Envision Energy and French independent renewable producer Kallista Energy have broken ground on the 193 MW/386 MWh Neuilly-en-Thelle battery energy storage system (BESS) in the Hauts-de-France region, the pair's second joint battery project after the Saleux plant that started construction in 2025.
Second project, same partnership
Construction began in early July 2026, with commercial operations targeted before spring 2028. Envision Energy will supply its BESS solution and manage the full lifecycle, including operation, maintenance and battery recycling after the plant's planned 25-year operating life.
LFP cells from a French gigafactory
The system will use lithium iron phosphate (LFP) battery cells manufactured by Envision AESC at its 10 GWh gigafactory in Hauts-de-France, which has been operational since June 2025. Once commissioned, the plant will provide flexibility services to the French grid — including frequency regulation through RTE's reserve markets — with enough capacity to cover the daily electricity consumption of roughly 30,000 households.
Executive comments
Envision Energy senior vice-president Henry Peng said the project shows the two firms' "continued expansion" in Europe's energy transition, while Kallista Energy CEO Johann Tardy called battery storage "essential for accelerating electrification and expanding renewable energy deployment." The move follows a growing wave of French and European BESS coverage, including Tokyo Gas' Fukushima BESS deal and We Energies' Wisconsin solar-wind-battery groundbreaking.
Reporting based on coverage from SolarQuarter, Envision Energy and Kallista Energy.