“Wallwalker” is a robot that helps to maintain solar units. The robot can work on flat surfaces and inclines up to 90°, such as solar modules. To do so it climbs over the frames and the connecting elements so that the solar area does not need any additional installation. As the robot must not damage the modules, every gram saved in weight counts here. The robot's “feet” are therefore joined to the base by the flat and particularly light igus® drylin® N low profile linear guides. The cleaning brush is fitted on a hollow shaft with igubal® flange bearings.