SolaX HS51O HV Battery Module – 5.1kWh Stackable Battery (with Optimiser)
Scalable high-voltage battery storage with the SolaX HS51O battery module. Part of the SolaX TSYS-HS51 platform, the HS51O is a modular lithium iron phosphate (LFP) battery designed for residential and commercial energy storage systems using compatible SolaX inverters.
Each HS51O module provides 5.1kWh of nominal capacity and is installed as part of a stackable high-voltage battery system, allowing capacity to be sized accurately at installation and expanded over time as energy demand increases.
The HS51O is the latest generation of the HS51 battery platform and includes an integrated module-level optimiser, designed to improve long-term usable energy and balancing performance when used within a fully optimised battery stack.
Important: The HS51O battery module cannot operate on its own. A compatible SolaX BMU is required to form a complete battery system.
Series Box requirement: A SolaX HS51O Series Box is only required when installing 9 or more battery modules (i.e. more than 8), where a second battery tower is used.
Included in Kit
- 1x SolaX HS51O High-Voltage Battery Module (5.1kWh)
Building a system? A compatible SolaX HS51 / HS51O BMU is required to operate the battery stack. Additional HS51 or HS51O battery modules can be added to increase total capacity (subject to system limits).
Battery Configuration & System Requirements (Important)
- Minimum system requirement:
- 1x SolaX HS51 / HS51O BMU
- At least 2x HS51 or HS51O battery modules (minimum stack height)
- Single battery tower:
- Up to 8 battery modules may be installed in a single tower (manufacturer guidance)
- Two-tower configuration:
- When installing 9 or more battery modules, a Series Box is required
- A configuration of 7 + 6 battery modules is commonly recommended
- Maximum capacity and system limits depend on:
- Inverter model
- Single-phase vs three-phase configuration
- Whether battery ports are paralleled
If you are unsure which configuration is suitable for your inverter or site, please contact us before ordering.
Key Features of the SolaX HS51O Battery Module
- 5.1kWh nominal capacity per battery module
- High-voltage lithium iron phosphate (LFP) chemistry
- Integrated optimiser for improved long-term usable energy
- Up to 10% increase in effective usable energy over the battery life cycle (lab conditions)
- 3-hour rapid equalisation for improved module balancing
- Stackable modular architecture
- Plug-and-play expansion with no system downtime
- Compatible with existing HS51 batteries
- IP66 rated – suitable for indoor or outdoor installation
- Aerosol fire suppression module for enhanced safety
Optimiser Function & Compatibility
The integrated optimiser in the HS51O is designed to improve balancing behaviour and maintain usable energy as the battery system ages.
- The optimiser function is active when all battery modules in the stack are HS51O models
- HS51O batteries can be mixed with standard HS51 batteries
- When mixed, optimiser functionality is disabled across the entire stack and the system operates as a standard HS51 battery system
This allows for backwards-compatible system upgrades without requiring full replacement of existing batteries.
Core Electrical Specifications
- Module capacity: 5.1kWh
- Battery type: Lithium Iron Phosphate (LFP)
- Depth of Discharge: 90%
- Cycle life: >6000 cycles (90% DoD)
- Communication: CAN / RS485
Physical Specifications
- Dimensions (W x H x D): 600 ร 168 ร 376 mm
- Weight: 47.1 kg
- Installation type: Stackable, floor mounted
- Ingress protection: IP66
Environmental & Safety
- Operating temperature: -20ยฐC to +53ยฐC (without heating)
- Battery heating support (system dependent)
- Aerosol fire suppression for internal protection
Frequently Asked Questions
What is the SolaX HS51O battery?
Do I need a BMU?
When do I need a Series Box?
Can HS51O batteries be mixed with standard HS51 batteries?
Product Code: TB-HS51O
Learn More: https://www.solaxpower.com/products/tsys-hs51.html
Downloads
Datasheet โ SolaX TSYS-HS51 / HS51O
Installation Guide
User Manual
Order the SolaX HS51O battery module today from The Eco Supermarket for fast UK delivery, expert technical support and full manufacturer warranty.







