The rain rain sensor on the solar powered fresh air skylight seen here is the small gray box on the right side of the panel attached to the bottom of the skylight.
Velux skylight rain sensor problems.
Velux has a remedial option if a customer insists the skylight closes whenever it rains.
The skylight is then flashed sealed to become part of the roof.
This particular type of rain sensor replaces an electric one because it would require too much continuous current to draw on the batteries in a solar charged system.
The rain sensors work when they get wet.
A wire extension can be ordered directly from velux to accommodate moving the sensor panel.
This could be due to the sensor being shielded by the window sash on a steeper pitch.
A deck mount skylight unlike a curb mount skylight is simply attached directly to the roof deck.
Based on the above we should expect to get paid for the installation that delivers what it promises.