Morningstar MeterHub (Hub-1) Works with MODBUS

I recently added another PV panel and SunSaver MPPT charge controller to my off-grid system and started having trouble communicating with my SureSine inverter when the system voltage went over about 13.3 volts. Each of these Morningstar products has a RJ-11 (phone jack) port that can be used for a remote meter or, by changing a DIP switch, used for MODBUS communication. For the past few years, I've had just one SunSaver MPPT and one SureSine. I connected these to a Morningstar Meterbus to Serial Converter (MSC) using a telephone splitter. The telephone splitter just ties all the same lines together. I had no problems with this, although it is not an ideal setup from an electrical perspective (no isolation between devices). I once had the SureSine inverter disconnected from the batteries and the LEDs stayed on because it was getting power over the Meterbus port (not good). When I added a second SunSaver MPPT and another telephone splitter, I think the Meterbus voltage must have been getting doubled and the SureSine inverter couldn't comunicate very well.

I contacted Morningstar about whether the MeterHub would work for my application of MODBUS communication between these three devices and the MSC. The documentation doesn't list the SureSine-300, the MSC, or MODBUS communication. The MeterHub is mainly designed to tie multiple Morningstar devices to their remote meters and relay box. Morningstar responded that the MeterHub would work for my application, so I ordered one. I installed it last night. It seems to work great and now all the devices are properly isolated from each other. Note that the MSC is not a powered device, so it needs to be attached to port A and one of the powered devices (SunSaver MPPT or SureSine300) needs to be attached to port B. The rest of the powered devices are attached to ports 1 through 4.

Photo of the setup:
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