclipse — the first visible from mainland Europe since 1999 — coincides with heatwave-related shutdowns at thermal and nuclear power plants across the continent.

ENTSO-E, the association representing Europe's 40 transmission system operators across 36 countries, warned that under clear-sky conditions, photovoltaic output could decrease by up to 9.7 gigawatts across Europe during the eclipse window between 7:15 p.m. and 9:30 p.m. CEST on Wednesday. Spain and Germany are expected to experience the largest reductions in solar generation.rte+1

Eclipse Preparations Underway

The operators have activated a dedicated task force to coordinate preparations, monitor developments, and facilitate information exchange before and after the event. Proactive measures include briefing control room operators, warning market participants about the expected dip, and avoiding planned grid outages during the eclipse period to maximize operational flexibility.entsoe+1

Spain's grid operator, Red Eléctrica, has warned the eclipse could reduce solar output in Spain alone by as much as 5 gigawatts, representing approximately 13 percent of maximum generation capacity for a Wednesday. With solar now making up about 13 percent of Europe's overall electricity mix, ENTSO-E said its members are "increasingly managing weather-related and natural phenomena that can influence generation patterns over short periods of time".tradersunion+1

Heatwave Compounds Supply Pressures

The eclipse arrives amid already tight supply conditions driven by extreme heat. In Poland, two major coal-fired power plants have reduced output or shut down generating units due to low water levels in the Vistula River, cutting approximately 1.3 gigawatts of capacity. In France, three nuclear reactors have gone offline because of insufficient river water for cooling.tradersunion

Hydropower reserves are also strained. Norwegian reservoirs, a vital source of electricity exports, are reportedly at their lowest levels in three decades. EDF chief executive Bernard Fontana has indicated the reactor shutdowns will affect the utility's annual profits and announced the company will accelerate an €8.7 billion initiative to adapt nuclear and hydroelectric facilities for higher temperatures.tradersunion

Outlook

While the European Commission has said there are no immediate concerns regarding supply security, a spokesperson described the situation as "tight" and noted officials are closely monitoring weather forecasts. The convergence of a predictable astronomical event with climate-driven infrastructure strain underscores what ENTSO-E called the growing complexity of managing a grid increasingly reliant on weather-dependent generation sources.entsoe+1