How to Build a Custom Victron Energy MQTT Dashboard — Free, No Install

Why Build a Custom Victron Dashboard?

If you own a Victron Energy system — whether it's a home ESS, off-grid cabin, marine setup, or RV — you're already sitting on a goldmine of real-time data. Your Cerbo GX, Venus GX, or Raspberry Pi running Venus OS publishes hundreds of MQTT topics every second:

• Solar PV: power (W), voltage (V), current (A), daily yield (kWh), MPPT tracker state
• Battery: state of charge (%), voltage, current, power, temperature, time-to-go
• Grid / AC: grid power, voltage, frequency, AC consumption, import/export
• Inverter: MultiPlus/Quattro state, AC output, alarms, relay status
• System: ESS mode, generator status, tank levels, GPS position

The Victron VRM portal shows some of this data, but it's delayed, not customizable, and you can't add your own logic. Node-RED and Grafana are powerful but require a server, Docker, and significant setup time. Home Assistant is an entire home automation platform when you might just want a clean energy dashboard.

What You Need

Before we start, here's the checklist:

That's it. No server to set up, no packages to install, no Docker compose files. Let's build.

Step 1: Enable MQTT on Your Venus OS

On your Cerbo GX (or other Venus OS device):

1. Navigate to Settings → Services → MQTT
2. Toggle MQTT to Enabled
3. Note your device's IP address (e.g., 192.168.1.100)
4. The WebSocket port is 9001 by default

Step 2: Open WebVB Studio

Go to app.webvbstudio.com. No account needed, no sign-up, nothing to download. The IDE loads in your browser with a visual form designer, a toolbox of 25+ controls, and a code editor.

You can start from the MQTT IoT Dashboard example (available in the Examples menu) or build from scratch. For this guide, we'll build from scratch so you understand every piece.

Step 3: Design Your Dashboard Layout

This is where WebVB Studio shines — you design visually. From the toolbox, drag these controls onto your form:

A typical Victron dashboard might have:

• 3 Gauges — Battery SOC (%), Solar Power (W), Battery Voltage (V)
• 1 Chart — Solar production timeline throughout the day
• 4–6 Labels — Grid power, AC consumption, inverter state, system mode
• 1 MQTT control — for the broker connection

Arrange them however you like. Resize, align, and position controls by dragging. No CSS, no layout managers, no grid-template-columns.

Step 4: Write the MQTT Event Handlers

Here's where a few lines of code bring everything to life. Switch to the Code tab and choose Python (or VB6 if you prefer). The code is event-driven — you just handle the events that matter.

Python Version

def Form1_Load():
    # Configure the MQTT connection
    Mqtt1.BrokerUrl = "ws://192.168.1.100:9001"

    # Configure gauges
    GaugeSoc.MinValue = 0
    GaugeSoc.MaxValue = 100
    GaugeSoc.Title = "Battery SOC"
    GaugeSoc.Unit = "%"
    GaugeSoc.ThresholdLow = 20
    GaugeSoc.ThresholdHigh = 80

    GaugeSolar.MinValue = 0
    GaugeSolar.MaxValue = 5000
    GaugeSolar.Title = "Solar Power"
    GaugeSolar.Unit = "W"

    GaugeVolts.MinValue = 44
    GaugeVolts.MaxValue = 56
    GaugeVolts.Title = "Battery"
    GaugeVolts.Unit = "V"

def Mqtt1_Connect():
    # Subscribe to key Victron topics
    Mqtt1.Subscribe("N/+/system/0/Dc/Battery/Soc")
    Mqtt1.Subscribe("N/+/system/0/Dc/Pv/Power")
    Mqtt1.Subscribe("N/+/system/0/Dc/Battery/Voltage")
    Mqtt1.Subscribe("N/+/system/0/Dc/Battery/Power")
    Mqtt1.Subscribe("N/+/system/0/Ac/Grid/L1/Power")
    Mqtt1.Subscribe("N/+/system/0/Ac/Consumption/L1/Power")
    lblStatus.Caption = "Connected to Venus OS"

