According to the price observatory of the French startup Storio Energy, the French electricity market recorded a negative spot price of -€498/MWh on May 1.
The record low was recorded at 1:00 PM and was followed by -€471/MWh at 2:00 PM. This is attributed to low consumption associated with the holiday, combined with reduced flexibility in the nuclear fleet, a phenomenon also observed in April.
For comparison: the lowest price on May 1, 2025 was -€118/MWh.
The difference between the most expensive hour and the cheapest hour in France reached €141/MWh in May, a level unprecedented during the month. According to Storio Energy’s analysis, the indicator did not exceed €100/MWh even at the height of the 2022 energy crisis, when the average electricity price was around €200/MWh.
Since the beginning of the year, the French electricity market has recorded almost 450 hours of zero or negative prices, compared to around 320 hours in the same period of 2025.
In May, 80% of days were affected by zero or negative prices, as were almost two-thirds of hourly slots between 1 p.m. and 5 p.m.
Storio Energy’s analysis adds that a 1MW/2MWh battery charged and discharged on average -€8/MWh at €111/MWh in May, which equates to approximately 1.2 cycles per day.
Since the beginning of 2026, the average spread has therefore been €119/MWh, more than double the leveled storage costs. In this context, arbitrage revenues to be achieved by batteries on the spot market have increased by 34% in 2026 compared to the period January to May 2025.
By the end of May 2026, cumulative revenues from a 1 MW/2 MWh battery energy storage system on the spot market had increased by 34% compared to 2025 and 161% compared to 2024.
