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I have read the Victron document concerning ac-coupling and Factor 1.
I was wondering if the 1:1 ratio still applied in the situation below (see diagram) if the system is off grid and the batteries are connected to the Sofar. Thanks.
(It would be impractical to rewire the system to just use the Victron at the moment)
The 1:1 ratio is for AC PV that has no battery on it. I think in your case you may be fine.
Are you planning on using ESS there? What would be the purpose of the Victron in this system? And FYI the Victron does have a minimum battery requirement for safe operation.
l was just planning on using the PV inverter assistant which I assume would add a level of safety. The purpose of the Victron would be provide a pseudo grid as the ME3000 is a grid tie inverter but this system would not be connected to the utility grid. I am hoping a small battery is enough to initialise the Victron and once active the Me3000/PV/battery would keep the system going.
Is there a formula to determine minum battery size?
Just realised diagram was incorrect so see revised.
Formula for minimum battery sizing is 3000/48v =62.5A continuous rating of bank.
With the revised diagram, the inverter will technically be supporting all loads downstream now in case of grid failure. If PV drops off where does the power draw from? The Victron system since that is the source. The ME is connected through the Victron to the grid, so would not drop to inverting since the Victron is now the grid.
Maybe you could connect the SOFAR to the AC2 out of the Victron and on grid failure so it will disconnect from the Victron so that the Victron is not supporting the loads there? Or will that affect your wiring as well?
How does the SOFAR react to frequency shifting? I have never used one.
I'm thinking the Sofar is complicating matters and maybe the following is a better option, I think it would be ok and as far as I can determine the grid tie inverter works with frequency shifting, (SolarMax 4200S.)
How did it go with the Sofar inverter? I'm planning to attach a Sofar 3000 ktlm-g3 to AC-OUT2 of a Multiplus II 5kVA.
I was wondering if the 1:1 ratio still applied in the situation below (see diagram) if the system is off grid and the batteries are connected to the Sofar. Thanks.
To answer this question, yes the 1:1 rule applies to all AC coupled systems where the PV inverter is behind the Victron inverter and there is no grid present. The reason is that the Victron inverter has to be able to handle the full power the PV inverter could deliver.
