Fronius

Sysmo

Enabling Modbus TCP (SunSpec) on Fronius Inverter

1. Access the inverter's local web interface Connect to your local network and enter the inverter's IP address in your browser. This opens the Fronius web interface.

2. Go to Settings → Modbus In the left-hand menu, click MODBUS.

3. Enable Modbus TCP data transfer Under "Gegevensoverdracht via Modbus" (Data transfer via Modbus), select tcp.

4. Set the SunSpec Model Type Under "Sunspec Model Type," select int + SF (integer + scale factor). This is the standard SunSpec register format most third-party EMS platforms — including ours — expect.

5. Verify the Modbus port The default Modbus port is 502. Leave this unless your network setup requires a different port.

6. Enable inverter control via Modbus Make sure the checkbox "Inverterbesturing via Modbus" (Inverter control via Modbus) is checked. This allows the EMS to send control commands (curtailment, setpoints, etc.), not just read data.

7. Confirm and save Click the checkmark (✓) icon top-right to save the settings.

8. Enable data logging during night hours Go to FRONIUS SOLAR.WEB in the left menu, and under "Datalogging tijdens de nachturen" (Data logging during night hours), select Ja (Yes). This prevents the inverter from powering down its communication interface overnight, which would otherwise cause the EMS to lose connection during nighttime hours.

9. Save these settings too with the ✓ icon.