Fluence expands Smartstack platform with high-density 10 MWh BESS option

Fluence Energy has introduced a 10 MWh configuration for its Smartstack utility-scale battery energy storage system platform, expanding on its existing 7.5 MWh option.  

The new high-density system gives developers a higher-capacity alternative that utilizes the same electrical architecture and deployment model as the existing Smartstack line. By upgrading the battery pod design, Fluence achieves a core site-level energy density of approximately 680 MWh per acre, enabling utilities to maximize capacity on constrained plots of land and reducing balance-of-plant costs by up to 40% compared to standard DC blocks.  

The split-architecture design separates the hardware into distinct skids and battery pods to optimize shipping and installation. While both variants utilize standard 3XX Ah capacity cells, a maximum DC voltage of up to 1,500 V, and an AC voltage rating of 690 V, their physical specifications differ. The 10 MWh variant features battery pods weighing approximately 20,000 kg and measuring 1,764 x 2,656 x 2,524 mm, alongside a 10,000 kg smart skid.  

In comparison, the 7.5 MWh variant features 15,000 kg pods measuring 1,764 x 2,656 x 3,330 mm and a 10,000 kg smart skid. Performance metrics also shift, with the 10 MWh tier offering a maximum AC output current of 2,508 A and discharge durations of 4, 6, or 8 hours, compared to the 7.5 MWh tier’s 3,762 A output and 2- to 8-hour durations.  

Standardizing the balance-of-plant layout across both capacity options helps developers bypass major design adjustments as battery chemistries evolve. To limit geopolitical and supply chain vulnerabilities, Fluence develops its operational control software entirely in-house.  

The company relies on a regionalized, diversified global supplier base to blend domestic and foreign manufacturing sources, creating an optimal mix that protects against changing trade and policy environments.  

The BESS operates on Fluence OS7 software, integrating Modbus, DNP3, and OPC UA communication protocols. For asset management and financial dispatching, the hardware hooks into Fluence Nispera for analytics and the Fluence Mosaic bidding optimization platform. The automated controls facilitate continuous, real-time temperature tracking and automated state-of-charge recalibration. 

The system features liquid-cooled thermal management housed within an IP55-rated battery enclosure, providing a C3 to C5 chemical and corrosion resistance rating under ISO 12944-6 standards.  

The product operates at ambient temperatures from -30°C to +55°C, with automated derating kicking in past 50°C.  

For fire safety, the architecture introduces isolated containment zones with specific spacing to prevent pod-to-pod thermal propagation, meeting UL9540, UL9540A, and NFPA standards. Fluence supports the hardware with a guaranteed 25-year system lifetime and offers performance structures that ensure up to 99% fleet availability.

From pv magazine USA