Appliance Energy Cost

Adds a cost sensor to each of your existing appliance energy sensors — money counted the way the meter counts energy, every reading priced at the price in force when the energy was actually used.

It does:

• Give every appliance you configure one cost sensor that grows as the appliance spends money — live from the moment you add it.
• Price energy at the moment it was used — a later price never re-prices earlier consumption.
• Reconstruct past cost from history Home Assistant already stores — preview first, nothing is written without an explicit confirm.
• Run entirely locally — no cloud, no accounts, nothing leaves your Home Assistant.

It does not:

• Calculate electricity prices. You point it at one price sensor whose value is the full price you pay; the integration adds nothing to it.
• Estimate consumption. Only energy an existing sensor has already measured is costed.

Install

You need three things:

• A cumulative energy sensor for each appliance you want to cost — one that counts total energy upwards, in Wh, kWh or MWh.
• An all-inclusive price sensor in your currency per kWh or MWh.
• Recorder enabled — it is on by default in Home Assistant.

Then:

1. In HACS, add https://github.com/jonikanerva/appliance_energy_cost as a custom repository of type Integration, download Appliance Energy Cost, and restart Home Assistant.
2. Go to Settings → Devices & services → Add integration and search for Appliance Energy Cost.
3. The wizard first asks for the price sensor and currency — pick a price sensor that already includes transfer, taxes and margins; the integration adds nothing on top. (Backfilling history additionally needs a price sensor that records statistics — state_class: measurement; the wizard warns if it does not.)
4. Name your first appliance and pick its energy sensor. Add more appliances at any time with Add appliance on the integration's page.

Use

Every appliance you added got one sensor. When the energy sensor belongs to a device, the cost sensor sits on that device's page and is named Cost; otherwise it is a standalone sensor named <Name> cost. All of them are listed on the integration's page under Settings → Devices & services.

The sensor's value is the cumulative money spent since it started counting, in your configured currency. It survives restarts and keeps growing — a meter, for money.

To chart costs:

• Daily or monthly bars: add a Statistics graph card for the cost sensor, set the stat type to Change, and the period to Day (a bar per day) or Month (a bar per month).
• Single numbers: add a Statistic card for the cost sensor, choose Change, and pick a calendar period — today for cost so far today, month for month-to-date, or one period back for yesterday or last month.
• The figures refresh about every 5 minutes, and days and months follow your Home Assistant timezone.
• The Energy dashboard is not applicable: it accepts energy sensors, not money sensors.

Backfill

A cost sensor starts counting when you add it. If your energy and price sensors are older, the backfill reconstructs what the appliance cost before that — the past shows up in the same charts. Nothing is written without a preview and an explicit confirm.

1. Open Developer tools → Actions and pick Appliance Energy Cost: Preview energy cost backfill. Choose the integration entry and leave Start and End empty — the defaults cover everything from the first hour your price sensor recorded up to now. Run it.
2. Read the summary it returns: ok should be true and each appliance's point count should look like the hours its history covers. Anything unexpected — check the technical reference before importing.
3. Pick Appliance Energy Cost: Import energy cost backfill with the same values, keep Overwrite existing and Calibrate cost sensors ticked (the form pre-ticks them), tick Confirm, and run it. The response confirms the rows written and shows each live sensor's new value — the history lands in the charts and the sensors continue seamlessly from it.
4. If the response shows a calibration_skipped reason for an appliance, the history is still imported; the reason names the remedy (usually: run the same import again). Details in the technical reference.

Remove

• Remove a single appliance from the integration's page — its cost sensor is removed with it.
• Remove the whole integration from Settings → Devices & services, then uninstall the repository in HACS and restart Home Assistant.

Cost history already recorded or imported stays in your database — removing the integration never deletes the old numbers.

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Detailed technical reference — configuration options, action fields and responses, cutover, known limitations, troubleshooting: docs/reference.md

Licensed under the MIT License.