Growatt MOD 5000TL3-X ESPHome Modbus Integration

A complete, tested ESPHome configuration for monitoring Growatt MOD 5000TL3-X solar inverters via RS485 Modbus RTU protocol, integrated with Home Assistant and/or MQTT for real-time solar energy monitoring. The setup additionally allows the user to limit the inverter power output (wattage), or turn the inverter on and off altogether.

1. Architecture Overview

System Architecture

This project creates a complete solar monitoring and control solution using a modern, local-first approach:

Solar Panels → Growatt MOD 5000TL3-X Inverter → RS485/Modbus RTU → LilyGO T-CAN485 ESP32 → WiFi → Home Assistant / MQTT

Component Roles

Home Assistant

Central monitoring and automation platform
Real-time dashboards and energy analytics
Historical data storage and visualization
Automation triggers based on solar production

ESPHome

ESP32 Firmware platform providing seamless Home Assistant integration
Automatic device discovery and configuration
Over-the-air (OTA) updates
Native Home Assistant API integration

LilyGO T-CAN485 ESP32 Board

ESP32 microcontroller with built-in RS485 transceiver, no soldering or wiring required.
Eliminates need for external RS485 converter circuits
WiFi connectivity for Home Assistant communication
GPIO pins pre-configured for RS485 communication

Modbus RTU Protocol

Industrial-standard communication protocol
Reliable data transmission over RS485
Supports multiple data types (16-bit, 32-bit integers)
Error detection and correction

Growatt MOD 5000TL3-X Inverter

Solar inverter with built-in SYS COM port
Modbus RTU slave device (default address: 1)
Provides real-time solar production data
System status and diagnostic information

Data Flow

Solar Production: Inverter converts DC from panels to AC for grid
Data Collection: Inverter continuously updates internal registers
Modbus Communication: ESP32 polls inverter every 30 seconds via RS485
Data Processing: ESPHome processes raw Modbus data and applies scaling
Home Assistant Integration: Processed data sent via WiFi to Home Assistant
Visualization: Real-time dashboards, historical charts, and automation triggers

Benefits

Local Control: No cloud dependency, works offline
Real-time Monitoring: 30-second update intervals, or less
Professional Integration: Native Home Assistant device discovery
Expandable: Easy to add multiple inverters or additional sensors
Reliable: Industrial Modbus protocol ensures data integrity

2. Hardware Components and Wiring

Why LilyGO T-CAN485 Makes This Simple

The LilyGO T-CAN485 board is specifically designed for industrial communication applications, making this project straightforward:

Built-in RS485 Transceiver

No external RS485 converter needed
No complex wiring diagrams
No additional components to purchase
Professional-grade signal conditioning

Integrated Design

ESP32 microcontroller with WiFi
RS485 transceiver on-board
Power management included
Compact form factor

Pre-configured LiliGo GPIO Mapping

GPIO21: RS485 RX (connects to RS485-B)
GPIO22: RS485 TX (connects to RS485-A)
GPIO16: 5V rail enable for RS485 chip
GPIO17: Auto-direction control
GPIO19: RS485 chip enable

Required Components

Component	Description	Where I got it
LilyGO T-CAN485	ESP32 Development Board with RS485	TinyTronics SKU: 005278 - €16,50
External antenna	Antenna for ESP32 development board	TinyTronics SKU: 001098 - €2,00
Growatt 16-pin COM Connector	SYS COM port connector	Stralend Groen
2-Wire Cable	RS485 communication cable	Any electronics supplier.
USB-C Power Supply	For LiliGo board	TinyTronics SKU: 002192 - €9,00
IP65 Enclosure	Weatherproof housing	TinyTronics SKU: 001800 - €8,00

Cable Assembly Instructions

SYS COM Port Pinout

Important: Always refer to the official Growatt MOD Inverter Documentation for complete SYS COM port specifications.

Pin Connections

Based on the Growatt MOD series documentation, the 16-pin SYS COM connector uses the following pins for RS485 communication:

Growatt SYS COM Pin	Function	LilyGO T-CAN485 Pin
Pin 3	RS485-A	GPIO22 (TX)
Pin 4	RS485-B	GPIO21 (RX)

Wiring Steps

Prepare the data wire
- Strip 5mm of insulation from 2-wire cable on both ends
Connect wires to Growatt SYS COM Port and LiliGo terminals
- Pin 3 (RS485-A) → GPIO22 RS485 terminal on LiliGo
- Pin 4 (RS485-B) → GPIO21 RS485 terminal on LiliGo

3. ESP32 Configuration with ESPHome

ESPHome Web Interface Setup

Instead of using command-line tools, we'll use the ESPHome web interface for a user-friendly configuration experience.

