Battery Storage Knowledge Bank

Northern Power Systems - Eos

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Eos has developed a low-cost zinc-based battery with a projected lifetime of around 30 years (10,000 cycles).  

Northern Power Systems has in turn developed an integrated energy storage system (ESS) combining the Eos Aurora DC battery system with power converter technology and controls from Northern Power. The resulting turnkey ESS solution is designed to provide 4 hours of usable energy from modular 250 kW battery units, scalable up to multi-MW level.

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NPS Converter

The combined ESS utilises Northern Power’s FlexPhase inverter technology, with power output ranging from 500 kW to 2,000 kW. The key features of this inverter technology are:

  • Flexibility. Modular plug & play technology that can be integrated into a single enclosure (both IP65 and IP54 rated options available for outdoor and indoor use, respectively).
  • High spec. High efficiency (>98%) and power density, and fast response times (<1 ms).
  • Functionality. Designed for all main commercial storage applications (see below), including the ability to operate in, and transition seamlessly between, both grid-conected and islanded operation modes.
  • Compatibility. Supports all standard communication protocols and interfaces (PROFINET, Modbus TCP, RS485, Ethernet & CAN) and can be used with most battery chemistries due to wide DC voltage range (up to 1,150 VDC). 
  • Proven technology. With over 150 MW of converters deployed globally, Northern Power Systems converter technology is proven to deliver real world performance.   

Eos Aurora Battery

Eos’ unique aqueous zinc hybrid cathode technology (Zynth) provides a low-cost battery storage solution for the combined ESS, with the following characteristics:

  • Low cost/kWh. Utilises inexpensive, widely available materials, combined with highly standardised manufacturing processes to deliver a cost-competitive storage solution.
  • Long life. Robust design with projected lifetime of 5,000 cycles/15-year calendar life.
  • Energy density. Can house a capacity of 1 MWh within a single 40-foot container.
  • Efficiency. Round trip efficiency of 75% for 100% DoD applications.
  • Safety. Made from benign, non-toxic materials.


The NPS-Eos ESS can be utilised for all the main commercial energy storage applications, such as:

  • Peak shaving – buy cheap, use peak! Charge the battery at off-peak rates, discharge at times of peak demand to reduce expensive demand charges.
  • Load shifting. Shift energy consumption from one point in time to another.
  • Micro-grid / emergency backup. Build a localised grid that can island a site from the main grid as and when required.
  • Demand response / grid balancing services. Discharge or charge in response to signals from a demand response administrator. Supply Frequency Regulation services and Capacity Market support to the grid when required.
  • Transmission and distribution support. Supply increased power to a site to defer the need to upgrade the grid connection.

Technical specifications

Area requirements

500 kW/2000 kWh: 128 m2  

1000 kW/4000 kWh: 188 m2 

Operating ambient temperature -25-50°C
System sizes Scalable from 250 kW - 2 MW
Continuous power duration 4 hours
System efficiency at 100% DoD 74%
Control interface MODBUS/TCP, DNP3