Python script to control Hoymiles HM inverters

This script was designed for zero export control (aka "Nulleinspeisung") of Hoymiles inverters in connection with with a Rasperry Pi, an nRF24L01+ board and a Shelly 3EM.

It is mainly based on the work of: https://github.com/Knedox/hoymiles_control

Parts needed

• Hoymiles HM-* inverter (tested with Hoymiles HM-300, HM-400 and HM-600, but any should work)
• Raspberry Pi (tested on a Raspberry Pi 1B, any should work)
• nRF24L01+ module
• 7 jumper wires
• Shelly 3EM

Prerequisites

• Properly installed Shelly 3EM with connection to your home network
• Working Hoymiles HM-* inverter
• Working Raspberry Pi with Raspberry Pi OS and connection to your home network

Setup

• Connect the nRF24L01+ module to your Rasperry Pi as follows:

nRF		Pi
1	GND	20	GND
2	VCC	17	+ 3,3V
3	CE	15	GPIO 22
4	CSN	24	GPIO 8
5	SCK	23	GPIO 11
6	MOSI	19	GPIO 10
7	MISO	21	GPIO 9
8	IRQ	N/A	not needed

• Enable SPI interface in sudo raspi-config

• Install required software on Raspberry Pi:

sudo apt update && sudo apt install -y python3-pip
pip3 install circuitpython-nrf24l01 Adafruit-Blinka crcmod

• Download this repository and edit the configuration file hm_control_config.py (you need to adjust at least hm_control_cfg_inverter_ser and hm_control_cfg_shelly3em to match your conditions)

• Upload all files from this repository to your Raspberry Pi (e.g. to /home/pi/) and make hm_control.py executable:

chmod +x hm_control.py

Usage

You can run the script with an optional parameter. If you run the script without a parameter, the initial power limit will be set to hm_control_cfg_inverter_power_min. If you run the script like

./hm_control.py 150

the initial power limit is set to 150 W.

Setting an initial power is needed as the script doesn't know the current power limit of the inverter (but this is necessary for further operation). Afterwards the power limit is set according to the parameters in the configuration file.

Autostart

In order to start the script on each (re)boot of your Raspberry Pi you should add it to your crontab. To get access to the output easily I recommend to use screen in your cronjob.

Install screen:

sudo apt update && sudo apt install -y screen

Add the following line to your crontab (crontab -e):

@reboot (cd /home/pi/; sleep 10; /usr/bin/screen -dmS hoymiles_zero_export ./hm_control.py)

You can use screen -r at any time to reattach to the screen session. Keep in mind to use the key sequence CTRL+A + CTRL-D to detach from the screen session (this will keep the script running in background).