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This wiki covers the Fronius Modbus Home Assistant integration. It reads Fronius GEN24 and Verto inverters, their smart meters and their battery over Modbus TCP (SunSpec), and controls the battery and the inverter's output limits. A login to the inverter's local Web API is optional: it sets up the inverter's Modbus for you and adds battery settings Modbus does not carry. The inverter's web interface also reports module temperatures, fans, battery health and the inverter's event log, without a login.
It began as redpomodoro/fronius_modbus and continued here. Version 1.0 is a rewrite onto Home Assistant's shared Modbus connection. Entries, entity IDs and history of the 0.3.x releases carry over, except the module sensors when coming straight from 0.2.7 or older (see Migration).
- Developed on a Symo GEN24 10.0 with a BYD Battery-Box Premium HV and a Fronius Smart Meter TS 65A-3, and also confirmed on a Verto 30.0 Plus with a Fronius Reserva battery.
- Users ran the earlier 0.3.x versions on other models as well, such as other Symo and Primo GEN24, Verto Plus, BYD Battery-Box batteries, and Smart Meter TS 100A-1 and 63A. The 1.x code discovers each device through SunSpec and should work on them too.
- Tauro models (Tauro ECO included) should work the same way but have no reports yet; Fronius publishes the same SunSpec register maps for them, without the storage model.
- Older inverters with a Datamanager (the SnapINverter family: Symo,
Primo, Eco, Galvo without GEN24) are untested. Their Web API has other
logins and paths, so they can only be set up Without the web API, with
the Datamanager's Modbus set to the
int+SFmodel type. - Keep the inverter's firmware up to date; the integration is only tested on recent firmware.
Requires Home Assistant 2026.9.0 or newer.
| Page | Content |
|---|---|
| Installation and Setup | Prerequisites at the inverter, installation, discovery, setup, options, removal |
| Web API | The two roles, what the login does and adds, the stored token, running without it |
| Entities | Every entity with its English and German name, source, unit and range |
| Battery Control | Storage modes, the Modbus and Web API battery controls, the two minimum SoC values, charging from the grid, the inverter controls |
| Events and Throttling | The inverter's event log, the throttle reason |
| How Data Updates | The Modbus and Web API polls, writes, outages, reloads |
| Examples | Automations for dynamic prices, negative prices and notifications |
| Troubleshooting and Diagnostics | Error messages, repair notices, logs, diagnostics, the dump tool, known limitations |
| Migration | Coming from 0.3.x, redpomodoro or an older entry |
Unless a sentence says it was seen on an inverter or comes from Fronius' documents, it describes how the integration behaves. Observations come from a GEN24 and, where stated, a Verto; another model or firmware may behave differently. Reports from other models are welcome as an issue.
Reference from Fronius: operating instructions 42,0410,2649 (PDF).
This is an unofficial implementation, not supported by Fronius. Use is at your own risk.