But where these sources faltered, solar shone through. European heat waves tend to deliver optimal conditions for solar power: clear, sunny days. Europe’s solar panels produced 17% more power during the summer’s heat waves than they normally do, stabilizing the grid as afternoon cooling demand climbed, according to Ember. Battery systems helped deliver this solar power into the evening hours, when heat still lingered and air conditioners cranked to allow households to sleep.
“The next challenge is the evening period. Temperatures often remain high after sunset and AC demand can stay elevated, even as solar production declines,” said Walburga Hemetsberger, CEO of SolarPower Europe, an industry group. “This is why battery storage is becoming such an important part of the energy transition.”
For as much as this summer’s extreme heat strained Europe’s grid, the continent’s cooling demand has a lot of room to grow: About half of households in Italy and Spain have air conditioning, and a quarter in France — compared with 90% in the United States.
“There are places where we just can’t do without it now,” Marine Tondelier, national secretary of the Ecologist Party, said this June, a reversal in the party’s long-standing argument against air conditioning because of its greenhouse gas emissions.
France’s state-owned utility plans to spend over $10 billion to adapt its nuclear and hydropower plants to warmer temperatures and lower water availability over the next 15 years, including investments in equipment that cools the water nuclear plants discharge into rivers so that it complies with environmental standards. But adapting to that new demand could also take new generation and storage, especially as grids simultaneously increase demand from data centers.
Solar and batteries have already been growing at a breakneck pace across Europe, with 36 gigawatt-hours installed in 2025, a 48% increase over new additions the previous year. Battery installations saw their 12th straight year of growth in 2025, according to industry group SolarPower Europe.
“Extreme price spikes during heat waves are a blaring signal for regulatory changes that increase power system flexibility,” said Beatrice Petrovich, a senior energy analyst covering Europe at Ember. “Treating this summer as a turning point for energy storage would be an opportunity to remove existing barriers.”
