EPC delivery of a ground-mounted photovoltaic power plant in eastern France

In July 2024, Eiffage Énergie Systèmes was selected to deliver the EPC scope—excluding PV modules—for a 23.4 MWp ground-mounted solar power plant in Réguisheim, eastern France. Once operational, the facility is expected to produce sufficient electricity to supply approximately 7,500 households annually, excluding heating and domestic hot water.

Project context and roles
The photovoltaic project is being developed and financed by Tryba Energy, which secured a long-term land lease (minimum 30 years), conducted preliminary studies, and managed regulatory processes, including environmental assessments and permitting. Following approval by the French Energy Regulatory Commission, the project was awarded under a tender procedure and structured as an EPC contract, with Tryba Energy supplying the PV modules and Eiffage Énergie Systèmes responsible for turnkey delivery of the balance-of-plant.

The site is a former gravel pit that had been inactive for more than a decade. Its redevelopment required specific technical solutions due to geotechnical constraints and flood risk associated with extreme Rhine water levels.

Technical design and electrical architecture
The installation is divided into two adjacent plants to comply with grid connection constraints: a 20.2 MWp southern section and a 3.2 MWp northern section, totaling 23.4 MWp. Two combined delivery and transformer substations were installed, each connected to a separate Enedis substation, alongside four additional transformer substations serving the southern section.

PV modules are connected in series in strings of 27 units feeding inverters that convert 1,500 V DC into 800 V AC. The plant comprises 59 inverters (51 in the southern section and 8 in the northern section), connected via three-phase AC to transformer substations and then to a central 800 V AC busbar. At transformer outputs, electricity is stepped up to 20 kV and injected into the medium-voltage grid via dedicated MV switchgear.

Civil works and site-specific constraints
Due to flood risk, all electrical equipment and structures were designed for elevated installation. Approximately 10,000 driven piles, embedded 2 to 2.5 metres into the former gravel pit, support the metal structures. Some structural columns reach up to 6 metres in height, ensuring equipment remains above potential flood levels while maintaining precise module alignment.

Eiffage Énergie Systèmes coordinated civil engineering works, access roads, fencing, cable trenching, and the installation of metal structures through specialized partners.

Environmental measures and compliance
The project required a protected species derogation, accompanied by compensatory ecological measures. Of the 40-hectare site, only 23 hectares are occupied by the power plant, with the remaining 17 hectares dedicated to biodiversity enhancement. Measures include the creation of hibernacula for reptiles and amphibians, nesting boxes, restoration of grassland habitats, and dedicated gravel platforms for the stone curlew. Invasive species management was also implemented as part of environmental monitoring.

Expected impact
The Réguisheim photovoltaic project combines complex electrical engineering, flood-resilient design, and environmental mitigation. It contributes to regional renewable energy capacity while reinforcing Eiffage Énergie Systèmes’ position as a key EPC contractor supporting the energy transition in France’s Grand Est region.

www.eiffage.com