Home Assistant app

The app provides an ingress UI for configuring, validating, running, and reviewing Powercalc measurements. It uses Home Assistant entities to control devices and can read power from either a Home Assistant sensor or a Shelly plug. Home Assistant supplies authentication and Core API access, so you do not create or paste a long-lived access token.

Availability and installation

1. In Home Assistant, open Settings > Apps > App store.
2. Open the app-store repository menu and add https://github.com/bramstroker/powercalc-measure-app.
3. Find Powercalc Measure, select Install, and wait for the pre-built image to download.
4. Start the app and select Open Web UI. Optionally enable Show in sidebar.

No port, host networking, Home Assistant configuration mapping, or API credentials are required. App installation is not available on non-Supervisor installation types.

Current scope

The app supports these power-meter types:

• a Home Assistant power sensor reporting W, with automatic association of an optional voltage sensor reporting V;
• a directly polled Shelly plug, selected through network discovery or entered by IP address;
• a synthetic test meter for development and UI testing only.

Direct Hue, Tuya, Kasa, Tasmota and myStrom controllers or meters, OCR, and manual power entry remain CLI-only.

Measurement device setup

Configure the measurement device once from the app settings before creating a session. Select the power-meter type, choose or discover the sensor or Shelly plug, and enter a recognizable measurement-device name for generated profile metadata.

Use Test connection to sample the configured meter before starting a long run. For Home Assistant sensors, the app checks:

• whether readings can be retrieved;
• whether the sensor reports at least 0.1 W resolution;
• how often the source reports a new reading;
• whether the update interval is suitable for reliable measurements.

An update interval of two seconds or faster is recommended. Intervals above five seconds, no observed updates, or insufficient precision are reported as poor measurement quality. Directly polled Shelly meters are checked for connectivity and a valid reading; Home Assistant reporting cadence does not apply to them.

Measurement safety

Keep people, automations, adaptive-lighting systems, and other controllers from changing the device during a run. Verify that the chosen power meter measures only the target load, and keep Home Assistant, the device, and the meter powered and reachable until completion.

Using a resistive dummy load

A resistive dummy load can raise a low device load into a range that the power meter measures accurately. The app supports this for light, speaker, fan, charging, average, and recorder measurements made with a real power meter.

Dummy-load correction requires voltage readings. The selected Home Assistant power sensor must have an associated voltage sensor reporting V, or the Shelly meter must provide voltage. The synthetic test meter cannot be used for dummy-load measurements.

Before the first measurement, the app calibrates the resistance of the warmed-up dummy load:

1. Connect only the dummy load to the power meter and let it warm up.
2. Confirm that calibration can start. The app measures at least 20 periods of 30 seconds, so calibration takes at least 10 minutes.
3. If the resistance is still rising or falling, let the app continue until the reading is stable.
4. Connect the target device in parallel without disconnecting the dummy load, then confirm that measurement can start.

The app stores a successful calibration for that power meter. A later session can reuse it after you explicitly confirm that the same warmed-up load is connected, or you can choose Recalibrate. Recalibrate after changing the dummy load, power meter, or wiring, or whenever stability is uncertain.

During the actual run, live and saved power readings show the target device consumption after subtracting the calculated dummy-load contribution. A calibration interrupted before its resistance becomes stable is not saved.

Running a measurement

1. Configure and test the measurement device in Settings.
2. Select a measurement type and the Home Assistant entity when that measurement controls a device.
3. Enter the profile details and measurement-specific options. Light measurements also let you choose the modes advertised by the selected entity. Enable a resistive dummy load only when the device load would otherwise be too low for the meter.
4. Review preflight estimates, warnings, meter diagnostics, and advanced timing settings.
5. Start the session. Complete the dummy-load calibration or reuse confirmation when enabled. Average, recorder, speaker, and charging measurements also pause for an explicit confirmation when the physical device must be prepared or the actual sampling period is about to begin.
6. Follow live progress, current operating values, recent power samples, and session logs. You can close or reload the browser; the app owns the job and restores its persisted status when you return.
7. Review plots and download generated CSV, model, or recording files from the result view.

Only one measurement runs at a time.

Cancellation and resume

Cancellation is cooperative. A device request or configured wait already in progress may finish before the app stops changing the device. The app keeps complete output rows and does not mark partial output as completed.

Light LUT measurements can resume compatible partial output. Resume with the same light, meter, modes, and measurement settings. Other measurement types currently start a new session after interruption. If the UI does not offer resume, start over rather than manually editing session files.

Storage and backups

Requests, session state, events, and output are stored in the app's private /data directory. Home Assistant includes this directory in app backups. The app does not mount or write to the Home Assistant configuration directory.

The result view provides:

• raw measurement and generated model files;
• interactive plots for supported output;
• high-resolution plot image downloads;
• a diagnostics download containing the session snapshot, request, events, logs, and file inventory for issue reports.

Entity IDs remain present in diagnostics because they are useful when troubleshooting entity selection and state updates. Download files through the authenticated ingress result view before removing the app or deleting its data.

Troubleshooting

A device or sensor is not listed

Confirm that the entity is available in Home Assistant and belongs to the required domain for the selected measurement. Power sensors must report W; optional voltage sensors must report V. Correct the source integration or unit, then reload the app.

Power-meter validation warns about quality

Watch the sensor in Home Assistant Developer Tools while changing the load. The source should expose at least one decimal place and publish a new reading every two seconds or faster where possible. Increase the source integration's update rate or use a faster meter before starting the full measurement.

Dummy-load calibration is unavailable or unstable

Confirm that the configured meter provides voltage readings. Home Assistant voltage sensors must report V; a Shelly must expose voltage through its meter API. The synthetic test meter does not support calibration.

If resistance does not stabilize, allow the load to warm up longer and ensure no other load behind the meter is changing. Recalibrate after correcting the setup. Do not continue with a stored calibration when the physical load, meter, or wiring has changed.

Shelly discovery does not find the plug

Confirm that Home Assistant and the Shelly are on a network where mDNS discovery is available. IPv6-only and non-private addresses are not accepted. You can enter the device's private IPv4 address manually when discovery is unavailable.

Ingress disconnected

Reload the app. Browser and ingress connections do not control the worker, and the UI restores the authoritative session snapshot. Review app logs if reconnecting continues to fail.

An interrupted run cannot resume

Resume is rejected when output is incomplete or settings that determine the measurement sequence changed. Preserve the existing files for diagnosis, then start a new session with overwrite when appropriate.

Storage errors

Check free disk space and the app log, then restart the app. Do not remove files from app data while a measurement is active. Restore the app data from a Home Assistant backup if needed.

Reporting a problem

Enable debug logging in the app configuration and restart the app before reproducing the issue. After the session, download its diagnostics from the result view and attach that file to the issue together with the app log. Disable debug logging again after collecting the information.