Symm 261

125 kW C&I BESS

The Brunstock Symm 261 battery energy storage system is a 125 kW (261 kWh) BESS purpose-built for commercial and industrial operators who demand reliability, resilience and control. Whether they are managing heavy loads, integrating renewables or protecting against grid instability, this system gives them the freedom to take charge of their energy future.

Empowering business users with
energy independence

In the midst of the global energy transition, loads and generation fluctuate more than ever before. Renewables surge and decline. Demand peaks and falls unpredictably. Stability is no longer a given; it must be engineered.

Across every level of the modern energy ecosystem—from grid-scale storage to behind-the-meter systems—balance is essential.

Why our liquid cooling

is class-leading

Seamless microgrid integration

• Connect effortlessly with solar, wind, generators and EV charging
• Operate grid connected or completely islanded
• Fast-acting controls stabilise frequency, voltage and load
• Unlock services like peak shaving, load balancing and resilience support

Scalable, modular design

• Start with a single 125 kW unit and expand to multiple unit systems
• Parallel ready architecture grows with your facility’s demand
• Ideal for seasonal or expanding operations
• Invest in phases to match your business growth

Flexible configurations

• Optional DC-only variant for third party PCS integration
• Perfect for unique grid codes or local supplier requirements
• Supports hybrid microgrids with multi-brand electronics
• Retains Brunstock’s proven enclosure, safety and design standards

Optimised for heavy power users

• Cut demand charges and avoid costly penalties
• Shift large loads to off peak tariffs
• Smooth operation of motors, chillers, pumps and compressors
• Store renewable energy and release it when it matters most

Energy arbitrage for maximum savings

• Charge during off peak or solar excess periods
• Discharge during peak demand windows
• Intelligent scheduling tailored to your consumption patterns

Engineered for reliability

• Industrial-grade liquid cooling
• Maintains uniform cell temperature in extreme heat, cold or humidity
• Superior heat dissipation extends battery life
• Enables high power cycling without derating
• Enhanced safety through stable thermal operation

World-class architecture & design

• Clean, industrial aesthetic for visible commercial sites
• High grade materials resist corrosion and weather extremes
• Ergonomic layout for fast servicing and minimal downtime
• Certified to IEC standards for global compliance

Future-proof engineering

• Tier one power electronics with Brunstock AC/DC expertise
• Advanced BMS with multi-layer safety and lifecycle protection
• Scalable design supports long term site growth

• Grid-following mode for standard on-grid operation with utility synchronisation and a smart operation interface
• Grid-forming mode for islanded and off-grid applications with independent voltage/frequency control
• Seamless transition between grid-connected and islanded modes (<20ms transfer time)
• Black start capability for dead bus energisation without external supply
• Voltage regulation accuracy ±2% and frequency regulation ±0.5% of nominal
• Configurable droop settings and load sharing for parallel PCS operation

• Refined thermal management, with pack temperature difference ≤3°C
• Fault ride-through compliant with regional grid code requirements
• Configurable fault current contribution magnitude and duration in grid-forming mode
• Motor starting and transformer inrush current handling capability
• Protection coordination support for site-specific requirements
• Grid synchronisation protocols for safe reconnection after islanding
• IEC 62933 BESS compliance with grid-forming inverter standards