Open ESPHome dashboard
Click + NEW DEVICE, and follow the instructions on the screen.
Enter device name: growatt-tcan485
Select ESP32 as device type
Choose ESP32 Dev Module board

Step 3: Configuration File

Use the provided growatt-liligo-tcan485.yaml configuration file as an example, and copy sections over to the config esphome created. (Do not use API key, OTA password, and fallback WiFi key from the yaml in this repository. Esphome should have created those for you on adding a new device)

Step 4: Upload Firmware via Web Interface

Prepare secrets.yaml

wifi_ssid: "Your_WiFi_Network"
wifi_password: "Your_WiFi_Password"

Compile Firmware
- Click INSTALL in ESPHome dashboard
- Select Manual download
- Wait for compilation to complete
Initial Upload via USB
- Connect ESP32 to computer via USB-C
- Click Plug into this computer
- Select the compiled firmware file
- Upload to device
Subsequent Updates (OTA)
- After initial setup, updates can be done wirelessly
- ESPHome will update over WiFi

Step 5: Verify Connection

Check ESPHome Logs
- Click LOGS in ESPHome dashboard
- Verify WiFi connection
- Check Modbus communication

Troubleshooting Common Issues

No Modbus Communication

Verify RS485 wiring (A and B may be swapped)
Check inverter is powered and operational

WiFi Connection Issues

Check secrets.yaml file
Verify WiFi credentials
Use fallback hotspot if needed

Compilation Errors

Ensure ESPHome is up to date
Check YAML syntax
Verify all required libraries are available

4. Modbus Registers Explanation

Understanding Modbus Register Types

The Growatt inverter uses two types of Modbus registers:

Holding Registers (Function Code 3)

Read/write registers for configuration
Used for inverter settings and control
Examples: On/Off control, power limits

Input Registers (Function Code 4)

Read-only registers for measurements
Real-time sensor data and status
Examples: Power output, energy totals, voltages

32-bit Integer Handling

Many important values (power, energy) are stored as 32-bit integers across two consecutive 16-bit registers:

Why register_count: 2 is Required

- platform: modbus_controller
  name: "Growatt AC Output Power"
  address: 35           # Start address (Pac H)
  register_count: 2     # Read 2 registers (35 + 36)
  value_type: U_DWORD   # Unsigned 32-bit integer
  filters:
    - multiply: 0.1     # Convert to watts

Register Layout for 32-bit Values

High Register: Contains upper 16 bits
Low Register: Contains lower 16 bits
Combined: Forms complete 32-bit value

Key Register Mappings

Based on the growatt-liligo-tcan485.yaml configuration and Growatt Modbus Documentation:

Power Measurements

YAML Address	Modbus Register	Description	Data Type	Scaling	Unit
35-36	Pac H/L	AC Output Power	U_DWORD	×0.1	W
5-6	Ppv1 H/L	PV1 Input Power	U_DWORD	×0.1	W
9-10	Ppv2 H/L	PV2 Input Power	U_DWORD	×0.1	W

Energy Totals

YAML Address	Modbus Register	Description	Data Type	Scaling	Unit
53-54	EAC today H/L	Daily Energy Production	U_DWORD	×0.1	kWh
55-56	EAC total H/L	Total Energy Production	U_DWORD	×0.1	kWh

Voltage and Current

YAML Address	Modbus Register	Description	Data Type	Scaling	Unit
3	Vpv1	PV1 Voltage	U_WORD	×0.1	V
7	Vpv2	PV2 Voltage	U_WORD	×0.1	V
4	PV1Curr	PV1 Current	U_WORD	×0.1	A
8	PV2Curr	PV2 Current	U_WORD	×0.1	A
38	Vac1	Grid Voltage	U_WORD	×0.1	V
37	Fac	Grid Frequency	U_WORD	×0.01	Hz

Status and Diagnostics

YAML Address	Modbus Register	Description	Data Type	Values
0	Inverter Status	Operating State	U_WORD	0=Waiting, 1=Normal, 3=Fault
93	Temp1	Inverter Temperature	U_WORD	×0.1 °C
105	Fault Code	Error Code	U_WORD	See fault code table

Control Registers (Holding)

YAML Address	Modbus Register	Description	Data Type	Range
0	OnOff	Remote On/Off	U_WORD	0=Off, 1=On
3	Active P Rate	Power Limit	U_WORD	0-100%

Data Scaling Examples

Power Reading Example

# Raw Modbus value: 25000 (from registers 35-36)
# Scaled value: 25000 × 0.1 = 2500.0 W
filters:
  - multiply: 0.1

Energy Reading Example

# Raw Modbus value: 1234 (from registers 53-54)
# Scaled value: 1234 × 0.1 = 123.4 kWh
filters:
  - multiply: 0.1

Frequency Reading Example

# Raw Modbus value: 5000 (from register 37)
# Scaled value: 5000 × 0.01 = 50.00 Hz
filters:
  - multiply: 0.01

Register Documentation Cross-Reference

This configuration has been verified against:

growatt-modbus-docs.pdf: Complete Modbus register specification
growatt-mod-inverter-docs.pdf: MOD series hardware documentation
Actual MOD 5000TL3-X inverter: Field-tested and verified

Home Assistant Integration

Once configured, the following entities will automatically appear in Home Assistant:

🚨 Safety and Installation Notes

⚠️ WARNING: High Voltage Present

Always disconnect AC and DC power before wiring
Use insulated tools and follow electrical safety procedures

Installation Requirements

Must be installed by qualified electrical personnel
Comply with local electrical codes and regulations
Obtain necessary permits and utility approvals

System Compatibility

✅ Tested with Growatt MOD 5000TL3-X

📚 Documentation References

Status: ✅ Fully tested and operational with Growatt MOD 5000TL3-X

Name		Name	Last commit message	Last commit date
Latest commit History 3 Commits
doc_img		doc_img
README.md		README.md
growatt-liligo-tcan485.yaml		growatt-liligo-tcan485.yaml
growatt-mod-inverter-docs.pdf		growatt-mod-inverter-docs.pdf
growatt-modbus-docs.pdf		growatt-modbus-docs.pdf

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