I. Framework
What to look for in the framework.
Regarding the framework, consider these six aspects: the five-layer architecture (SunLith Energy: BESS Communication Protocols—The Complete 2026 Guide; Layer 4 EMS [Modbus TCP, OPC UA, MQTT, IEC 60870-5-104]; Layer 5 Grid/Utility SCADA/Cloud [IEC 61850, DNP3, IEEE 2030.5, MQTT, REST]); the use of three or four protocols (SunLith Energy: No single protocol covers all five layers, so most BESS projects combine three or four protocols); IEC 61850 (SunLith Energy: The international standard for substation automation and the leading BESS communication protocol for utility grid connections, especially in Europe and Asia-Pacific; unlike Modbus, it defines a full information model rather than just a transport layer); IEC 60870-5-104 (CNBlogs: A network-extended version of the 103 protocol based on TCP/IP, enabling remote monitoring of power systems—such as communication between dispatch centers and substations); IEC 61850 (CNBlogs: A core smart grid standard for substation automation systems [SAS], supporting high real-time performance, interoperability, and object-oriented data models); and SCADA (ruistelectric: A complete SCADA system for battery energy storage that monitors batteries, PCS, transformers, switchgear, and environmental systems via a unified data architecture; IEC 61850 is the preferred protocol for utility-scale projects, while Modbus TCP dominates commercial and industrial installations). This six-point perspective provides a comprehensive overview of the framework.
II.
National Standards
What to look for in national standards.
Based on the application of national standards, the requirements are interpreted as follows: GB/T 34131 (Section 6.3.2: The battery management system and monitoring system may use Ethernet communication interfaces supporting Modbus, DL/T 634.5104, and all parts of the DL/T 860 communication protocols; dual-network redundancy is recommended); CAN2.0B (Section 6.3.3: The battery management system and energy storage converter may use communication interfaces such as CAN, RS-485, or Ethernet supporting CAN2.0B, Modbus, and all parts of the DL/T 860 protocols, and must feature a hard-wired output contact interface); Section 6.3.4 (Communication interfaces such as CAN, RS-485, or Ethernet supporting CAN2.0B may be used between battery management systems at different management levels); DL/T 1989 (The communication protocol DL/T 1989—2019 for monitoring systems and battery management systems in electrochemical energy storage power stations specifies basic communication principles, interfaces, and message specifications based on DL/T 860.81, DL/T 634.5104, and GB/T 19582.3; it applies to systems with a power rating of no less than 500 kW using lithium-ion, lead-acid, or lead-carbon batteries as the energy storage medium); GB/T 51048 (On December 31, the Ministry of Housing and Urban-Rural Development released GB/T…).
The design standard GB 51048-2025 for electrochemical energy storage power stations comes into effect on April 1, 2026, at which time the previous national standard (GB 51048-2014) is simultaneously repealed. Regarding communication protocols: for the “Technical Specification for Safety Monitoring Information Systems of Electrochemical Energy Storage Power Stations,” the communication protocol between monitoring system platforms should preferably be HTTPS, though HTTP, MQTT, AMQP, and Kafka protocols are also permissible; data formats exchanged between the power station platform and the enterprise platform are to be defined by the enterprise. Key national standards to review include: GB/T 34131, CAN 2.0B, DL/T 1989, and GB/T 51048.
III.
CAN
What to look for regarding CAN.
Based on CAN practices, the perspective is as follows: CAN2.0B—Group Standard (Technical specifications for communication between energy storage battery management systems and power conversion systems in energy storage power stations; the communication system between the BMS and PCS utilizes the CAN2.0B protocol and Modbus serial communication protocol; message bytes follow the principle of transmitting the least significant byte first; reserved bytes are padded with 0x00); CAN Bus—Power Jack Motion (Originating from automotive electronics, this highly reliable communication bus offers strong anti-interference capabilities and is the most common protocol inside battery systems; communication between the slave BMS—which collects cell voltage/temperature—and the master BMS within a battery pack uses the CAN bus protocol); Multi-master—Power Jack Motion (The CAN bus operates completely differently from Modbus’s master-slave mode; it uses a multi-master mode with a priority arbitration mechanism); Ethernet—Xinjiang Administration for Market Regulation (Technical specifications for energy storage system configuration in photovoltaic power stations [DB 65/T 4686—2023]: internal communication within the energy storage system may utilize interfaces such as Ethernet or serial ports; communication protocols may employ bus protocols based on CAN2.0 or Modbus-TCP, implemented in accordance with the provisions of DL/T 634.5101, DL/T 634.5104, or all parts of DL/T 860); CAN/RS485—Xinjiang Administration for Market Regulation (Energy storage power conversion systems should be equipped with CAN/RS485 and Ethernet communication interfaces; specifically, communication between the power conversion system and the monitoring station level should utilize Ethernet interfaces supporting Modbus-TCP, DL/T 860, or PROFIBUS-DP protocols, while communication with the battery management system should utilize CAN); CAN—Mate Solar (CAN Fast Module communication; Battery module BMS).
Solar)—Six Key Aspects of CAN: CAN 2.0B, CAN bus, multi-master, Ethernet, CAN/RS485, and CAN—a comprehensive look at CAN.
IV.
Modbus
What to look for in Modbus.
Based on Modbus implementation practices, here are six perspectives on Modbus: Modbus RTU—China Industrial Association of Power Sources (CIAPS) (Standard T/CIAPS0009—2021 for PCS and BMS communication protocols; RS485 connection using Modbus RTU mode; baud rates of 9600/19200/38400, with 9600 preferred); RS485—CIAPS (standard 2-wire topology, 1 start bit, 8 data bits); GB/T 19582—CIAPS (Technical Specifications for Industrial and Commercial Energy Storage Energy Management Systems T/CIAPS0051—2025; Section 6.4 recommends that communication between the EMS and BMS, PCS, fire protection systems, thermal management equipment, etc., utilize protocols compliant with GB/T 19582 [all parts], DL/T 634.5104, and DL/T 860 [all parts]); MESA-Device—MESA Standards (specifies standardized Modbus communications between ESS components); MODBUS TCP—Mate Solar (communication standard for PCS, BMS, and meters); Modbus—vexenergy (Modbus RTU/TCP is most popular in energy storage; SunSpec is the dedicated standard for photovoltaics; MQTT is for wireless smart home communication). These six perspectives provide a comprehensive overview of Modbus.
V.
Selection
What to consider during selection.
Based on practical selection experience, the criteria are as follows: 104 (IEC 60870-5-104; essential for grid dispatch and mandatory for grid connection); GOOSE (IEC 61850 GOOSE; supports millisecond-level fast control, frequency regulation, and grid-forming capabilities); Dual-network redundancy (GB/T 34131; recommends dual-network redundancy for Ethernet communication between the battery management system and the monitoring system); Dual communication modes (T/HZESA 001—2021; requires communication methods and protocols between the electrochemical energy storage station and the grid dispatch center to comply with DL/T 634.5101, DL/T 634.5104, DL/T 860, and other general power system communication standards, with at least two communication modes supported); DNP3 (MESA Standards/MESA-DER; addresses DNP3 communication between utility control systems and DER sites; evolving into the IEEE 1815.2 standard); IoT model (Modern Electric Power; utilizes IEC 61850 for terminal information modeling and IEC 61968/IEC 61970 for grid modeling, while proposing an IoT model based on IoT rule semantics).
In summary, the selection process focuses on six key aspects: 104, GOOSE, dual-network redundancy, dual communication modes, DNP3, and IoT modeling.
Conclusion
Regarding the protocol standards for energy storage communication modules, the conclusion is…
