Detection of a solar panel for a robotic work tool

A robotic work tool system comprising a robotic work tool configured to operate in an operational area comprising one or more solar panels each solar panel having a panel and one or more poles connected to the panel through a supporting structure, the operational area having a surface having at least one irregularity, and the robotic work tool comprising a controller, a memory configured to store supporting structure geometry data, an image sensor, wherein the controller is configured to:

• receive an image from the image sensor,
• detect a pole of the one or more poles in the image,
• determine a height of the detected pole,
• detect the supporting structure of the pole,
• determining a height of the detected supporting structure,
• determine a scale based on the determined height of the detected pole, wherein the pole is detected based on the stored supporting structure geometry data based on the determined scale, adjust at least one of navigation of the robotic work tool or operation of a work tool carried by the robotic work tool, and
• wherein the controller is further configured to determine the scale based on a ratio between determined heights to known heights of the detected pole and the supporting structure.