French electricity hits record lows in May: 90% of days see negative prices

May 2025 cemented a remarkable shift in the French wholesale electricity market. The average price fell to 72/MWh, with negative pricing recorded across key hourly slots nearly every day.

According to the Observatoire mensuel des prix de l"électricité by Storio Energy, "the minimum price was zero or negative during 90% of the days in the month.

The lowest price recorded was -118/MWh, highlighting the increasing prevalence of excess generation, particularly during midday hours dominated by solar production.

Weekends saw the typical morning price peak disappear entirely, with only the midday dip intensifyinga stark shift in market dynamics.

Volatility has become a defining feature of the 2025 electricity market. The average monthly spreadthe difference between maximum and minimum pricesremained high, reaching 95/MWh in May, only slightly below April"s peak of 99/MWh.

Compared to 2024, the cumulative spread across January to May 2025 rose by 61%, reflecting the increasing variability driven by intermittent renewables.

This dynamic challenges both suppliers and grid operators in forecasting and balancing supply.

The price profile throughout the day has shifted dramatically. Prices were systematically negative between 11:00 and 17:00, and the traditional 18:00 peak was replaced by a late evening surge around 22:00.

According to Storio Energy, "the average price is negative during that interval", signalling oversupply during solar hours.

This confirms a critical imbalance between renewable generation profiles and consumption curves, intensifying the need for demand flexibility and storage.

Industrial and electro-intensive consumers stand to gain from the new pricing structure. Sectors such as aluminium, steel, glass, data centres and chemicals can realign operations to benefit from ultra-low or negative pricing by shifting energy loads.

As Storio Energy observes, SSimple and optimised energy storage for professionals becomes a clear competitive advantage.

Industries equipped to respond to hourly signals can significantly reduce operating costs while supporting grid stability through flexible demand.

The surge in negative prices enhances the financial case for energy storage systems. Batteries and other flexible assets can be charged when electricity is effectively free, or when the grid pays for its absorption, and later discharged during price peaks.

Storio Energy, a French leader in battery storage for industrial and electro-intensive clients, states, SEnergy storage is no longer an optionit is a prerequisite to capture value in a volatile system.

This model not only improves revenue streams but also supports decarbonisation by enhancing renewable integration.

This new pricing reality demands a regulatory response. The high frequency of negative pricing erodes the financial viability of both conventional peaking plants and newer renewable investments.

Policymakers, led by the Energy Regulatory Commission (CRE), must now consider:

• Introducing flexible markets or revised capacity remuneration mechanisms;

• Promoting dynamic tariffs for industrial and residential consumers;

• Accelerating support for behind-the-meter storage and demand-side management.

Without targeted reforms, investor confidence and long-term system reliability could be jeopardised.

The shift observed in April and May signals a structural evolution in the French power system. In April, negative prices occurred on 80% of the days, increasing to 90% in May㬐18-19⬠Storio Energy Reports.

Midday electricity is now systematically freeor even compensatedand traditional pricing curves are vanishing.

This new electricity market order calls for strategic repositioning by utilities, industrial users, and grid planners alike.

Adapting to this environment is no longer optionalit is essential for competitiveness, resilience and sustainability.