A heatwave with local temperatures exceeding 40°C in June and July placed a heavy strain on European power grids. Electricity demand, driven primarily by increased use of air conditioning, caused daily electricity prices to skyrocket. Nevertheless, the grids remained stable, thanks to high levels of solar energy. This is the conclusion of an analysis by the British think tank Ember.
According to the analysis, the heatwave increased daily electricity demand by up to 14 percent. Combined with outages at thermal power plants, this led to a two- to threefold increase in average daily electricity prices. In June 2025, the highest solar power generation ever recorded in the EU was 45 TWh. As a result, the grid was well supplied during the day despite the outages at thermal power plants. The French nuclear power plant fleet was the most severely affected: according to Ember, all but one of the 18 plants had to accept a certain reduction in capacity. At the peak of the heatwave, solar energy alone supplied up to 50 gigawatts (GW) of electricity in Germany, generating 33 to 39 percent of the country’s electricity. Germany has 14 GW of battery storage and 10 GW of pumped storage, which helped to store some of the solar energy for use after sunset.
»Heatwaves will not go away – they will only get more severe in the future. Solutions that can help mitigate their impacts, such as battery storage, interconnection, demand flexibility and dynamic tariffs, should become a key part of grid planning and power market design. Luckily, there is no lack of sunshine during heatwaves. The biggest opportunity is to store solar electricity, to help power air conditioning well into the evening,« said Pawel Czyzak, Ember’s program director for Europe.
© PHOTON