def Mqtt1_Message(topic, payload):
    val = float(payload)

    if "Battery/Soc" in topic:
        GaugeSoc.Value = val
        lblSoc.Caption = f"SOC: {val:.0f}%"

    elif "Pv/Power" in topic:
        GaugeSolar.Value = val
        lblSolar.Caption = f"Solar: {val:.0f} W"
        Chart1.AddPoint("Now", val, "orange")

    elif "Battery/Voltage" in topic:
        GaugeVolts.Value = val
        lblVolts.Caption = f"Battery: {val:.1f} V"

    elif "Grid/L1/Power" in topic:
        lblGrid.Caption = f"Grid: {val:.0f} W"

    elif "Consumption/L1/Power" in topic:
        lblConsumption.Caption = f"Load: {val:.0f} W"

def Mqtt1_Error(err):
    lblStatus.Caption = f"Error: {err}"

That's the entire dashboard. Three event handlers:

• Form1_Load — configures the broker URL and gauge ranges
• Mqtt1_Connect — subscribes to the Victron MQTT topics you care about
• Mqtt1_Message — routes incoming values to the right gauge, label, or chart

VB6 Version

Prefer Visual Basic? The same dashboard in VB6:

Sub Form1_Load
    Mqtt1.BrokerUrl = "ws://192.168.1.100:9001"

    GaugeSoc.MinValue = 0
    GaugeSoc.MaxValue = 100
    GaugeSoc.Title = "Battery SOC"
    GaugeSoc.Unit = "%"
    GaugeSoc.ThresholdLow = 20
    GaugeSoc.ThresholdHigh = 80

    GaugeSolar.MinValue = 0
    GaugeSolar.MaxValue = 5000
    GaugeSolar.Title = "Solar Power"
    GaugeSolar.Unit = "W"
End Sub

Sub Mqtt1_Connect
    Mqtt1.Subscribe "N/+/system/0/Dc/Battery/Soc"
    Mqtt1.Subscribe "N/+/system/0/Dc/Pv/Power"
    Mqtt1.Subscribe "N/+/system/0/Dc/Battery/Voltage"
    Mqtt1.Subscribe "N/+/system/0/Ac/Grid/L1/Power"
    lblStatus.Caption = "Connected to Venus OS"
End Sub

Sub Mqtt1_Message(topic, payload)
    Dim val As Double
    val = CDbl(payload)

    If InStr(topic, "Battery/Soc") Then
        GaugeSoc.Value = val
        lblSoc.Caption = "SOC: " & CStr(CInt(val)) & "%"
    ElseIf InStr(topic, "Pv/Power") Then
        GaugeSolar.Value = val
        lblSolar.Caption = "Solar: " & CStr(CInt(val)) & " W"
    ElseIf InStr(topic, "Battery/Voltage") Then
        lblVolts.Caption = "Battery: " & Format(val, "0.0") & " V"
    ElseIf InStr(topic, "Grid/L1/Power") Then
        lblGrid.Caption = "Grid: " & CStr(CInt(val)) & " W"
    End If
End Sub

Essential Victron MQTT Topics

Venus OS publishes data under the topic pattern N/{portalId}/{service}/{deviceInstance}/{path}. Using + as a wildcard for the portal ID makes your dashboard work with any Victron installation. Here are the most useful topics:

Battery & DC System

Solar / PV

Grid & AC

Advanced Dashboard Features

Once the basics are working, here's how to level up your Victron dashboard:

Low Battery Alerts

def Mqtt1_Message(topic, payload):
    val = float(payload)

    if "Battery/Soc" in topic:
        GaugeSoc.Value = val
        if val < 20:
            lblWarning.Caption = "LOW BATTERY!"
            lblWarning.ForeColor = "red"
            Shape1.FillColor = "red"     # Red warning indicator
        elif val < 50:
            lblWarning.Caption = "Battery moderate"
            lblWarning.ForeColor = "orange"
            Shape1.FillColor = "orange"
        else:
            lblWarning.Caption = "Battery OK"
            lblWarning.ForeColor = "green"
            Shape1.FillColor = "green"

