KNX gateway for SMA Inverters
KNX gateway for SMA Sunny Boy and Sunny Tripower inverters enabling real-time solar production monitoring on KNX. Transfers AC/DC power data via Modbus TCP over Ethernet for energy optimization and building automation integration.
Overview
The INV-KNX-SMA is a professional KNX gateway designed for seamless integration of SMA Sunny Boy and Sunny Tripower 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 SMA inverters using the SMA SunSpec Modbus interface over Ethernet (RJ45). 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 SMA 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 |
| 26 | AC Frequency | AC frequency |
| 27 | AC VA | AC apparent power |
| 29 | AC PF | Power factor |
| 30 | AC Energy | Total AC energy yield |
| 32 | Insulation | Insulation resistance |
| 33 | Temperature | Cabinet temperature |
| 41 | Battery 1 Running Status | 0=Off, 6=Discharging, 7=Charging, 8=Float charge |
| 43 | Battery 1 SOC | Battery state of charge (%) |
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). The Modbus TCP connection requires the inverter IP address, port 502, and Unit ID 126 (corresponding to SMA Unit ID 3 with +123 offset). On the SMA inverter, Modbus TCP Server must be enabled via Sunny Explorer.
ETS configuration includes AC network type selection (single/three-phase), PV circuit count (1-4), refresh rate, and battery monitoring options. 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.
Commercial buildings leverage the gateway for energy management dashboards showing real-time solar contribution, grid import/export balance, and efficiency metrics. Integration with KNX HVAC control enables thermal storage optimization during peak solar production.
Self-consumption optimization scenarios use AC power 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-SMA is compatible with SMA Sunny Boy and Sunny Tripower inverter series supporting the SMA SunSpec Modbus interface. 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.
