What Home Assistant is (and who it's for)

Home Assistant is free, open-source home automation software. You run it on a small device in your home, typically a Raspberry Pi or a dedicated mini PC. It connects to smart bulbs, thermostats, EV chargers, smart plugs, boilers, and thousands of other devices. You control everything from a single dashboard and build automations using a visual editor.

It is not just for developers. The community is vast and the documentation is excellent. The most common Home Assistant setup involves no programming at all. You install integrations from a built-in store, configure them through a web interface, and write automations using simple "when this, do that" logic in plain language.

For Octopus Agile users specifically, Home Assistant is the most powerful free tool available. Once you connect the Octopus Energy integration, your entire smart home can respond to live electricity prices. When power costs 4p per kWh, your washing machine starts. When it costs 38p, your dishwasher waits. You set the rules once and the system handles the rest.

The price difference matters enormously. At July 2026 Ofgem cap rates, peak electricity hits 38p per kWh. Overnight Agile windows regularly fall to 3p to 5p. That is a ratio of nearly 10-to-1. A single washing machine cycle at 40 degrees uses around 2 kWh. Run it at peak and it costs 76p. Run it at 4p and it costs 8p. Multiply that across every flexible load in your home and the savings compound fast.

Installing the Octopus Energy integration

Before installing anything, you need a running Home Assistant instance. The recommended route is Home Assistant OS on a Raspberry Pi 4 or the official Home Assistant Green hardware. Both cost around £70 to £100 and last for years. You can also run Home Assistant in a virtual machine or as a Docker container if you already have a home server.

Once Home Assistant is running:

  1. Go to Settings, then Add-ons, then the Add-on Store and install HACS (the Home Assistant Community Store). This takes about 5 minutes.
  2. Once HACS is installed, search for "Octopus Energy" in the HACS integrations section. It is maintained by BottlecapDave and has over 4,000 stars on GitHub.
  3. Install the integration and restart Home Assistant.
  4. Go to Settings, Devices and Services, then Add Integration. Search for "Octopus Energy".
  5. Enter your Octopus API key (found in your Octopus account under API access) and your account number.

After a minute or two, Home Assistant will populate dozens of new entities: your current Agile unit rate, the rates for every half-hour slot today and tomorrow, your consumption data, your account balance, and more. The integration pulls live data directly from the Octopus API.

You now have a sensor called something like sensor.octopus_energy_electricity_current_rate. Every automation you build will reference this sensor.

Your first automation: running an appliance below a price threshold

The simplest and most useful automation turns on a smart plug when the Agile price drops below a threshold you choose. Here is how to build it without writing any code.

First, plug a smart plug into your washing machine or dishwasher. Any Zigbee, Z-Wave, or Wi-Fi plug that works with Home Assistant is fine. TP-Link Kasa, IKEA Tradfri, and Sonoff S26 are all popular choices under £15.

Then in Home Assistant:

  1. Go to Settings, then Automations and Scenes, then Create Automation.
  2. Under Triggers, choose "Numeric state".
  3. Select the entity sensor.octopus_energy_electricity_current_rate.
  4. Set the trigger to fire when the value goes below 0.05 (that is 5p per kWh).
  5. Under Actions, choose "Call service" then "switch.turn_on" and select your smart plug.
  6. Save the automation.

From this point on, whenever the Agile rate drops below 5p, the plug turns on and the appliance connected to it starts running. You can add a second automation that turns the plug off when the price rises above your threshold again.

This single automation, applied to a washing machine run every other day, saves around £60 to £90 per year compared to running it at peak. Scale that logic to your dishwasher, tumble dryer, and immersion heater and you approach the Octopus-reported average saving of £440 per year for active Agile users.

Notifications: getting alerted to cheap windows and plunge pricing

Plunge pricing is the most dramatic feature of Octopus Agile. Prices go negative, meaning Octopus pays you to use electricity. The floor is -20p per kWh, and genuine plunge events happen 5 to 10 times per month. A single 2-hour plunge event on your immersion heater earns you 40p and heats your water for free.

