Octopus Energy offers plunge pricing—also known as negative pricing—as part of its Agile Octopus tariff,

This is done to reflect real-time wholesale electricity market prices. Here’s why this happens and how it works:

⚡ Why Does Plunge Pricing Exist?

In the UK, electricity is traded on the wholesale market in half-hour slots. Sometimes, especially when there’s surplus renewable energy, prices drop below zero. This happens when:

• Solar and wind generation exceeds demand
• Power plants are still generating because it’s hard or costly to shut them down quickly

The grid will pay Octopus to use up this excess energy, Octopus passes these savings on to you by charging you in negative figures.

This guide shows you how to automate Home Assistant to react to negative electricity pricing from Octopus Energy. With this setup, when energy prices drop below zero, your system will automatically turn on selected devices. When prices go above zero, it will turn them off.

I use this to run some high-energy appliances in my shed, like a water heater, dehumidifier and lighting

Doing this when prices are negative, reduces my overall bill.

⚡ What You’ll Need

• Home Assistant set up with the Octopus Energy integration
• Entities or devices (lights, switches, plugs) you want to control
• Three YAML configurations:
  • An automation to monitor prices
  • A script to turn on devices
  • A script to turn off devices

🧠 How It Works

• The automation monitors the Octopus rate sensor:
  sensor.octopus_energy_electricity_********_********_current_rate, (Replace *** with your own octopus details)
• If the rate drops below £0.00, the turn-on script runs.
• If the rate rises above £0.00, the turn-off script is triggered.

⚙️ Automation YAML

Paste this into your automations.yaml file (or use the UI in YAML mode):

alias: Plunge pricing automation
triggers:
  - entity_id: sensor.octopus_energy_electricity_*********_**************_current_rate
    below: 0
    trigger: numeric_state
  - entity_id: sensor.octopus_energy_electricity_***********_************_current_rate
    above: 0
    trigger: numeric_state
conditions: []
actions:
  - choose:
      - conditions:
          - condition: numeric_state
            entity_id: sensor.octopus_energy_electricity_***********_************_current_rate
            below: 0
        sequence:
          - action: script.turn_on_devices
            data: {}
      - conditions:
          - condition: numeric_state
            entity_id: sensor.octopus_energy_electricity_***********_************_current_rate
            above: 0
        sequence:
          - action: script.turn_off_devices
            data: {}
mode: single

Replace sensor.octopus_energy_electricity_********_********_current_rate with your own Octopus Energy sensor

🔛 Turn On Devices Script

alias: Turn ON Devices
mode: single
sequence:
  - target:
      device_id:
        - ********************************
      entity_id: ********************************
    action: switch.turn_on
    data: {}
  - target:
      entity_id:
        - ********************************
    action: light.turn_on
    data: {}

Replace ********* with your own device_id or entity ID

🔴 Turn Off Devices Script

alias: Turn OFF Devices
mode: single
sequence:
  - target:
      device_id:
        - ********************************
      entity_id: ********************************
    action: switch.turn_off
    data: {}
  - target:
      entity_id:
        - ********************************
    action: light.turn_off
    data: {}

Replace ********* with your own device_id or entity ID

💡 Final Notes

• You need to adjust the sensor entity to match your Octopus account.
• Replace device/entity IDs with your actual devices (get them from Developer Tools).
• This automation works with Agile Octopus tariff only, using it with any other tariff will not reduce your bill.

If you’ve found this website helpful and you’re considering joining Octopus Energy, you can support this site by using the referral links below.

This helps cover hosting, cloud storage, and development costs and rewards you with credit on your new account too!

🏡 For Home Users

Sign up using this referral link and get £50 free Octopus Energy credit:
🔗 https://Telson.octopus.energy

🏢 For Business Users

Business customers using the same link will receive £100 in free credit after joining. 🔗 https://Telson.octopus.energy

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