I am designing a system that will use two 12/3000 Multiplus units on a boat. All equipment on board is 120V. However, the AC system on the boat is flexible in that it can be connected to an onboard split phase generator that produces 240V/120V, up to 37A per leg, or connected to 240V/120V split phase shore power, up to 50A per leg. Additionally, it can be connected to 120V single phase up to 30A total. The selection for each of these sources is done via input breakers with mechanical lockouts so that only one source can be connected at a time. When connected to the 120V/30A power source, the two legs are combined so that one leg feeds both halves of the AC panel. When connected to a 240V/120V split phase source (generator or 50A shore), the legs are separate and each leg feeds half the 120V panel. I realize that this system is unconventional but it allows great flexibility when traveling to different docks, and it is a system requirement to keep this flexibility. Obviously, when using the 120V/30A source, you must be careful not to turn too many things on, but this is not problematic.
I am thinking that I would set the system up to operate in split phase mode, and when connected to one of the split phase sources (generator or 50A shore), it seems that it would be straightforward, even if it is completely immaterial to the operation of the equipment on board whether its power is in or out of phase with other pieces of equipment on board (again, all equipment is 120V). However, I am not sure what happens if they are set up to operate in split phase mode and are fed with power that is in-phase (as would happen when connected to a 30A/120V source). Conversely, parallel operation would work well when connected to 30A/120V sources but not work when connected to one of the split phase sources.
I’m also curious how digital multi control units work with systems that have two multiplus units? Do you use 1 or 2 digital multi controls? Perhaps you can choose whether to use 1 or 2?