This sketch runs on an ESP8266 and reads data from Growatt Solar Inverter over RS485 Modbus and publishes the data over MQTT. This code can be modified for any Gorwatt inverters, it has been tested on 1 phase, 2 string inverter version such as my MIN 3000 TL-XE, MIC 1500 TL-X, MIC 600 TL-X. You find attached to this repo the documentation I used to get data out of the inverter.
In addition it supports an AHT10, AHT15, AHT20 sensor family temperature sensor. A web interface for monitoring and controlling the inverter is also available.
This sketch publishes the following information from the holding registers that store device configuration data. More on these please refer to the modbus PDF documentation. This is sent once at startup: Enable state, SaftyFuncEn, Inverter Max output active power percent, Inverter max output reactive power percent, Normal work PV voltage, Firmware version, Control Firmware version, Serial number, Grid voltage low and high limit protect, Grid frequency low and high limit protect
The sketch also publishes the live statistics every 4 seconds. These are stored in the input registers: Inverter run state, Input power, PV1 and PV2 voltage current and power, Output power, Grid frequency, Energy generated today and total and these for both PV1 and PV2, 3 temperatures, Inverter output PF now, Derating mode, Fault and warning codes.
Download this repository and build and flash your ESP. As I said the code works for 1 phase 2 string inverters, if you have a 3 phase inverter, or more strings the code will still work, but you will not see all the data in the device. For BOM and PCB scroll down for the relevant sections below. You need an Arduino IDE with ESP8266 configuration added. You need a few additional libraries (see below). And before you build open the settings.h and set your credentials. I think they are self explanatory. Compile and upload.
For MIN solar inverters, you need to use the SYS COM port on the underside of the unit. The special connector is supplied with the inverter.
Disassemble the connector (see instructions in the user manual) and use PIN3 and PIN4 for the modbus connection. It is PIN3 for RS485A1 and PIN4 for RS485B1. The pin numbers are clearly labeled on the connector inside. RS485A1 connects to the A pin (green screw terminal) on the RS485toTTL board and RS485B1 connects to B. I used a pair of thin wires from a CAT5 network cable.
The following libraries are used beside the "Standard" ESP8266 libraries:
- ModbusMaster by Doc Walker
- ArduinoOTA
- SoftwareSerial
- AHT10 (Performance20: added support of AHT10 temperature+humidity sensor used in my hardware implementation)
- ESPConnect
If Wifi ist not configured, ESP starts in AP mode and a captive portal will be provided using http://192.168.4.1 as URL in your Browser. Connect to the AP (SSID: Growatt2MQTT, no passsword), select your SSID and enter password. SSID and Password will be stored in eeprom. To reset the Wifi credentials, change minimum one of the numbers in globals.h (EE_INIT_PATTERN), compile and load firmware again.
the topicroot can be changed in the settings.h file (default is growatt).
BREAKING CHANGE: now data and settings values are provided as individual topics (earlier versions provided the data as one json oject)
| topic | direction | value | function |
|---|---|---|---|
| topicroot/status | publish | send status of the ESP8266 | |
| topicroot/data | publish | send power state of the growatt as single data tracks | |
| topicroot/error | publish | send error state | |
| topicroot/connection | publish | send connection state of the ESP8266 uses the last will of the broker | |
| topicroot/settings | publish | send settings from growatt as single data tracks | |
| topicroot/write/getSettings | subscribe | ON | initializes the resending of the settings |
| topicroot/write/setEnable | subscribe | ON/OFF | enable/disable the output of the growatt |
| topicroot/write/setMaxOutput | subscribe | 0-100 | set the output level of the growatt in percent |
| topicroot/write/setStartVoltage | subscribe | set the minimum voltage oft the MPPT tracker | |
| topicroot/write/setModulPower | subscribe | HEX | change the type of inverter. see chapter ModulPower command |
| topicroot/writeconfig/setStatusUpd | subscribe | 1- 65535 | status meassage send period in sec |
| topicroot/writeconfig/setWifiCheck | subscribe | 1- 65535 | check if wifi is connected, period in sec |
| topicroot/writeconfig/setModbusUpd | subscribe | 1- 65535 | read register values via modbus, period in sec |
Read or change the type of inverter. e.g. MIC 600TL-X to MIC 1000TL-X.
