At ESS Europe 2025, Chinese battery giant CATL made headlines by unveiling the world’s first 9MWh ultra-large capacity energy storage system solution, the TENER Stack. Designed for mass production, the innovative system represents a major step forward in addressing growing global energy needs, from AI-driven data centres to industrial electrification, while offering unprecedented improvements in capacity, safety, flexibility, and transportability.
Amanda Xu, CTO ESS & President of ESS Europe CATL, emphasised the strategic thinking behind the TENER Stack, stating that the solution is built to meet industry expectations for higher energy density, a reduced footprint, simpler AC-side configuration, and deployment flexibility. The TENER Stack features CATL’s advanced high-energy-density cells and incorporates their proprietary five-year zero degradation technology. Compared to conventional 20-foot container systems, it achieves a 45% improvement in volume utilisation and a 50% increase in projected energy density. Its internal capacity reaches 9MWh, enough to charge approximately 150 electric vehicles or power an average German household for six years.
The system is engineered for versatility and integration, supporting both centralised and string Power Conversion System (PCS) architectures. This dual-path approach ensures compatibility with mainstream AC-side infrastructure and broadens the range of grid applications where the system can be used. TENER Stack’s exceptional space efficiency also translates into economic advantages for developers. For instance, deploying 800 MWh of energy storage using TENER Stack requires about one-third fewer containers than with traditional 6 MWh systems. This significantly reduces the number of PCS units needed, minimises hidden oversizing costs, and improves land-use efficiency by up to 40%, resulting in up to 20% lower overall station construction expenses.
Addressing transportation challenges, particularly with units exceeding the 36-tonne legal limit in many countries, CATL introduced a “two-in-one” design. Each half-height unit remains under the 36-tonne threshold, ensuring compliance with transport regulations in 99% of global markets. This split format also supports standard shipping infrastructure, reducing waiting times and specialised transport costs by as much as 35%. Additionally, the lower centre of gravity and modular design facilitate navigation through height-restricted or remote areas, such as rural roads and bridges, highlighting the Stack’s practical structural advantages.
Safety has also been a core focus of the TENER Stack. Built with CATL’s thermally stable LFP battery chemistry, the system features upgraded gas sensors that are 40% more sensitive, triggering suppression mechanisms 35% faster. A new triple-layer insulation design boosts fire resistance to two hours, while the structure complies with IEEE693 seismic standards, making it resilient enough to withstand magnitude 9 earthquakes and Category 5 hurricanes.
The TENER Stack also incorporates an overhead Thermal Management System (TMS) that reduces thermal radiation, cuts land and maintenance costs, and maintains operational noise below 65 decibels at one metre—making it suitable for deployment in urban settings.
By the end of November 2024, CATL’s energy storage solutions had been deployed in over 1,700 projects across diverse environments worldwide. The TENER Stack builds on the success of its predecessors the containerised TENER and the flexible TENER FLEX systems bringing new levels of performance, capacity, and transportability to the market.
Hank Zhao, CTO of ESS Europe CATL, summed up the innovation by saying, “TENER Stack, giant, flexible, reliable and quiet. We are not only delivering an energy storage product, but a solution for energy accessibility that can be applied globally.” He added that 9MWh is not the ceiling, hinting that future breakthroughs in energy density will continue to extract more value from increasingly compact footprints.
With the launch of TENER Stack, CATL reaffirms its role as a global leader in energy storage innovation, delivering scalable and sustainable solutions that support the world’s transition to cleaner, more efficient energy systems.
