Fronius: Read / Change settings via network: Modbus

For direct API access to the Fronius inverter, Modbus can be used as an alternative to the Rest-API interface (Solar-API). Modbus TCP enables data to be read out via the network and certain settings to be changed. For example, Modbus can be used to intervene in the charging behavior of the battery, see: Controlling Fronius and BYD batteries via modbus

Activate the interface on the inverter

Before Modbus can be used, the interface on the inverter must be activated as the "Technician" user: Menu item: Communication / Modbus:

If the terms: "Master" / "Slave" are used in the GUI, the firmware is not up to date. The terms have been renamed to "Modbus Client and "Modbus Server".

For reference: my installed components:

Connect Home Assistant via SunSpec

Sunspec is an open standard for reading energy data. The "SunSpec" HACS repository of the same name makes it possible to query data from the inverter via Modbus:

Software	Ha-sunspec
GitHub	https://github.com/cjne/ha-sunspec
current version	0.0.26
found	2024-08-20

After adding the repository, the associated integration should be able to be added:

The wizard allows you to add a specific prefix for the PV system components found:

Conclusion

Compared to the Solar API, the Modbus interface provides even more data and can also be used to control the PV system. See also: Controlling Fronius and BYD batteries via Modbus.