Make sure that the data sheets of the two devices match, then it is probably the same hardware.
| Value | Powerstage |
|---|---|
| 06 | 600W |
| 07 | 750W |
| 0A | 1000W |
| 0F | 1500W |
| 14 | 2000W |
| 19 | 2500W |
| 1E | 3000W |
Danger! Can lead to the destruction of the inverter.
In order to be able to execute SetModulPower, must be add #define useModulPower 1 in settings.h.
I designed a custom PCB for this board (for a previous project), you can order if from here: https://www.pcbway.com/project/shareproject/ESP8266_Modbus_board.html
These are the components you need to build this. I purchased most of them a long time ago. I don't have the original listing, so I included a similar Aliexpress listing.
- Wemos D1 mini
- RS485 to TTL converter: https://www.aliexpress.com/item/1005001621798947.html (also works with 3.3V)
With these two components you can power the board using the micro USB on the Wemos D1 mini. My PCB includes components for mains supply:
- Hi-Link 5V power supply (https://www.aliexpress.com/item/1005001484531375.html) the power can be also delivered by the USB connection of the Growatt
- Fuseholder and 1A fuse
- Optional varistor
- 5.08mm pitch KF301-2P screw terminal block
For a different Modbus project, I have designed a slightly different board:
The difference of this board:
- Components for the mains input removed (Hi-Link power supply, fuse, varistor) and it has a +5V input from an external power course, or a footprint for a small DC-DC buck converter if powered from more 9-25V.
- Added a specific pad for a neopixel modul for visual feedback.
Rest is the same.
- 4 pin DC-DC buck converter power supply module. The module I used looks like is no longer available, but I found a similar module: https://www.aliexpress.com/item/1005003512429148.html. This is configurable for different voltages with solderpads in the back, but the default is 5V.
- WS2812 Neopixel module: https://www.aliexpress.com/item/33026835790.html. This is optional, the sketch works without the neopixel as well
To make this project work (modbus communnication and the web bits (MQTT, HTTP) you can use both of my version 1 (https://www.pcbway.com/project/shareproject/ESP8266_Modbus_board.html) and version 2 (https://www.pcbway.com/project/shareproject/Modbus_to_MQTT_board_version_2_338ed64e.html) modbus PCB modules as well. I explained the differences between them in the version 2 PCBWay project page and also in the video. Feel free to order and of the modules and the same code will work on both.
And if you want to wire them yourself, these are the connections:
Wemod D1 mini (or other ESP) TTL to RS485
D0 DE
D7 RE
D5 RO
D6 DI
5V VCC
G(GND) GND
Wemod D1 mini (or other ESP) AHT Temperature Sensor
D1 SCL
D2 SDA
Please adapt the Pin Definitions in the settings.h
| GET/POST | URL | Description |
|---|---|---|
| GET | / | Inverter Status and Settings |
| GET | /modbus | last readout of Modbus Input and Holding Registers |
| GET | /api/limit/percent | get active power Limit of Inverter |
| POST | /api/limit/percent | set active power Limit of Inverter to Values between 1 and 100 % |
| GET | /api/onoff | get Inverter power state (0-off, 1-on) |
| POST | /api/onoff | set Inverter power state (0-off, 1-on) |
In general: If you dont want to control your inverter through the webAPI, remove line #define ENABLE_WEBAPI_POST in settings.h
| Command | curl request |
|---|---|
| Limit Inverter to 50% | curl -v http://<yourIPAdress>/api/limit/percent -d '50' |
| Switch Inverter on | curl -v http://<yourIPAdress>/api/onoff -d '1' |
| Return Code | Description |
|---|---|
| 200 | Operation successful |
| 404 | Wrong request i.e. parameter out of range or not provided |
| 500 | failed to set Value |
I have a few videos covering the development of this project:
