Locally control immersion heater
Using surplus solar power without a cloud

View facility
View electricity meter

YOUR SYSTEM. YOUR LOGIC. · AS OF AUGUST 2026

Don't just operate – link it yourself

Local integration is aimed primarily at technically proficient users. The immersion heater is connected to a broker in your home network via MQTT.

This allows you to link the control system with your own energy and smart home logic. Which data points and commands are available depends on the current device and firmware version.

This is how data flows through your system

LOCAL ARCHITECTURE

1. The immersion heater is integrated locally.
The novolto immersion heater can receive control commands via MQTT in your home network.

2. An MQTT broker acts as an intermediary.
The broker connects the immersion heater to your own automation system.

3. Your central hub handles the logic.
There, you can incorporate measured values, PV data, and other devices into your own automations.

01 · AUTOMATIONS

Three ideas that are immediately understandable while scrolling

Local control becomes interesting as soon as measured values and devices react together.

  • SURPLUS SOLAR POWER

    Only heat when there is actually excess electricity.

    Use your own surplus value as an enable signal: The immersion heater should only run when sufficient surplus solar power is available.

  • TEMPERATURE

    Hot water on demand instead of by the clock

    If your setup provides the necessary values, you can include temperature, time, or other conditions in your automation.

  • PRIORITIES

    Coordinate battery, wallbox, and hot water

    In your own energy management system, you can determine which appliance receives energy first – for example, battery, wallbox, or hot water.

1 3

What is different locally

MORE FREEDOM

Custom interface: Process MQTT in the system that fits your smart home.

Custom rules: You decide yourself when and under what conditions the immersion heater should react.

Local communication: MQTT messages can be transmitted within your home network.

Important: Which data points and control commands are available depends on the device and firmware.

LOCAL CONTROL

What works today – and what comes next

  • AVAILABLE TODAY

    Local control via MQTT

    Local control via MQTT is already available. To use it, you connect the immersion heater to an MQTT broker on your home network and build your own logic on top of it.

LOCAL DOES NOT MEAN LIMITLESS

Device protection remains important

Custom automations must not bypass temperature limits, safety functions, or installation requirements. Furthermore, plan your control system to account for potential network or broker failure.

02 · SETUP

Four steps to your first own automation

  • 01

    Set up devices regularly

    First, install the immersion heater and power reader completely and check for normal operation.

  • 02

    Configure local interface

    Enter the MQTT connection details and the settings intended for your device.

  • 03

    Check entities and values

    Next, check which values and control commands your device actually provides.

  • 04

    Test automation incrementally

    Start with a simple rule and observe behavior, limits, and failure scenarios.

ANY QUESTIONS?

MQTT & Home Assistant explained in brief

Does the novolto immersion heater work without internet?

Yes, local MQTT communication can run within your home network. Which additional functions require an internet connection depends on the respective scope of features.

Do I need the novolto app for that?

For your own local MQTT automations, you do not need the novolto app as a control center. You will continue to use your novolto account for novolto web app functions and cloud services.

Which data points are available?

The available MQTT scope may vary depending on the device and firmware. Therefore, please check which values and control commands your system currently supports during setup.

FURTHER GUIDES

More information about immersion heaters and surplus solar power

  • TERMS & TECHNOLOGY

    Immersion heater, heating cartridge, or immersion element?

    How the terms differ and which design is suitable for domestic hot water or buffer tanks.

    Terms explained 

  • ADVICE

    Is an immersion heater worth it?

    Profitability, self-consumption, and amortization honestly assessed.

    Regarding economic efficiency 

  • ADVICE

    Immersion heater or domestic hot water heat pump?

    A direct comparison of the two solutions in terms of efficiency, effort, and area of application.

    For comparison 

  • ADVICE

    Which electricity meter is compatible?

    Compare Tibber Pulse IR, poweropti, supported Shelly devices and MQTT-based measurement solutions.

    Regarding the electricity meter comparison 

  • OVERVIEW

    All guides

    Discover all articles on immersion heaters, surplus solar power, electricity readers, and smart control.

    View all guides 

  • COMPATIBILITY

    Check meter

    Check your electricity meter and chosen measurement setup before purchasing. Contact us if you need help confirming compatibility.

    Check compatibility 

NEXT STEP

This is how to proceed after local control

  • INSTALLATION

    Set up immersion heater

    Follow the instructions for assembly, network connection, and the initial setup steps.

    For installation 

  • IMMERSION HEATER

    Select appropriate solution

    Compare the available novolto immersion heater solutions for your storage system and your PV system.

    View immersion heater 

  • CONSULTING

    Clarify outstanding questions

    Are you still uncertain about integration or selection? Contact the novolto team directly.

    Contact