Heatwave: Solar power helps European electricity grids absorb peak demand

Photovoltaic production helped support several European electricity grids during the heat waves of late June and July 2026. According to a study published Thursday, August 13, by the think tank Ember, solar produced more than usual at a time when demand was increasing and several conventional means of production were affected by heat or drought.

Electricity demand stimulated by cooling needs

During the heat wave at the end of June, daily electricity demand increased by 26% in Hungary, 22% in Italy, 11% in France and 8% in Spain compared to the previous week, according to Ember.

This increase is largely due to the growing use of air conditioning and cooling systems. It comes at a time when high temperatures and drought can simultaneously reduce the availability of several means of production.

Up to 17% more solar production

Among the main electricity sources analyzed, solar was the only one to produce more than on other days in June and July. Daily photovoltaic production increased by 17% in France and Hungary, and by 5% in Spain and Italy, according to data reported by Ember.

This additional production, available during the sunniest hours, helped to meet increased consumption and limit strain on the grid.

"The increase in solar power generation helped stabilize the grid at a time when other energy sources were struggling to operate normally," said Chris Rosslowe, senior analyst at Ember.

Nuclear, gas, coal and hydroelectric power affected

Nuclear power production was disrupted in France, Hungary, Romania, and Switzerland. In Great Britain, five gas-fired power plants reduced their output, while the low level of the Po River in northeastern Italy threatened the operation of thermal power plants.

Coal-fired power plants have also had to limit their production in Serbia and Poland. These facilities depend, in particular, on the availability of water for cooling or for transporting fuel.

Hydropower has also been penalized by the drought. Seven of the eight largest producing countries in the European Union, which together account for 90% of European hydropower production, recorded levels below their average of the last five years.

A sharp rise in electricity prices

The combination of high demand and reduced availability of several means of production has impacted the markets. During the heat waves of late June and early July, average daily electricity prices rose by 119% in Hungary, 44% in France, 13% in Italy, and 7% in Spain compared to previous weeks.

The main price peaks were recorded in the early evening, when photovoltaic production was decreasing while cooling needs remained high.

"The difficulty (with solar energy) begins after sunset," Chris Rosslowe points out. In the evening, when demand remains high, "the network is then very dependent on gas-fired power plants."

Storage to extend the solar energy supply into the evening

For Ember, combining photovoltaics and batteries is one of the solutions to this limitation. The electricity produced during the day can be stored and then fed back into the grid after sunset to reduce the need for thermal power plants during peak evening demand.

However, storage does not replace the other means necessary for balancing the electricity system. Its development must be accompanied by network adaptation, greater demand flexibility, and dispatchable generation capacity available when renewable production decreases.

“Solar energy saves us during the day, but battery storage can save us in the evening. Together, they are one of the cleanest ways to make the European electricity system more robust during the hottest summers,” concludes Chris Rosslowe.