The GPS module is designed to work with the Bell box controller.
It allows the bell box to get time sync, and set the time for the Solar System. Normally time can be set by Internet access (NTP), but in the absence of Internet access the system continues. In the event of a power cut this could mean a loss of time and Internet access. The GPS module simply ensures that as long as the Solar System mesh is working, the system as a whole has accurate time, and so can enforce time constrained access controls.