Home Assistant can notify you on your phone the moment a plunge event starts. To set this up:

  1. Install the Home Assistant app on your iPhone or Android device. This creates a notification service tied to your phone.
  2. Create a new automation with a trigger on sensor.octopus_energy_electricity_current_rate going below 0 (zero pence).
  3. Set the action to call notify.mobile_app_your_phone with a message like "Agile price is negative. Free electricity now."

You can also build notifications for your personal cheap threshold, whether that is 5p, 8p, or 10p. Some users set up an automation that sends a summary each evening when tomorrow's prices are published (usually around 4pm), listing the cheapest 3-hour window overnight.

The AgileAlert live price dashboard shows you the same information in a visual chart without any setup required. For casual monitoring, start there. For automated action, Home Assistant notifications are the natural next step.

Dashboard: displaying live Agile prices at home

One of Home Assistant's strongest features is its Lovelace dashboard editor. You can build a full-screen energy overview for a wall-mounted tablet showing live prices, your current consumption, when the next cheap window starts, and how much you have spent today.

A basic energy dashboard takes about 20 minutes to build. The components to add:

The HACS frontend store also has a card called Octopus Energy Rates Card, which renders a colour-coded half-hourly price chart identical in style to the charts on the AgileAlert website. Green bars are cheap slots, red bars are expensive ones. A glance tells you everything you need to know.

Advanced moves: battery charge/discharge automation

Once you are comfortable with basic automations, the most powerful use of Home Assistant with Agile is controlling a home battery. Systems like the Givenergy, Solis, and Tesla Powerwall all have Home Assistant integrations. The logic is straightforward: charge the battery when prices are below 5p, discharge it during the 4pm to 7pm peak period when rates hit 35p to 40p.

A 10kWh battery charged at 4p costs 40p to fill. Discharging that same 10kWh at 38p saves you £3.80 in grid consumption. Do this daily and the saving is over £1,300 per year from battery arbitrage alone. Battery costs have fallen significantly and typical payback periods in 2026 run 5 to 7 years for a well-automated system.

Home Assistant handles this through the built-in Scheduler card or through the Octopus Energy integration's built-in "Saving Sessions" entity, which alerts you to Demand Flexibility Service events and can automatically shift your battery discharge to match.

Before you reach that stage, check what today's prices look like on the live AgileAlert dashboard. Understanding the daily price pattern is the foundation for building automations that respond intelligently to it.

Is Home Assistant worth the setup time?

The honest answer: yes, for most Agile users who run flexible loads regularly.

The initial setup takes 45 minutes to 2 hours depending on your existing smart home setup. After that, automations run silently and save money every day without you doing anything. Users who automate their washing machine, dishwasher, tumble dryer, and immersion heater typically save £300 to £500 per year purely from timing shifts.

The platform is not perfect. Updates occasionally break integrations. Some hardware requires more configuration than others. The community forums are active and helpful, but you will spend occasional evenings troubleshooting.

If you want the benefits of Agile automation without any setup, the combination of manual price checking via AgileAlert, delay-start buttons on appliances, and a single smart plug covers the majority of available savings at zero cost. Home Assistant is the next level for those who want their home to act without prompting.

Frequently asked questions

Do I need to be technical to use Home Assistant with Agile?
No. The Octopus Energy integration installs through a store like an app. Basic automations use a visual editor with dropdown menus, not code. Most beginners have their first price-responsive automation running within an hour. The community at reddit.com/r/homeassistant and the official forums are extremely helpful if you get stuck.
What hardware do I need to run Home Assistant?
The most popular options are a Raspberry Pi 4 (2GB or 4GB RAM, costs around £45 plus SD card), the official Home Assistant Green (around £95, plug-and-play), or the Home Assistant Yellow (around £130, includes Zigbee radio). You can also run it as a virtual machine on a Windows or Mac computer you already own. Any of these works perfectly with the Octopus Energy integration.
Can Home Assistant control my EV charger?
Yes, for many popular models. Ohme, Zappi, Wallbox, and Hypervolt chargers all have Home Assistant integrations. The most capable is the Ohme integration, which lets you set target SOC, charge windows, and smart charge schedules based on live Agile prices. Zappi has a dedicated HACS integration as well. Check the Home Assistant integration directory for your specific charger model.