Hello all-
I am a new member to the forum and was directed here by a friend who suggested this community may be able to help with sorting out some diagnostics and setup issues I am having with my DUAL Victron Multiplus 12/3000/50 120v installation.
My system was installed a year ago by a licensed electrician familiar with solar and larger off grid systems, but who had never worked with RV's or Victron equipment & the mix of (relatively) small-scale 12V DC and 120V AC. As such, the initial configuration and details of Parallel vs Split-Phase wiring and setup were never fully understood by or explained to me, and within a short time issues started to appear. After learning some basics myself, it appears that my system was wired to be used as a split-phase setup (see PDF single line drawing attached as provided to me by the installer), but the two Multiplus inverters were never connected via an RJ45/Ethernet communication cable, and so have basically been operating as two separate standalone units, each serving one side of my RV's AC breaker panel. As I have learned, this will lead to some issues since the Neutral wire is shared between the units, but they have no way of knowing what the other unit is doing.
The two problems I have been experiencing are:
1) The biggest issue is this: When connected to a 240v 50a shore power receptacle, if I set the input AC current on either inverter to MORE than 20a, I start running into major issues when any significant load is applied (Air Con, Electric FP, etc) - the inverter will give me overload errors, will bounce between Pass-Thru, Assisting, Inverting modes, and will sometimes actually show a NEGATIVE AC input, as though it is trying to back-feed the grid, though have never actually put a clamp meter to this to verify if it is actually happening. If I keep the shore input to 20a or less on each inverter, they operate flawlessly regardless of shore power connection type (or when strictly off-grid/inverting), which is basically what I have been doing for the last year as we live & travel full-time in our RV.
2) Secondary, and less important issue is that I pop the GFI on any 120v 15a or 20a GFI-protected receptacle within 5-10 seconds of connecting to it, if that happens to be my shore power connection.
After doing much reading on this forum and elsewhere, I think what I need to do is simply disconnect from shore power, connect my Multiplus' together (via RJ45/Ethernet), and connect one of them to my laptop via RJ45/Ethernet cable and program them in Split-Phase through the VictronConnect app (I have a Victron USB MK3 Dongle). But before I do this, I wanted to reach out to all of you to see if there is anything else in my setup that is of concern, or that would prevent me from doing this. Again, please see the attached PDF single line drawing that includes my hardware details.
If I go this route (Program to Split-Phase), it is my understanding that when on a 240v 50a shore connection, the Multiplus' will each pass through 50a to one side of my AC breaker panel, and that everything will work as expected with ample power available. When connected to a 120v 30a (or 20a or 15a) shore connection, one inverter will pass through that amount (or use to charge batteries), plus the "Assist" wattage will also be available from that inverter. The second inverter will reject the incoming shore power (since it is the same phase) and will operate in Inverter mode only, up to its maximum inverter wattage. Do I understand this correctly?
The other option I have considered is to go the parallel route, but it is my understanding that some re-wiring would need to be done to facilitate this, and that I would always be limited to the maximum amperage of one leg of any shore connection (ie 50a total on a 240v 50a shore connection). Is this correct?
Greatly appreciate any advice or feedback you can offer - thank you!
Josh
Details on hardware & wiring:
AC Wiring To/From Shore/Inverters/AC Panel: 6/2 & 6/3
DC Wiring: 4/0 To/From/Between Batteries, 4/0 To Multiplus' from Lynx Distributor
6 - Battle Born 12V 100Ah
2 - Multiplus 12/3000/120-50 120v VE Bus
1 - Victron Lynx Distributor
1 - Victron BMV-712 Battery Monitor
2 - Microair EasyStart 364 (One on each Air Conditioner)
2 - VE.Bus Smart dongle
1 - Victron SmartSolar MPPT 150/85
1 - Battery Guard AutoSelect
6 - Canadian Solar 305w solar panels
