Victron Fronius Integration: Modbus TCP Setup
Updated 16 September 2026 · By SolarNevs Research Desk, Dealer surveys + verified sources · 1 source · Method ↗

Key Takeaways
- Grid-tied power regulation: The Fronius Zero feed-in feature - which is part of an Energy Storage System ESS - works on all supported models except the IG Plus.
- Active Venus OS power throttling: It is possible to make a Zero feed-in system with Victron & Fronius. the Venus (GX) device controls the Fronius output power.
- Automated network discovery: The GX Device will automatically scan for PV-inverters on the local network if no PV-inverters were found previously or if a previously-found PV-inverter cannot be contacted.
- Inverter system placement: Configure the position relative to the Multi or Quattro (is it: AC Input / AC Output).
- Polyphase output assignment: Configure the phase for each inverter in the list.
- Datamanager hardware configuration: Make sure the “IP Switch” on the Fronius Datamanager is on position “A”.
- Network infrastructure link: Connect both, the Fronius and the GX Device, on the same LAN network, either directly with a LAN cable or using a network switch.
- Modbus export protocol: **Set Data export via Modbus to tcp.
- SunSpec register format: set Sunspec Model Type to int + SF.
- Off-grid microgrid synchronization: To make sure that the Fronius PV inverter works well with Victron inverter/chargers, both must be configured with the right 'frequency shift settings'.
SunSpec Modbus TCP Architecture & Network Configuration
Integrating Fronius PV inverters (Primo, Symo, Eco) with Victron GX controllers allows comprehensive energy monitoring, ESS zero-export power control, and synchronized off-grid microgrid operation.
The Victron & Fronius Inverter Integration utilizes SunSpec Modbus TCP Protocol (Port 502) with SunSpec Model Type: int + SF, providing Dynamic Zero Feed-In (ESS) and Frequency Shift Droop (Island) control:
- Fronius Datamanager: IP Switch on "A", Modbus TCP Export, int + SF Register, Ethernet / WiFi LAN.
- Network Discovery: Auto Scan on LAN, AC-in / AC-out Pos, Phase L1/L2/L3 Map, VRM Dashboard.
- Power Control: Venus Throttl, Zero Feed-in, Freq Shift Droop, ESS Dynamic.
Installation Rules & Network Setup
- Local Network Connection: Ensure you Connect both, the Fronius and the GX Device, on the same LAN network, either directly with a LAN cable or using a network switch. and verify Make sure the “IP Switch” on the Fronius Datamanager is on position “A”.
- SunSpec Protocol Configuration: Log into the Fronius web portal and Set Data export via Modbus to tcp. ensuring you set Sunspec Model Type to int + SF.
- GX Device Scanning: Verify The GX Device will automatically scan for PV-inverters on the local network if no PV-inverters were found previously or if a previously-found PV-inverter cannot be contacted.
Inverter Topology & Phase Mapping
Within the Venus OS interface:
- System Positioning: Installers Configure the position relative to the Multi or Quattro (is it: AC Input / AC Output).
- Phase Alignment: Accurately Configure the phase for each inverter in the list to guarantee correct multi-phase energy accounting.
Dynamic Zero Feed-In & Frequency Shifting
- ESS Zero-Export Control: Functions because The Fronius Zero feed-in feature - which is part of an Energy Storage System ESS - works on all supported models except the IG Plus. where It is possible to make a Zero feed-in system with Victron & Fronius. the Venus (GX) device controls the Fronius output power.
- Off-Grid Frequency Droop: Safeguards islanded batteries since To make sure that the Fronius PV inverter works well with Victron inverter/chargers, both must be configured with the right 'frequency shift settings'.
Technical Specifications & Parameter Summary
Parameter | Engineering Setting | Operational Role |
|---|---|---|
Zero Export Capability | The Fronius Zero feed-in feature - which is part of an Energy Storage System ESS - works on all supported models except the IG Plus. | Dynamic grid feed-in limitation in ESS |
Venus Power Control | It is possible to make a Zero feed-in system with Victron & Fronius. the Venus (GX) device controls the Fronius output power. | Direct Modbus active power throttling |
Network Discovery Scan | The GX Device will automatically scan for PV-inverters on the local network if no PV-inverters were found previously or if a previously-found PV-inverter cannot be contacted | Automatic local network inverter detection |
System Position Option | Configure the position relative to the Multi or Quattro (is it: AC Input / AC Output) | Defines power flow direction in VRM |
Phase Configuration | Configure the phase for each inverter in the list | Maps inverter output to system phases |
Datamanager Hardware Switch | Make sure the “IP Switch” on the Fronius Datamanager is on position “A” | Enables dynamic DHCP network addressing |
LAN Interconnection | Connect both, the Fronius and the GX Device, on the same LAN network, either directly with a LAN cable or using a network switch. | Ethernet backbone for Modbus communications |
Modbus Export Setting | Set Data export via Modbus to tcp. | Activates Modbus TCP server on port 502 |
SunSpec Register Model | set Sunspec Model Type to int + SF | Standardized integer scale factor registers |
Frequency Shift Sync | To make sure that the Fronius PV inverter works well with Victron inverter/chargers, both must be configured with the right 'frequency shift settings' | Over-frequency solar curtailment in island mode |
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Frequently asked questions
What communication protocol and hardware settings are required on Fronius inverters for Victron GX integration?
Connect the Fronius inverter and the GX device to the same LAN, either directly with a LAN cable or via a network switch (August 2026). Set the “IP Switch” on the Fronius Datamanager to position “A”, then in the inverter web interface set Data export via Modbus to **tcp** and the Sunspec Model Type to **int + SF.
How does the Victron GX device discover and configure Fronius inverters?
The GX Device will automatically scan for PV-inverters on the local network if no PV-inverters were found previously or if a previously-found PV-inverter cannot be contacted**, allowing installers to Configure the position relative to the Multi or Quattro (is it: AC Input / AC Output) and **Configure the phase for each inverter in the list** (August 2026).
How are dynamic zero feed-in and off-grid frequency shifting implemented?
In a grid-tied ESS, Fronius Zero feed-in works on all supported models except the IG Plus: the GX (Venus) device directly controls the Fronius output power (August 2026). In islanded (off-grid) operation, both the Fronius inverter and the Victron inverter/charger must instead be configured with matching frequency-shift settings.
References
- Victron Energy: AC-coupled PV with Fronius PV Inverters Manual — accessed 31 August 2026
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