BESS in France

The French energy mix

The bulk of France’s energy production in the first half of 2024 came from nuclear, as it has for decades, followed by hydro. The gas share is lower than wind and solar, which had upwards momentums of 3% and 5%, respectively, compared to the same period of the previous year. Coal-fired plants contribute only marginally to the energy mix, while new sources of flexibility, especially demand-side and storage, are regarded as priorities for the future and to facilitate the integration of more renewables. According to Montel, the French grid operator estimates grid-scale BESS (battery energy storage system) capacities to reach 6 GW by 2030, while Aurora Energy Research forecasts an almost tenfold increase, from approximately 1 GW in 2024 to 9 GW by 2030.

Source: RTE, Electricity System Review, July 2024

The French grid operator

The French transmission system operator (TSO), in charge of the high-voltage public electricity transmission network in France, is locally known as réseau de transport d’electricité (RTE). Responsibilities include:

• Ensuring the balance between production and consumption on French territory in Europe at all times
• Ensuring the safe operation of the electricity system and preventing blackouts (both localized and generalized)
• Guaranteeing good quality standards for electricity (e.g., voltage, frequency, continuity of service)
• Developing and securing the network in line with demand and environmental impact
• Optimizing the electricity market design on a national and continental level

Grid challenges in France

With the French grid running primarily on nuclear, adding large volumes of solar energy leads to midday overproduction that the grid struggles to accommodate, according to Montel. This results in low prices and negative hours, as well as curtailments. Why does this happen? Electrification (EVs, electrolyzers, heat pumps), which could absorb the oversupply to an extent, is progressing slowly in France, and with nowhere to go, the excess energy causes congestion.

According to this report from November 2024, most of France’s new generation in the future is expected to come from PV and offshore wind, with the official pipeline targeting 75-100 GW of solar and 18 GW of offshore wind by 2035. At the same time, little to no new additional hydro or nuclear power is planned, which means variability in the system will inevitably rise. Flexibility can manage these fluctuations, and France is reacting by ramping up BESS and demand response capacities.

In 2024, RTE started easing grid connection rules by offering flexible and low-cost access options for generation and storage. So-called “gabarits” were introduced to expedite the grid connection process for storage projects that accept predefined operating limits without remuneration (e.g., no discharging between 10:00-15:00 from April to September). The TSO has a direct influence on the power generation of electricity producers they have contracts with. This automated, demand-driven process is subdivided into:

• Frequency Containment Reserve (FCR, R1, primary control reserve)
• Automatic Frequency Restoration Reserve (aFRR, R2, secondary control reserve)
• Manual Frequency Restoration Reserve (mFRR, R3, tertiary control reserve)
• Replacement Reserve (RR)

The tables below provide an overview of the available revenue streams in ancillary services, including products and bidding systems.

Ancillary services in France

FCR and aFRR capacity products

FCR is procured through the pan-European internal common market FCR Cooperation. RTE connected to PICASSO, the pan-European platform for cross-border aFRR exchange, in April 2025 to comply with EU balancing rules and enable aFRR imports and exports with the rest of the continent.

The aFRR requirement is measured on a biannual basis, with one value set for the summer semester (April-September) and one value set for the winter semester (October-March). For indivisible bids, the proposed power volume must be less than the maximum threshold of 80 MW.

aFRR energy bids

Applications to place energy bids can be submitted through the TOPNIVEAU platform from D-7 to D-1 by 16:30. Intraday updates are allowed up to 25 minutes before the validity period. Reserve providers can place up to 3 bids in each direction for a validity period, and the offered capacity must not exceed the provider’s certified capacity. For clearing, the volume in the final dispatch schedule is the one that counts in the merit order. The price per MW is calculated every four seconds and differentiated by direction, upward or downward.

mFRR and RR

Although mFRR and RR aren’t common markets for BESS, storage can provide manual balancing under RTE, assuming all certification and contractual requirements are met. Additionally, the battery must comply with technical criteria, such as lead time of activation, telemetry and observability, availability, and minimal duration as specified in RTE procurement and market activation rules.

However, given the current market reality in France, most batteries are first targeting the primary and secondary reserves (FCR and aFRR), as these segments have clearer processes and offer more opportunities for revenue capture. Similar to other European markets, the combination of ancillary services and wholesale (intraday continuous) is the most profitable strategy for BESS optimization in France.

Capacity mechanism

Starting in late 2026, France will employ a capacity mechanism to ensure sufficient availability of electricity during periods of high demand, particularly in winter. Power plants and demand-response providers commit to power volumes they can reliably supply, which are certified by the grid operator with so-called capacity guarantees. Suppliers then acquire as many of these guarantees as needed to make sure their customers are covered during peak demand.

Wholesale market

In the wholesale market, transactions may be purely financial or entail physical delivery of electricity via the French power network. Products can be traded:

• on exchanges
• on OTC (over-the-counter) basis with an intermediary (broker)
• on direct OTC basis without an intermediary (bilaterial trade)

Source: TenneT

Wholesale timeframes and sub-market structures

Imbalance market

The imbalance market in France was created to hold Balancing Responsible Parties (BRPs) accountable for mismatched injection/extraction schedules. RTE settles the deviations every 15 minutes according to the Imbalance Settlement Price (ISP), using a dedicated cost factor to encourage BRPs to stay in balance. The so-called k-coefficient reduces gains for imbalances in the right direction, even if they benefit the grid, and penalizes imbalances in the wrong direction for system aggravation.

Regulations and RTE taxes

In French legislation, the Energy Regulatory Commission (CRE), an independent regulatory body, is responsible for ensuring market functionality. It proposes the rates for access to the transmission and distribution systems, which are subject to the approval of the Ministry of the Economy, Finance and Industrial and Digital Sovereignty. Public electricity transportation is financed through a charge known as Public Transmission User Tariff (TURPE), France’s version of grid fees, which represents around 7.5% of the domestic customer’s energy bill. Industries can use a CRE-provided online calculator to calculate the estimated grid fee amounts for their power injection and withdrawal volumes. Grid fees for storage depend on whether the site is classified as production, injection, withdrawal, or hybrid. In many cases, BESS avoids the double payment.

Grid fee optimization

Grid fees impact the financial outcome of a trading strategy and have a direct influence on the marginal value of charging and discharging a battery at different times across varying grid zones. Integrating TURPE charges into the optimization process captures a more accurate portrayal of temporal and locational costs, improves forecast precision, and ultimately maximizes profitability in line with the French market structure.

Outlook for BESS

Source: Clean Horizon

Clean Horizon’s storage index shows high revenue potential for storage in 2025, noticeably for July, which was a notoriously challenging month for BESS in Germany. Given current market signals and the lack of saturation, 2026 is shaping up to be a promising year for BESS in France.

Disclaimer: The header visual was generated using AI. 

Sources:

RTE - Electricity System Review, July 2024
RTE - Balancing capacities
ENTSOE
RTE - Imbalance settlement price
Ministère Chargé de l'Énergie
Clean Horizon - Storage Index
RTE - Capacity mechanism
TenneT