Updated: Dec 8, 2020
VELUX windows with remote control operation always include a rain sensor but depending on whether these are Electric or Solar powered the rain sensor works in different ways.
Electric Rain Sensor
The rain sensor on Electric VELUX Integra models senses moisture, when the sensor becomes moist enough it completes a
circuit telling the window to close.
Solar Rain Sensor
Built into the solar panel unit this rain sensor cannot work in a similar way as the electric model as this would constantly drain the battery. Instead the solar models use a Piezoelectric rain sensor, which basically reacts to sound. The device uses the piezoelectric effect to measure changes in temperature, pressure and sound by converting them to an electrical charge. In this case, the sound of rain hitting the sensor triggers a subtle change in shape (a ‘press’ or ‘squeeze’, as the Greek prefix piezo implies) that generates a voltage to alert the skylight of rain and close it.