IN Brief:
- Ten operational sites add 57MW/114MWh of battery storage to France's distribution network.
- Entech delivered the EPC scope using CATL battery pods and SMA inverters.
- COMAX France now operates more than 86MW/143MWh as France's battery connection pipeline continues to expand.
COMAX France has completed a 57MW/114MWh battery energy storage portfolio across ten sites connected to France’s distribution network, increasing its operational battery fleet in the country to more than 86MW/143MWh. The sites were developed over three years and are now fully operational.
Entech was responsible for the engineering, procurement, and construction scope, with CATL battery pods and SMA inverters used across the portfolio. The ratio between power and stored energy gives the new capacity a nominal duration of two hours, placing it firmly within the short-duration flexibility market rather than long-duration bulk energy storage.
The projects form part of MET Group’s expansion in flexible electricity assets following its acquisition of COMAX, which already operated generation and battery capacity in France. Adding ten separate storage sites changes the scale of the fleet without concentrating all of the new capacity behind one grid connection, giving the operator a geographically distributed set of assets rather than a single utility-scale installation.
That distinction affects both engineering and operation. Each connection has its own local network conditions, protection requirements, metering, communications, and availability profile, while the portfolio as a whole can be optimised across several electricity-market opportunities. Maintaining reliable telemetry and dispatch across ten sites becomes as important as the performance of the battery containers themselves.
France’s battery market remains smaller than its development pipeline suggests. RTE recorded 1.6GW of battery storage in service at the end of 2025, with roughly one third connected to the transmission network and most of the remainder connected to distribution systems. Projects that had already secured grid access amounted to around 14GW, although RTE cautioned that many had not reached final investment decision.
The difference between operating capacity and the connection queue is significant for new storage owners. Today’s batteries can participate in a market with comparatively limited installed competition, but the economics will change as larger projects reach commissioning and additional capacity competes for balancing, reserve, and wholesale opportunities. Connection status alone is therefore a poor guide to how quickly the operating fleet will grow.
The COMAX sites sit in the part of the market where distribution-connected storage can respond quickly without requiring a transmission-scale connection. Batteries can absorb electricity when prices or system conditions favour charging and return it when demand or prices rise, while suitable assets can also participate in reserve and balancing services. Their useful contribution still depends on local network limits, market access, and the accuracy of the control systems managing state of charge and dispatch.
The equipment selected for the portfolio illustrates the division of functions inside a modern BESS. CATL’s battery systems provide the electrochemical storage, while SMA inverters convert DC battery output to AC for the network and control the flow of active and reactive power. Those power electronics also have to operate within connection requirements governing voltage, frequency behaviour, protection, and response to grid events.
Two-hour systems are increasingly common because they can cover a wide range of short-duration services without carrying the capital cost of four, six, or eight hours of stored energy. The trade-off is that an asset delivering its full rated output exhausts its available energy relatively quickly, so dispatch strategy has to consider which intervals justify using limited stored energy and how much headroom should be retained for later opportunities.
Battery degradation adds another constraint. Repeated charging and discharging gradually changes usable cell capacity and performance, while temperature, depth of discharge, and operating rate influence the speed of ageing. Owners therefore have to balance short-term market revenues against warranty limits, long-term capacity retention, and the cost of eventual augmentation or component replacement.
With the ten sites commissioned, COMAX has moved from construction risk into portfolio operation. The question now is not whether the batteries can be connected, but how consistently they can be kept available and dispatched as France’s storage fleet grows. A connection pipeline approaching 14GW leaves considerable room for expansion, but it also points towards a market in which operating discipline will carry more weight than another headline capacity figure.
