Solar power output surged by up to 17 per cent during this summer's heatwaves, helping European grids meet electricity demand that jumped by as much as 28 per cent in Italy as temperatures soared, according to new analysis from energy think-tank Ember. The findings underscore solar's growing role in Europe's energy mix — but also expose a critical vulnerability after sundown, when cooling demand remains high but panels go dark.
Demand Spike Hits Southern Europe Hardest
During the late-June heatwave this summer, daily electricity demand rose 28 per cent in Italy, 23 per cent in Hungary, 14 per cent in France and 13 per cent in Spain compared with pre-heatwave days. Heatwaves trigger sudden spikes in consumption because of energy-intensive air conditioning units. The International Energy Agency estimates that space cooling — mostly air conditioning units and fans — consumed around seven per cent of the world's electricity in 2022. Even in countries where air conditioning ownership is low, scorching temperatures drive demand upward. During the early summer heatwaves last year, France recorded an evening electricity peak that was 25 per cent above the off-season average.
Ember's analysis found that solar was the only major power source to perform better than usual as heatwave-driven demand increased. Compared with other days in June and July, average daily solar generation during the heatwaves was 17 per cent higher in France and Hungary, five per cent higher in Spain and the same in Italy. Researchers said the extra generation helped power the grid as electricity demand increased by as much as a quarter on hot days.
Evening Gap Exposes Grid to Gas Prices
Senior energy analyst Chris Rosslowe said, "Solar is already doing heavy lifting during heatwaves, but the real challenge starts after sundown." He said, "In the evening, when cooling demand is still high, the grid is most exposed to expensive gas-fired power."
The late-June and early-July heatwaves this summer saw average daily electricity prices surge 119 per cent higher in Hungary, 44 per cent in France, 13 per cent in Italy and seven per cent in Spain than on comparable days in the preceding weeks. The price surge underlined the need for battery storage systems, which can prevent excess solar energy from being wasted.
Climate Stress Hits Nuclear and Hydro
Europe's back-to-back heatwaves, which scientists say would have been virtually impossible if it weren't for climate change, have triggered mass droughts across the continent. Low water levels along the Danube River forced nuclear output to be curtailed in Hungary, while experts warned that hydropower neared an all-time low in the Alpine region. Fossil-fuelled energy has also suffered from the drought, with Poland forced to reduce output at a coal-fired power plant because of critically low water levels in the Vistula River.
Rosslowe said, "While solar saves the day, battery storage can save the evening." He added, "Together, they are one of the clearest ways to make Europe's power system more resilient in the hotter summers. As solar output rises during heatwaves and other power sources struggle, storage can carry that cheap electricity into the evening."
Why This Matters:
Europe's energy security depends on diversification — and this summer's heatwaves showed both the promise and the limits of solar power. Solar helped meet surging demand without relying on expensive gas imports, but the evening gap remains a fiscal and reliability problem. Electricity prices more than doubled in Hungary when the sun went down and cooling demand persisted. Battery storage isn't a luxury; it's infrastructure that prevents European households and businesses from being gouged by volatile gas markets. The competitiveness of European industry depends on stable, affordable electricity. If Europe can't store the solar power it generates during the day, it'll keep paying premium prices for gas every evening — and that's a subsidy to foreign suppliers, not a path to energy independence.