I have a glass patio roof with a 15° incline. The robot only moves around in a circle or semi-circle on the spot. So @Stardustone's statement is not correct. At first I thought Galaxus had sent me a device that was not perfect. I then tested the device on a window and it worked perfectly there.
No, the robot can only clean glass surfaces with a tilt angle of 60 - 120 degrees. Terrace roofs do not normally fall under this. Other statements about this are incorrect.