European solar plants generated 52 TWh in June and then reached a record 55 TWh in July. Solar output covered roughly one-quarter of electricity consumption in both months. The figures came during a summer period marked by extreme temperatures across parts of Europe.
Heatwave demand and drought-linked constraints
Temperatures exceeded 40C, increasing air-conditioning demand while worsening hydrological conditions. Drought constrained generation from water sources during the same period. Hydropower production between May and July fell to its lowest level for that three-month window in at least a decade.
Nuclear generation was also affected by high temperatures and low river flows. Both reactors at Romania’s Cernavoda nuclear plant were taken offline as Danube levels fell. In Hungary, output at Paks was reduced, and several units were temporarily shut.
Nuclear outages and unavailable capacity in France
France faced around 29 GW of unavailable nuclear capacity on 12 July. Scheduled maintenance accounted for much of the total. Environmental restrictions and forced outages were estimated to have affected as much as 11 GW.
Electricity prices tighten as solar fades after sunset
Wholesale prices moved quickly as the balance tightened during heatwave periods in late June and early July. Average Hungarian electricity prices were 119% higher than comparable days in the previous week. France rose 44%, Italy increased 13%, and Spain climbed 7%.
Solar generation reduced daytime scarcity, but system conditions tightened after sunset. Prices rose sharply during early evening hours as photovoltaic output disappeared while cooling demand stayed elevated. The shift highlighted the value of resources that can cover the evening transition when renewable output declines fastest.
The summer also pointed to a growing flexibility challenge for European power systems. Solar increasingly protects the midday market from scarcity, while storage, hydro, and other dispatchable capacity become more important later in the day. This pattern aligned with the observed timing of price increases after sunset during the heatwave period.
