Entech Secures 45M Dollar EPC Contract for 90 kV Substation and 90 MW Battery in France

High-voltage grid connections for utility-scale battery energy storage systems are increasingly shifting from distribution networks to transmission systems. The award of an EPC contract valued at nearly 40 million euros, approximately 45 million dollars, for a 90 MW and 180 MWh battery installation in France illustrates this transition. Connecting directly to the transmission network at 90 kV under the oversight of transmission system operator RTE, the facility highlights how large-scale balancing assets must interface directly with high-voltage infrastructure.

For substation engineers and asset managers, transmission-connected battery storage introduces operational dynamics distinct from conventional generation or standalone solar and wind assets. Battery installations can shift from full discharge to full charge almost instantaneously. This bidirectional duty subjects substation transformers to intense thermal cycling and distinct loading profiles that diverge from steady-state baseload or predictable solar bell curves. Inverter harmonics, repeated switching operations, and rapid voltage flux demand robust transformer design, in line with rigorous thermal and mechanical withstand criteria.

Furthermore, protection relays and switchgear must accommodate fast-acting fault currents and bidirectional power flow without unintended tripping. Substation control schemes interfacing with transmission systems must coordinate closely with the system operator to preserve network stability during rapid frequency response activations.

What this means for asset owners in Europe: Transmission-connected energy storage developments in France and neighbouring networks underline the need to evaluate transformer life consumption and thermal stress under severe cyclic loading. Plant operators and network planners procuring substations for fast-acting assets must specify transformer thermal performance and bidirectional protection schemes, while anticipating extended procurement lead times for high-voltage switchgear and power transformers during early planning stages to prevent commissioning delays.