KNX gateway for Fronius Inverters
KNX gateway for Fronius inverters enabling real-time solar production monitoring on KNX. Transfers comprehensive AC/DC power and energy data via Modbus TCP over Ethernet for intelligent energy management and building automation integration.
Overview
The INV-KNX-FR is a professional KNX gateway designed for seamless integration of Fronius solar inverters into KNX building automation installations. This interface enables real-time transfer of all relevant inverter data to the KNX bus via Modbus TCP over Ethernet, allowing integrators to implement intelligent energy management, consumption optimization, and automated building responses based on solar production.
Technical Capabilities
The gateway communicates with Fronius inverters using the SMA SunSpec Modbus interface over Ethernet (RJ45). All Fronius inverters with SetApp configuration are SunSpec-supported, as well as inverters with LCD that have firmware version 3.xxxx and above. The gateway supports both Fronius Gen24 series (model setting 3) and Fronius Symo Hybrid inverters (model setting 6). Data is polled at a configurable refresh rate (1-255 minutes) and transmitted to the KNX bus through dedicated group objects. The device supports both single-phase and three-phase AC network configurations.
Inverter Communication Objects
The following KNX group objects are available for monitoring Fronius inverter data:
| GO | Name | Description |
|---|---|---|
| 3 | AC Current | AC Total Current value |
| 4 | AC Current A | AC Current phase A |
| 5 | AC Current B | AC Current phase B |
| 6 | AC Current C | AC Current phase C |
| 8 | AC Voltage AB | AC Voltage phase AB |
| 9 | AC Voltage BC | AC Voltage phase BC |
| 10 | AC Voltage CA | AC Voltage phase CA |
| 11 | AC Voltage AN | AC Voltage phase AN |
| 12 | AC Voltage BN | AC Voltage phase BN |
| 13 | AC Voltage CN | AC Voltage phase CN |
| 16 | PV1 Voltage | PV string 1 voltage |
| 17 | PV1 Current | PV string 1 current |
| 18 | PV2 Voltage | PV string 2 voltage |
| 19 | PV2 Current | PV string 2 current |
| 24 | AC Power | AC Power output |
| 25 | DC Power | DC Power |
| 26 | AC Frequency | AC Frequency |
| 27 | AC VA | AC Apparent power |
| 28 | AC VAR | AC Reactive power |
| 29 | AC PF | Power factor |
| 30 | AC Energy | Total AC Energy |
| 41 | Battery 1 Running Status | 0: OFF, 1: EMPTY, 6: DISCHARGING, 7: CHARGING, 9: FULL, 10: HOLDING, 11: TESTING |
| 43 | Battery 1 SOC | Battery state of charge (%) |
| 55 | Powermeter | Fronius Smart Meter (meter Modbus ID configured in ETS) |
The gateway includes a built-in KNX logic module supporting up to 64 configurable logic functions including logic gates with 8 inputs, 4-step sequences, triggers with weekly calendar events, and math operations for advanced energy calculations.
Installation and Configuration
The compact 2 SU DIN-rail module requires an external 12-30VDC power supply connected via screw terminal. The Ethernet connection to the inverter network uses a standard RJ45 connector. The KNX bus connects via a pluggable micro terminal with push-wire connection for 0.6-0.8mm solid conductor wire.
Network configuration is performed via the built-in web interface (default IP: 192.168.1.51). Configure Modbus TCP in Connect mode with the Fronius inverter IP address, port 502, and Unit ID 1. On the Fronius inverter, Modbus TCP must be enabled via the Fronius Datamanager web interface with data export set to TCP, port 502, and Sunspec model type set to int+SF.
ETS configuration includes AC network type selection (single/three-phase), inverter model selection (3 for Gen24 or 6 for Symo Hybrid), refresh rate, and battery monitoring options. If a Fronius Smart Meter is installed, enable the Powermeter option and configure the meter Modbus ID in the Device Options field (typically 200 or 240). The free ETS Demo version is fully supported.
Applications
Residential solar installations benefit from real-time production monitoring displayed on KNX visualization panels. Automation scenarios can trigger load activation (EV charging, water heating, pool pumps) when solar generation exceeds consumption thresholds. Battery state-of-charge monitoring enables intelligent backup power management with Fronius hybrid systems.
Commercial buildings leverage the gateway for energy management dashboards showing real-time solar contribution, grid import/export balance via the Fronius Smart Meter, and efficiency metrics. Integration with KNX HVAC control enables thermal storage optimization during peak solar production.
Self-consumption optimization scenarios use AC power and power meter data to automatically route surplus solar energy to controllable loads before grid export, maximizing on-site consumption and reducing electricity costs.
Compatibility and Integration
The INV-KNX-FR is compatible with Fronius inverters supporting the Modbus interface, including all SetApp-configured inverters and LCD-equipped inverters with firmware version 3.xxxx or above. Supported series include Fronius Gen24, Fronius Symo, Fronius Symo Hybrid, and Fronius Primo. The gateway integrates with any KNX TP installation and is fully configurable using ETS5 or ETS6, including the free ETS Demo version.
The device provides galvanic isolation between the KNX bus and the Ethernet/inverter circuitry. Firmware updates are available via the built-in web interface. The gateway follows the unified Elausys inverter gateway architecture, ensuring consistent integration patterns with HyperVisu visualization servers and other KNX system components.
