Recently trying to interface my FlinEnergy Solar inverter -a Voltronic product, like, Axpert, Mppsolar, PIP, Voltacon, Effekta, and other branded OEM Inverters- I found a few software, but, those failed to interact with my unit. FlinEnergy helped me with the protocol and I found they were using version 18 protocol which was completely different from the protocol used in all the software I tried. This version did not use QPRI and other Q commands, and used the commands starting with ^P0, like ^P005PI <CRC><cr>.
Initial version was based on USB connection to a Raspberry Pi Zero W but that caused the Communication card to get damaged twice, perhaps due to the ground loop. It was then decided to use the serial port as it was isolated. This setup worked fine for over a month till I realized that there was +12V on the RS232 Port that can supply, at least 150mA - FlinEnergy sold me a newer version of the communication board with a bigger transformer on it. So decided to use an ESP8266 that was powered entirely from the Inverter.
The code and schematics are hosted on GitHub - amishv/voltronic_ESP8266_MQTT: Home Assistant addon using MQTT to get data from Voltronic Solar Inverters using ESP8266 with a hope that it may be useful to some users using Protocol 18.
A Dashboard to go with this to display the solar parameter on a Raspberry Pi with TFT or on X86 is hosted on GitHub - amishv/MQTT-Based-Dashboard-for-Solar-Inverter: 'Home Assistant MQTT Sensor' Based Dashboard for Voltronic Solar Inverter..