Battery energy storage for grid stabilisation

Eiffage Énergie Systèmes and Entech are working together on the delivery of a battery energy storage system (BESS) and an associated high-voltage substation for an independent solar power producer. The project is designed to support stabilisation services for the French electricity transmission network.

Context of the cooperation
The deployment of battery energy storage systems addresses the operational challenges created by the increasing share of intermittent renewable generation in power systems. In this context, Eiffage Énergie Systèmes and Entech formed a joint venture to respond to a tender covering the design, construction, operation and maintenance of a grid-connected BESS facility.

The cooperation is based on complementary expertise. Eiffage Énergie Systèmes acts as the industrial integrator and infrastructure contractor for complex electrical installations, while Entech contributes specialist know-how in energy storage engineering and intelligent control of battery systems.

Technical solution and division of responsibilities
The project involves a BESS plant with an installed power of 50 MW and an energy capacity of up to 100 MWh. The system is designed for daily charge and discharge cycles, one to two times per day, over an expected operational lifetime of approximately fifteen years.

Eiffage Énergie Systèmes is responsible for overall design, engineering and construction, including civil works, roads and utilities, high- and medium-voltage electrical equipment, AC and DC power systems, automation and supervisory control systems. Entech is in charge of the energy storage architecture, battery sizing and the energy management and control algorithms.

Architecture and grid integration
The facility is organised into six modular and replicable technical islands connected to a dedicated high-voltage substation. Each island includes four 5 MWh battery containers and two medium-voltage station (MVS) containers. Stored energy flows from the batteries through DC/AC power converters and is then stepped up to 33 kV via transformers before being injected into the transmission network operated by RTE.

This modular architecture supports integration with existing grid infrastructure while limiting technical interfaces, in line with the requirements of an Engineering, Procurement and Construction (EPC) delivery model.

Operation, maintenance and use cases
The contract includes a long-term operation and maintenance (O&M) component, delivered by Eiffage Énergie Systèmes in partnership with Envision Energy, the battery supplier. The installation is designed to provide frequency containment reserve (FCR) services, supporting frequency control, voltage regulation and overall grid stability.

www.eiffage.com