Victron ESS Mode 2 and 3 Setup Guide
Updated 6 September 2026 · By SolarNevs Research Desk, Dealer surveys + verified sources · 1 source · Method ↗
Key Takeaways
- Victron ESS Mode 2 and Mode 3 are for advanced external control of your energy system.
- You need a Multi/Quattro inverter and a GX device to use these modes.
- Control is primarily through ModbusTCP, MQTT, or D-Bus scripts on the GX device.
- Victron Energy does not offer direct support for custom implementations of these features.
How do I set up Victron ESS Mode 2 and Mode 3?
Setting up Victron ESS Mode 2 and Mode 3 involves configuring external control points to manage your energy storage system. These modes allow an external system to dictate how your Victron Multi/Quattro inverter interacts with the grid and manages battery charging and discharging. The core components required are a Victron Multi/Quattro bidirectional inverter and a GX device, which acts as the communication gateway.
Understanding Victron ESS Mode 2 and Mode 3 Control
Victron ESS Mode 2 and Mode 3 provide programmatic interfaces for advanced system control. Mode 2 offers granular control over various aspects of the ESS, such as grid power setpoints and inverter/charger enable/disable functions. Mode 3 provides a more direct control over the Multi/Quattro's operational state and power setpoint.
These control points can be accessed through several methods:
- ModbusTCP: This protocol allows external systems to read and write values to specific registers on the GX device. The ModbusTCP unit ID for ESS control is 100.
- MQTT: A lightweight messaging protocol available both on a local broker on the GX device and remotely via a secure cloud connection.
- D-Bus Scripts: Custom scripts can be run directly on the GX device to interact with specific D-Bus paths, offering another layer of control.
Victron Energy notes that they do not offer support for professional customers or end-users who implement features using these documented functionalities, except in specific situations.
Victron ESS Mode 2 Control Points
ESS Mode 2 provides a range of ModbusTCP registers to control the system's behavior. These registers allow you to set grid power, enable or disable charging and inverting, and define maximum power limits.
Setting Name | Values | Protocol |
|---|---|---|
Grid power setpoint | Positive: take power from grid; Negative: send power to grid; Default: 50 W | ModbusTCP register 2716 (Venus 3.50+), 2700 (before Venus 3.50), 2703 (before Venus 3.50 for larger range) |
Enable/Disable charge | 0: disable charging; 100: unlimited charging | ModbusTCP register 2705 (recommended), 2701 (deprecated) |
Enable/Disable inverter | 0: disable inverter; 100: enabled inverter | ModbusTCP register 2704 (recommended), 2702 (deprecated) |
Maximum inverter power | -1: No limit; Any positive number: Maximum power in Watt | ModbusTCP register 2704 |
DVCC maximum system charge current | -1: No limit; Any positive number: Maximum combined current in Ampere | ModbusTCP register 2705 |
Maximum system grid feed-in | -1: No limit; Any positive number: Maximum power in 100 Watt units | ModbusTCP register 2706 |
Feed excess DC-coupled PV into the grid | 0: Not fed; 1: Fed | ModbusTCP register 2707 |
Feed excess AC-coupled PV into the grid | 0: Fed; 1: Not fed (inverted logic) | ModbusTCP register 2708 |
Grid limiting status | 0: Not limited; 1: Limited | ModbusTCP register 2709 |
These registers allow for dynamic control. For example, you can set a positive grid power setpoint to draw power from the grid, or a negative value to feed power back. The DVCC maximum system charge current register allows you to limit the total charge current for the entire system.
Victron ESS Mode 3 Control Points
ESS Mode 3 offers a more simplified set of control points, focusing on the operational state of the Multi/Quattro and a direct power setpoint.
Setting Name | Values | Protocol |
|---|---|---|
Switch | on, charger-only, inverter-only, off | External command |
Power setpoint | Watts (regulates power on AC-input) | External command |
The Switch control allows you to change the operational mode of the Multi/Quattro, while the Power setpoint directly regulates the power on the AC input in Watts.
D-Bus Paths for Scripting
For those developing custom scripts on the GX device, specific D-Bus paths are available to interact with ESS settings. These paths correspond to various control points, allowing for advanced automation and integration.
-
/Settings/CGwacs/AcPowerSetPoint(Grid power setpoint) -
/Settings/CGwacs/MaxChargePercentage(Enable/Disable charger) -
/Settings/CGwacs/MaxDischargePercentage(Enable/Disable inverter) -
/Settings/CGwacs/MaxDischargePower(Maximum inverter power) -
/Settings/SystemSetup/MaxChargeCurrent(DVCC maximum charge current) -
/Settings/CGwacs/MaxFeedInPower(Maximum system grid feed-in of excess power)
These D-Bus paths provide a direct interface for scripts to read and modify ESS parameters, enabling highly customized control logic.
Safety
When working with any electrical system, including Victron ESS, safety is paramount. Always follow general electrical safety practices.
- Isolate Power: Before making any physical connections or adjustments, ensure all power sources, including PV, battery, and AC breakers, are fully isolated.
- Insulated Tools: Use insulated tools to prevent accidental short circuits.
- Professional Installation: If you are unsure about any aspect of the setup or configuration, consult a qualified solar technician.
No specific safety facts are detailed in the provided documentation for ESS Mode 2 and 3 beyond general installation guidelines.
When to call a technician instead
Implementing Victron ESS Mode 2 and Mode 3 requires a strong understanding of ModbusTCP, MQTT, or D-Bus scripting, as well as the Victron Energy system architecture. If you encounter difficulties with programming, network configuration, or if the system does not behave as expected after configuration, it is advisable to contact a qualified solar technician. Victron Energy explicitly states that they do not offer support for custom implementations of these advanced features, so direct manufacturer support for your specific script or external control system may not be available. A technician can help diagnose complex issues and ensure your system operates safely and efficiently.
Frequently asked questions
What are Victron ESS Mode 2 and Mode 3?
Victron ESS Mode 2 and Mode 3 are advanced operating modes that allow external systems to control your Victron Energy Storage System. They provide control points for managing grid power flow, charging, and inverting functions.
What equipment is required for Victron ESS Mode 2 or Mode 3?
To implement Victron ESS Mode 2 or Mode 3, you need a Victron Multi/Quattro bidirectional inverter and a GX device. The GX device acts as the central communication hub for these control modes.
How can I control Victron ESS in Mode 2 or Mode 3?
You can control Victron ESS in Mode 2 or Mode 3 using ModbusTCP, MQTT (either locally on the GX device or via a secure cloud connection), or by running custom scripts on the GX device that access D-Bus paths.
Does Victron Energy provide support for custom ESS Mode 2 and 3 implementations?
Victron Energy states that they do not offer direct support for professional customers or end-users who implement features using these advanced functionalities, except in specific situations.
What is the ModbusTCP Unit ID for ESS control?
When using ModbusTCP for ESS control, the required Unit ID is 100.
References
- Victron ESS Mode 2 and 3 Documentation — accessed 23 August 2026
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