In a standard pergola configuration, the control box is typically installed within the side beams, with the power cord routed through one of the two rear posts (columns). However, in a wall-mounted configuration, there are no rear posts/columns available to run the cable through.
If you would like the power to run through the back in this setup, you can install the cable as shown in the image below.
Please ensure the grounding wire is securely connected to the wall or mounting surface the pergola is anchored to. This is essential for safety and to ensure a compliant installation.