Marstek Modbus Companion
Marstek Modbus Companion
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Project description
Marstek Modbus Companion
1. New Content Summary
Marstek Modbus Companion is an ESPHome-based gateway project designed to integrate the Marstek Venus E V3.0 battery storage system with Home Assistant.
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The device communicates with the energy storage system through RS485 using the Modbus RTU protocol and exposes operational data to Home Assistant for monitoring and automation.

The project provides a user-friendly web interface, diagnostic tools, status LED indicators, and supports both Wi-Fi and Ethernet connectivity. The Ethernet version utilizes the W5500 controller, making it suitable for installations where stable wired networking is preferred.

Key Technologies
MCU: ESP32
Ethernet Controller: W5500
Communication Protocol: Modbus RTU (RS485)
Network Interface: Wi-Fi / Ethernet
Software Platform: ESPHome, Home Assistant
Target Device: Marstek Venus E V3.0 Energy Storage System (ESS)
The project demonstrates a practical integration of industrial communication protocols with modern smart-home and energy-management platforms.
2. Similar Existing Content
(1) Modbus TCP
https://maker.wiznet.io/jaden/projects/modbus-tcp-1/
Why it is similar
Uses the Modbus protocol for device communication.
Demonstrates network-based access to industrial data.
Utilizes WIZnet networking solutions.
Focuses on bridging field devices with IP networks.
(2) ESP32 + W5500 Ethernet-Based IoT Projects
Why it is similar
Combines ESP32 and W5500 for Ethernet connectivity.
Collects and transfers device data over a network.
Demonstrates practical IoT deployment using wired Ethernet.
Shares a similar architecture for integrating embedded devices into larger monitoring systems.
(3) Home Assistant Integration Projects on Maker
Why it is similar
Connects embedded hardware to Home Assistant.
Focuses on real-time monitoring and automation.
Uses network-enabled devices to expose sensor and system data.
Demonstrates smart-home and energy-management use cases.
3. Differences and Extension Value
While existing Modbus-related projects on Maker primarily focus on implementing Modbus TCP communication or demonstrating protocol functionality, Marstek Modbus Companion provides a complete real-world application targeting a commercial energy storage system.
Its main differentiators include:
Direct integration with a commercial ESS product (Marstek Venus E V3.0)
Native Home Assistant compatibility
Support for both Wi-Fi and W5500 Ethernet connectivity
User-oriented diagnostics and monitoring features
Energy-management-focused application rather than protocol demonstration
Potential Extensions
Modbus RTU-to-Modbus TCP gateway functionality
Integration with Home Assistant Energy Dashboard
Centralized monitoring of solar inverters, smart meters, and ESS devices
Industrial Energy Management System (EMS) integration
Remote monitoring through Ethernet-based infrastructure
Expansion into broader Industrial IoT and smart energy applications using WIZnet networking solutions
This project serves as a practical example of how WIZnet-powered Ethernet connectivity can be combined with Modbus-based industrial equipment and modern home energy platforms to create reliable monitoring and control solutions.
