Smart Heating with Mill and Home Assistant: Control Your Panel Heaters Based on Electricity Prices

Electric heating is common across Europe, especially in countries where panel heaters are widely used for both homes and cabins. While modern smart heaters already provide app-based scheduling, integrating them with Home Assistant opens up a completely different level of automation.

If you already use Mill smart panel heaters, connecting them to Home Assistant allows you to combine temperature control with real-time electricity pricing, occupancy detection, presence-based automations, and advanced scheduling.

In this guide, we will look at how to integrate Mill with Home Assistant and create a practical automation that adjusts room temperatures automatically based on electricity prices measured in NOK per kWh.

Why Integrate Mill with Home Assistant?

The official Mill app is easy to use and works well for basic scheduling. You can create heating programs, adjust target temperatures, and monitor your heaters remotely.

However, Home Assistant adds several advantages:

• Centralised control of all smart devices
• Integration with electricity price sensors such as Nordpool
• Presence-based heating automation
• Better energy optimisation
• Advanced scheduling logic
• Full automation using YAML

This means your heaters can react dynamically instead of simply following static schedules.

For example:

• Raise temperatures when electricity prices are low
• Reduce heating during expensive peak hours
• Automatically switch to eco mode when nobody is home
• Preheat your home before arriving

This helps reduce energy consumption while maintaining comfort.

What You Need

To follow this setup, you will need:

1. Mill Smart Heater

Any Mill heater supported by the Mill cloud platform should work.

Examples include:

• Mill WiFi panel heaters
• Mill glass panel heaters
• Mill oil-filled radiators with WiFi

The heater must already be configured in the Mill app.

2. Home Assistant

You need a working Home Assistant installation.

If you are new to Home Assistant, it can run on:

• Raspberry Pi
• Virtual machine
• Dedicated mini PC
• Home Assistant Yellow

3. Mill Integration

Home Assistant includes native support for Mill through the built-in integration.

To add it:

1. Go to Settings
2. Select Devices & Services
3. Click Add Integration
4. Search for Mill
5. Enter your Mill account credentials

Once connected, Home Assistant will automatically discover your heaters.

4. Electricity Price Sensor

To optimise heating costs, you need electricity pricing data.

A popular option in Europe is the Nordpool integration, which provides hourly electricity prices in kWh.

Typical entities might look like:

sensor.nordpool_kwh_no3_nok_3_10_025

This gives current electricity pricing in NOK per kWh.

What Components Does the Mill Integration Create?

After setup, each heater appears as a climate entity.

Example:

climate.living_room_heater

These entities usually provide:

Current Temperature

The measured room temperature in °C.

Target Temperature

The setpoint your heater is trying to maintain.

HVAC Modes

Common modes include:

• Heat
• Off

Preset Modes

Depending on the heater model:

• Comfort
• Eco
• Away

These entities can be controlled directly through automations.

A Practical Use Case: Heating Based on Electricity Prices

Let us build a useful automation.

Goal

We want the heater to:

• Maintain 22°C when electricity prices are low
• Reduce to 18°C when prices are high
• Check prices every hour
• Automatically optimise heating costs

This approach works especially well during winter when electricity prices fluctuate significantly throughout the day.

How the Automation Works

The automation uses:

• A Nordpool electricity price sensor
• A Mill climate entity
• A threshold value in NOK per kWh

Logic:

• If electricity price is below 1.20 NOK/kWh, heat normally
• If electricity price is above 1.20 NOK/kWh, reduce temperature

This creates a balance between comfort and savings.

YAML Automation Example

Add this to your automations.yaml file:

alias: Mill Heating Based on Electricity Price
description: Adjust heater temperature depending on hourly electricity prices

trigger:
  - platform: time_pattern
    minutes: "0"

condition: []

action:
  - choose:
      - conditions:
          - condition: numeric_state
            entity_id: sensor.nordpool_kwh_no3_nok_3_10_025
            below: 1.20
        sequence:
          - service: climate.set_temperature
            target:
              entity_id: climate.living_room_heater
            data:
              temperature: 22

      - conditions:
          - condition: numeric_state
            entity_id: sensor.nordpool_kwh_no3_nok_3_10_025
            above: 1.20
        sequence:
          - service: climate.set_temperature
            target:
              entity_id: climate.living_room_heater
            data:
              temperature: 18

mode: single

Understanding the Automation

Let us break it down.

Trigger

platform: time_pattern
minutes: "0"

This runs the automation at the start of every hour.

This aligns perfectly with hourly electricity pricing updates.

Condition Check

The automation evaluates the current price in NOK per kWh.

Temperature Adjustment

If prices are low:

• Set heater to 22°C

If prices are high:

• Reduce to 18°C

The exact thresholds can be adjusted depending on your electricity contract.

Taking It Further

This basic automation can easily be extended.

Add Presence Detection

Only heat fully when someone is home.

Example:

condition:
  - condition: state
    entity_id: person.home
    state: home

Night-Time Setback

Reduce heating automatically during sleeping hours.

For example:

• Day: 21–22°C
• Night: 17–18°C

Cabin Preheating

If you have Mill heaters in a cabin, combine them with calendar events.

Home Assistant can automatically raise temperatures several hours before arrival.

Weather-Based Heating

Combine outdoor temperature sensors.

For example:

• If outside temperature drops below -10°C, increase heating slightly
• If outside rises above 10°C, reduce heating

Real Energy Savings

Electric heating can represent a significant part of household energy use.

A single 1000 W panel heater running continuously for 10 hours uses:

10 kWh

If electricity costs:

1.50 NOK/kWh

That equals:

15 NOK

Reducing runtime during expensive periods can make a noticeable difference over an entire heating season.

When multiple heaters are controlled intelligently, savings add up quickly.

Final Thoughts

The Mill integration for Home Assistant is one of those setups that combines convenience with real practical value.

You keep the simplicity of Mill hardware while gaining the flexibility of Home Assistant automation.

By linking your heaters to electricity pricing data, you can:

• Improve comfort
• Reduce energy costs
• Automate heating intelligently
• Make better use of hourly electricity pricing

If you already own Mill heaters, integrating them with Home Assistant is absolutely worth doing.

It only takes a few minutes to set up, and the automation possibilities are extensive.

Once connected, your heating becomes a fully dynamic part of your smart home.