It would be nice if you would only have to attach a power line at one point of the wall to get power from it. Especially before you get substations, having to cover every single wall tile is quite annoying (more so if you still use projectile turrets which don't even need any power).
The easiest solution would probably be to add an integrated 1x1 power pole with 1 tile connection distance to the walls, though I don't know how much UPS impact 1000s of poles would have on your game. Alternatively, you could add a connector entity which collected the energy of all connected solar walls (lua flood fill search for connected walls; all found walls are added to coordinate-indexed array(O(#walls) if not already in array, O(1) otherwise); onBuildingPlaced Event with new solar wall: check if adjacent to established solar wall, if so add new entry to array (O(1)); connector power output is set by lua script depending on the number of connected walls).
