July heat raised Czech electricity prices. Solar hit record output

The average electricity price on the Czech day-ahead market reached nearly 110 EUR/MWh in July, around 22% higher year on year. Prices rose despite record output from solar power plants and significantly higher generation at nuclear power plants, while electricity consumption remained virtually at last year's level. This follows from data available on Energostat.

The average spot electricity price in July was the highest since 2022, when the market was significantly affected by the European energy crisis. Compared with July last year, it increased by nearly 20 EUR/MWh, while it was more than 40 EUR/MWh higher than in 2024.

Domestic electricity consumption reached 4.70 TWh in July, only around 10 GWh more than in the same month of 2025. Alongside high temperatures, prices were therefore likely driven primarily by regional conditions, limited availability of dispatchable sources and higher natural gas prices, which feed into the costs of gas-fired power plants.

Similar developments were already evident in June, when a combination of weaker wind power generation in Germany, an evening drop in solar generation and constraints on nuclear sources led to exceptional intraday prices across Europe. In Germany, prices climbed to as much as 868 EUR/MWh in the evening, while prices on the Czech market approached 700 EUR/MWh.

Solar sets new record, nuclear output rises sharply

Total electricity generation in the Czech Republic reached 5.90 TWh in July, approximately 623 GWh higher year on year. The increase in generation thus significantly exceeded the change in domestic consumption, pointing to the greater importance of cross-border trading amid tighter price conditions in the region.

Solar power plants supplied 704.7 GWh of electricity to the grid, surpassing the previous monthly record of 701 GWh recorded in May this year. Compared with July last year, their generation increased by nearly 149 GWh, or around 27%. The result confirms the continued growing importance of photovoltaics in the summer generation mix, but also widens the gap between cheaper midday hours and more expensive evening peaks.

The year-on-year increase in nuclear power generation was even more pronounced. Nuclear plants generated 2.75 TWh in July, compared with 2.16 TWh in the same month of 2025, representing an increase of nearly 594 GWh. Lignite-fired power plants, by contrast, reduced their output from 1.58 TWh to 1.43 TWh, while generation from gas-fired sources fell by around 49 GWh to 246 GWh.

Heat also complicates the operation of gas-fired power plants

This summer has also shown that the risk associated with power plant cooling does not apply only to nuclear units. France's EDF warned in July of the risk of reduced output at the 930 MW Martigues gas-fired power plant, where high Mediterranean Sea temperatures limited the availability of cooling water.

In France, 4.9 GW of nuclear capacity was also constrained during the same period due to high river temperatures, with a further 2.5 GW affected by low water levels. EDF therefore obtained an exemption allowing the Martigues plant to operate even at water temperatures above the usual 30 °C limit, with the new threshold set at 32 °C.

Czechia has different operating conditions, but not market isolation

The Czech Dukovany and Temelín nuclear power plants use closed cooling systems with cooling towers and draw water from the Dalešice, Mohelno and Hněvkovice reservoirs, limiting their short-term dependence on river flows. The direct operational risk from drought is therefore lower than, for example, at once-through cooled power plants on the Danube.

However, the Czech market remains exposed to regional price movements through interconnections with Germany, Poland, Austria and Slovakia. July's developments therefore again underscore the need for faster development of storage, demand flexibility and dispatchable sources capable of responding to increasingly pronounced differences between generation and demand over the course of the day.