Overview
On the Shelly Wave Motion sensor, the illuminance sensor is a secondary sensor. This means that the main function of the device is motion detection. The light level measurement is an additional function and is not measured continuously. Because the device is battery-powered, it does not stay awake all the time. It wakes up only when needed to save battery.
When illuminance is measured
The illuminance value is measured when:
Motion is detected
The device wakes up
When one of these events happens, the device can measure the light level and report the value to the gateway.
Manual illuminance measurement
There is no setting that allows the user to manually start an illuminance measurement.
This means that the illuminance value cannot be requested at will from:
The gateway
An automation
A manual command
A dashboard button
The device will update the illuminance value only when it performs a measurement during motion detection or wake-up.
Why it works this way
The device is battery-powered. To save battery, the sensor does not measure and report illuminance all the time. Continuous or manual measurements would require the device to wake up more often, which would increase battery usage. For this reason, illuminance is not the primary function of the device.
Workaround: reduce the wake-up interval
As a workaround, you can reduce the wake-up interval. A shorter wake-up interval makes the device wake up more often. When the device wakes up, it can measure and report the illuminance value more often.
Important battery note
Reducing the wake-up interval will increase battery use. This can reduce battery life. Use a shorter wake-up interval only if more frequent illuminance updates are needed. If long battery life is more important, keep the wake-up interval at a higher value.
Home Assistant with Z-Wave JS UI
In Home Assistant with Z-Wave JS UI, the wake-up interval can be changed under:
Device → Values → Wake Up
The value is normally set in seconds.
After changing the wake-up interval, wake up the battery device manually so it can receive the new setting.
Summary
The illuminance sensor is a secondary function of the device. It measures light level when motion is detected or when the device wakes up. There is no option to start illuminance measurement manually or through an automation. To receive illuminance updates more often, reduce the wake-up interval, but note that this will increase battery consumption and reduce battery life.