An illumination system has a controller stack that includes multiple power conversion and LED driver assemblies and a pole-mounted backplane that provides power and communication connections. The pole-mounted backplane further acts as a heat-sink and efficiently transmits excess heat to the pole on which the controller stack is mounted. The controller stack and its components include weathertight housings and connectors for outdoor applications, and it includes a master, which monitors the system operation and can switch to a backup LED driver based upon its monitoring of system operation.