European Heatwaves Push Electricity Demand Up 28%; Solar Output Climbs 17% in France and Hungary, Ember Finds

Solar generation increased by as much as 17% in several European countries during heatwave days in June and July, helping power grids cope with a sharp rise in electricity demand, according to new analysis by Ember.

The analysis found that daily electricity demand increased by up to 28% in Italy, 23% in Hungary, 14% in France and 13% in Spain during the late-June and July heatwaves compared with pre-heatwave days. Solar was the only major power source to perform better than usual during the extreme heat. Average daily solar generation was 17% higher in France and Hungary, 5% higher in Spain and unchanged in Italy compared with other days in June and July.

“Solar is already doing heavy lifting during heatwaves, but the real challenge starts after sundown,” said Chris Rosslowe, senior energy analyst at Ember. He noted that cooling demand remains high in the evening, increasing the grid’s exposure to expensive gas-fired generation.

Extreme heat and drought also disrupted other major power sources across Europe. Nuclear generation was curtailed in France, Hungary, Romania and Switzerland, while gas and coal plants faced operational constraints linked to high temperatures and low water levels. Hydropower output also remained below five-year averages in seven of the EU’s eight largest producing countries in July.

The supply disruptions contributed to significant increases in electricity prices. During the late-June and early-July heatwaves, average daily prices were 119% higher in Hungary, 44% higher in France, 13% higher in Italy and 7% higher in Spain compared with comparable days in the preceding weeks. Several markets also recorded sharp price spikes during the early evening as solar generation declined while cooling demand remained elevated.