To align panels to the edge while designing a solar system:

1. Select the roof area where the panels have been placed.
   
2. Again click on / select the specific side or edge where you want the panels to be aligned.
3. When you select the desired edge , you will see a thin white line and on the right side there will be an option to  "Align panels to this edge"
   
4. Click on "Align panels to this edge".
   
5. You can then adjust the tilt, orientation, and spacing as needed to maximise efficiency while maintaining alignment with the edge.