Sungrow PowerStack 255CS

Commercial battery energy storage system

PowerStack 255CS is Sungrow's liquid-cooled C&I cabinet: 257 kWh of LFP and a 125 kW DC/AC converter at 400 V. The datasheet names Ethernet and Modbus TCP; the optional EMS300CP inside the cabinet door is the part that joins the customer network. Edge reads it over Modbus TCP from the project point list, or measures the cabinet's AC feeder with an EpiSensor ZEM-65.

Sungrow PowerStack 255CS (ST255CS-2H)
  • Modbus TCP

Commercial battery energy storage system

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Compatibility

Compatible with EpiSensor Edge over Modbus TCP from the EMS300CP, or through a ZEM-65 on its AC feeder

Sungrow's datasheet names Ethernet and Modbus TCP for the ST255CS-2H, and the user manual has the ESS with an EMS300CP join the customer network through the EMS Ethernet ports. Edge is a Modbus TCP client and reads that interface from the point list Sungrow supplies for the project. Without that list, an EpiSensor ZEM-65 with CTs on the 400 V AC feeder measures the cabinet's charge and discharge at its AC boundary.

ST255CS-2H (IEC) with datasheet Version 2 and user manual ST255CS-2H-UEN-Ver11-202512. Site check: confirm whether the cabinet carries an EMS300CP, obtain the EMS point list for its firmware, and record whether the auxiliary supply is internal or external. Read-only monitoring; no scheduling, power or on/off writes.

Connect it with

Route into Edge

When the cabinet carries an EMS300CP and Sungrow supplies its point list for the installed firmware

  • Wired
  • Edge
  • Platforms
Commercial battery energy storage system
Interface
Gateway
Edge
Output
PowerStack 255CSPowerStack 255CS with EMS300CP
Sungrow EMS300CPOptional EMS controller inside the cabinet door; collects ESS and meter data
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeModbus client + register map
Customer platformMQTT · API · files
Factory wiring to the ESS
ETH1 or ETH2, Modbus TCP, read only
Runs locally
Optional onward data
The ESS with the EMS joins the customer network, and other cabinets connect to it through NET7 and NET8. Configure Edge from the EMS point list: start with identity, state, SOC, AC power and alarms, and compare them with the EMS300CP local web and a connection-point meter. Read only. The customer-platform output is optional; Edge remains the local system of record.

For charge and discharge power and energy at the 400 V AC connection, with or without a point list

  • Wired
  • Edge
  • Platforms
Commercial battery energy storage system
Interface
Gateway
Edge
Output
PowerStack 255CSST255CS-2H 400 V AC output
EpiSensor ZEM-65Measures the cabinet's AC feeder with its own CTs and reports over the EpiSensor wireless network
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeProtocol client + point model
Customer platformMQTT · API · files
CTs and voltage reference on the 400 V feeder
EpiSensor wireless
Runs locally
Optional onward data
A qualified electrician fits CTs sized for the feeder current on the three phases of the cabinet feeder and connects the ZEM-65's voltage reference. The ZEM-65 reports over the EpiSensor wireless network, so nothing changes in the cabinet, the EMS or iSolarCloud. Keep dispatch with the existing EMS. The customer-platform output is optional; Edge remains the local system of record.

Models

Download
ModelsInterfaceRoute into Edge
ST255CS-2H (PowerStack 255CS, IEC)257 kWh, 125 kW, 400 V 3P4L; Ethernet and Modbus TCP; optional EMS300CPRead the EMS300CP over Modbus TCP with the project point list, or meter the AC feeder with a ZEM-65.
ST255CS-2H-USNorth American variant: 125 kVA at 45 °C, 480 V output, Modbus TCP, with its own datasheetUse its own documents; do not transfer IEC ratings or wiring.
PowerTitan 2.0 and other Sungrow utility containersUtility-scale containers with different PCS and EMSUse their own guides.

Specifications

The cabinet combines 257 kWh of LFP cells (3.2 V, 314 Ah, 256S1P) with a 125 kW DC/AC power converter on a 400 V three-phase four-wire connection, cooled by liquid. It runs on-grid, off-grid and with automatic switching.12

Battery
LFP 3.2 V / 314 Ah, 256S1P, 257 kWh nominal, 691.2 to 934.4 V, 0 to 100 % depth of charge and discharge2
AC, on-grid
125 kW nominal, 400 V 3P4L, 340 to 440 V, 50/60 Hz; power factor 1.0 leading to 1.0 lagging2
AC, off-grid
400 V, 50/60 Hz, 100 % unbalanced load capacity2
Communication
Ethernet, Modbus TCP2
Default IP addresses
LC-ETH1 192.168.1.100, LC-ETH2 192.168.13.100; EMS ETH1 192.168.13.200, ETH2 192.168.1.200, ETH5 13.13.13.133
Enclosure and environment
IP55; anti-corrosion C4 (default) or C5 (optional); -30 to 50 °C, derating above 45 °C; up to 3,000 m; 65 dB or less at 1 m2
Size and supply
1150 x 2450 x 1610 mm, 3200 kg or less; internal auxiliary power supply (default) or external (optional)2
Parallel operation
Up to 25 cabinets in parallel on-grid23
Standards
IEC 62619, IEC 63056, IEC 62040, IEC 62477, IEC 61000, IEC 62933, UN 38.32

Interface

Documented measurements and integration boundaries for PowerStack 255CS.

