You would use spreadfooting when you cannot drill a hole deep enough for a standard post or post with laterals installation.
Q: The installer mounted the solar kit controller box 10’ in the air instead of down at a level that is accessible like the instructions say. Can I add a remote switch on the battery input to your solar kit so that they can turn it off at the bottom of the pole?
No if you switch the battery voltage ON while the inverter is already switched to ON it will not always start up. This is the reason that the power switch on the inverter is used to start and stop the system and the reason that the controller box must be mounted in an accessible location.
Yes they can, but it depends on the wall how well it will work. For example if there are steel studs or steel reinforcing it may not work that well. Nevco receivers for things like Locker Room Clocks are designed so that they can be mounted away...
Yes, the scoreboard has a detachable 6'7" IEC power cord that can be replaced with a longer one. The UL48 standard for signs limits the cord to 15' in length.
The specific type of anchor and structural capability of the building wall to support the weight of the display should be specified by the architect of the building or engineer of record for the school district.