Solar Production Timeline

from datetime import datetime

def Form1_Load():
    Chart1.Title = "Solar Production Today"
    Chart1.ChartType = "1 - Line"

def Mqtt1_Message(topic, payload):
    if "Pv/Power" in topic:
        val = float(payload)
        now = datetime.now().strftime("%H:%M")
        Chart1.AddPoint(now, val, "#f59e0b")

Grid Import/Export Indicator

def Mqtt1_Message(topic, payload):
    if "Grid/L1/Power" in topic:
        val = float(payload)
        if val > 0:
            lblGrid.Caption = f"Importing {val:.0f} W"
            lblGrid.ForeColor = "red"
        elif val < 0:
            lblGrid.Caption = f"Exporting {abs(val):.0f} W"
            lblGrid.ForeColor = "green"
        else:
            lblGrid.Caption = "Grid: 0 W"
            lblGrid.ForeColor = "gray"

Controlling Your Victron System

WebVB Studio can also publish MQTT messages to your Venus OS, allowing you to control your system from your dashboard:

# Switch ESS mode to "Keep batteries charged"
def cmdChargeMode_Click():
    Mqtt1.Publish("W/+/settings/0/Settings/CGwacs/BatteryLife/State", "9")

# Set grid setpoint (target grid power in watts)
def cmdSetpoint_Click():
    Mqtt1.Publish("W/+/settings/0/Settings/CGwacs/AcPowerSetPoint", txtSetpoint.Text)

# Switch inverter on/off
def cmdInverterOn_Click():
    Mqtt1.Publish("W/+/vebus/0/Mode", "3")   # 3 = On

def cmdInverterOff_Click():
    Mqtt1.Publish("W/+/vebus/0/Mode", "4")   # 4 = Off

How Does It Compare to Node-RED, Grafana & Home Assistant?

This is the question every Victron forum thread asks. Here's an honest comparison:

Where WebVB Studio excels: speed of setup, visual form design, zero infrastructure, direct MQTT control. Where it doesn't: it has no built-in data persistence or historical database (yet). If you need weeks of historical Grafana-style graphs with InfluxDB, use Grafana. If you want a live operational dashboard you can build in 10 minutes, WebVB Studio is hard to beat.

Real-World Use Cases

Off-Grid Cabin Monitor

Monitor a remote cabin's MultiPlus inverter, MPPT charge controller, and battery bank. Set alerts for low SOC, high consumption, or generator start. Run the dashboard on a wall-mounted tablet powered by the system itself.

Home ESS Dashboard

Track your grid import/export in real time, visualize self-consumption rate, and watch the energy flow between solar panels, battery, and grid. Add buttons to switch ESS modes or set grid power targets from the dashboard.

Marine & RV Power Panel

Build a compact power panel for your boat or motorhome. Show battery bank status, shore power connection, alternator charge, and solar input. The dashboard works on tablets and phones — mount it on the helm or dashboard.

Installer Multi-Site View

For Victron installers managing multiple sites: connect to different broker URLs and build a summary dashboard that shows the health of every installation at a glance. Compare solar yields across locations and identify underperforming systems.

Troubleshooting Common Issues

Start Building Your Dashboard

Ready to go? Here's the fastest path:

1. Open WebVB Studio — loads instantly, no sign-up
2. Open the MQTT IoT Dashboard example from the Examples menu
3. Change the broker URL to your Venus OS IP: ws://YOUR_IP:9001
4. Click Run — watch live Victron data flow into gauges and charts
5. Customize — add more gauges, change topics, add alerts

Or explore the full Victron Energy dashboard guide with more examples, screenshots, and step-by-step instructions.

Questions? Join the WebVB community or ask on the Victron Community Forum.