  • Sungrow publishes no public point list for the EMS300CP or the cabinet. Identity, operating state, SOC, SOH, AC power, energy and alarms come from the EMS point list for the installed firmware; keep each value's source, sign, unit and timestamp.
  • Through a ZEM-65 on the feeder: active power, energy in each direction, and current and voltage per phase at the cabinet's 400 V AC terminals. Record whether the auxiliary supply is internal (the default) or external, because that changes what the feeder carries.
  • The EMS300CP needs a gateway meter, an overload monitoring meter and an electricity meter for some functions. Leave those meters in their roles; Edge does not take their bus.
  • Third Party Scheduling (Fixed Value) on the EMS300CP web hands control to a northbound controller. Edge does not use it and sends no scheduling, power or on/off command; control needs the site owner's and Sungrow's agreement.

Assessment

ST255CS-2H (IEC), datasheet Version 2 and user manual Ver11-202512. The EMS point list is project-supplied; scheduling and control are outside this scope.

InteroperabilityLimited
Ethernet and Modbus TCP are named and the EMS network ports are documented, but the register map is not public.23
AccuracyNot yet assessed
The readable point set, units, signs and update rates are not in the public documents; they come from the EMS point list.23
SecurityNot yet assessed
The manual documents ports and default addresses but not authentication or read-only access for a Modbus TCP client.3
ReliabilityLimited
Operating limits and three-level overcurrent and fire protection are published; client timeouts, stale-data behaviour and concurrent-client limits are not.2
RuggednessSupported with conditions
IP55, C4 or C5 corrosion protection, -30 to 50 °C with derating above 45 °C and 3,000 m are published.2
ScalabilitySupported with conditions
Up to 25 cabinets run in parallel on-grid, networked to the cabinet that carries the EMS, so one EMS endpoint serves the group.23
LifecycleSupported with conditions
A current product page, a Version 2 datasheet and a December 2025 user manual cover the model. Record EMS firmware per site.123

Setup

  1. Identify the cabinets

    Record the model and serial from each nameplate, the number of cabinets, which one carries the EMS300CP (the product label says), and the EMS and local controller firmware. The manual's technical data is for reference; the nameplate governs.

  2. Choose the route

    With an EMS300CP and its point list, read it over Modbus TCP. Without them, or for an independent check, fit a ZEM-65 on the cabinet's AC feeder. 125 kW at 400 V is about 180 A per phase at unity power factor; size the CTs for the feeder.

  3. Connect to the EMS network

    The EMS300CP's ETH1 and ETH2 exchange data with a background master through a router or switch. Give it a site address in place of the defaults, put the Gateway on the same protected network and allow only the Gateway to reach the Modbus TCP port.

  4. Start with a small read set

    From the EMS point list, read identity, operating state, SOC and AC power first. Compare them with the EMS300CP local web and with a connection-point meter during a known charge and a known discharge, then add energy and alarms.

  5. Leave scheduling alone

    Do not change Scheduling Mode on the EMS300CP web; Third Party Scheduling (Fixed Value) is for a northbound controller. Record failed reads as unavailable, not zero.

Common questions

Is the Modbus point list public?
No public list was found for the EMS300CP or the cabinet. Ask Sungrow or the commissioning provider for the point list that matches the installed EMS firmware.23
Can an EpiSensor ZEM-65 measure the cabinet?
Yes. The cabinet connects at 400 V three-phase four-wire, within the ZEM-65's supply range, so CTs on the feeder give power and energy in both directions at the AC boundary. That includes conversion losses, and the auxiliary load when the internal supply is used.2
What does Third Party Scheduling do?
It is the EMS300CP mode that lets a northbound controller schedule the cabinet. Monitoring does not need it, and this guide leaves the commissioned mode unchanged.3

Sources

  1. PowerStack 255CS, 125 kW / 257 kWh ST255CS-2H product page (opens in a new tab) Sungrow
  2. ST255CS-2H PowerStack liquid cooled C&I energy storage system datasheet, Version 2 (opens in a new tab) (PDF) Sungrow
  3. Energy Storage System PowerStack-ST255CS-2H User Manual, ST255CS-2H-UEN-Ver11-202512 (opens in a new tab) (PDF) Sungrow
  4. ST255CS-2H-US liquid cooled C&I energy storage system datasheet, Version 1, 2025-04-16 (opens in a new tab) (PDF) Sungrow

Further reading

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