France records negative power prices for most of May

France's Storio Energy, which develops energy storage and management solutions for the business-to-business market, has released new figures showing that May 2025 confirmed a trend observed for several months: electricity prices on the French spot market are reaching zero or negative levels.

The company said 90% of days in May recorded a minimum price of zero or below. Only three days escaped this trend, with slightly positive prices averaging no more than €3.50/MWh.

Storio Energy attributed the phenomenon largely to midday solar overproduction that far exceeds demand.

“We are facing a real energy turning point. Consumers still have little or no incentive to shift their consumption to these very advantageous hours,” argued Jean-Yves Stephan, CEO and co-founder of Storio Energy. “This is a historic opportunity for manufacturers who can adapt quickly.”

In May, a six-hour period from 11 a.m. (CEST) to 5 p.m. recorded strictly negative prices on average for the first time. On May 1 at 2 p.m., the spot price reached -€118/MWh, the second-lowest ever recorded on the French market. To better align supply and demand, 11 million of the 14.5 million households with peak/off-peak options – about 40% of all households – will see their off-peak hours shifted during the summer, with up to three hours moved to daytime between 11 a.m. and 5 p.m.

Storio Energy said price volatility is also rising significantly. Since early 2025, the average daily spread between minimum and maximum prices has been €95/MWh. While the average electricity price for May fell to €19/MWh – a level not seen since April and May 2020, during the height of the pandemic – prices remain elevated during certain periods, particularly between 9 p.m. and 11 p.m., when they exceed three times the monthly average.

“This discrepancy reflects the persistence of structural tensions on the network in the evening,” said Storio Energy.