Fig. 5 – ProStar MPPT system with Ethernet MeterBus Converter (EMC-1): The EMC-1 power has a
common negative with the RJ-11 port. Therefore, using a single-pole battery breaker as shown on the
left will not break the negative connection to the controller and it could cause damage to the
communications circuits. A double-pole breaker which disconnects both the positive and negative
conductors as shown in the right can be used in order to disconnect the ProStar MPPT controller without
harm to the serial communications. Also note that the fuse for the power circuit to the EMC-1 should be
installed on positive wire.
Fig. 6 – TriStar MPPT and Relay Driver system with an RJ-11 MeterBus connection: The MeterBus
RJ-11 creates a common negative connection between the controller and relay driver. The single-pole
battery breakers as shown on the left will not break the negative connection to the controller and it could
cause damage to the communications circuits. A double-pole breaker which disconnects both the
positive and negative conductors as shown in the right can be used in order to disconnect the TriStar
MPPT controller without harm to the MeterBus communications.
