Here are the ways you can use two MultiPluses in USA RV parks.
[1] You can run them both completely independently, and then you need two CCGX, etc., if you want the full stack of monitoring and visualization.
[2] You can run them in a parallel "stack" and unify your load centers. The advantage of this is that you get the full power distribution across the whole set of loads. The downside is you cannot run 240V appliances, they run or fail as an atomic unit, and your minimum shore current in assist mode is twice the specified minimum for a single unit. You must wire both units to the same leg when you are on a 50A supply, so you will have a maximum of 6kW shore power available on 240V shore supplies.
[3] You can run them in a split-phase pair. There are two advantages of this approach compared to stacking. First, your two units are wired to each phase when on a 240V supply, so you have access to the full 12kW at the pole, subject to the internal limits of your MultiPluses. (They won't be able to charge that much, for example.) Second, if you have a single phase supply (120V 30A, 20A, 15A), you can feed it to one side and the other side will reject incoming and stay in inverter mode. You will have seamless load support on both legs, but you will be going through the battery for the second leg. A consequence of this setup is that if you have a large 120V generator, you may not be able to fully utilize it, because it can only feed one of your two units.
Which you should choose is pretty situational. Some examples:
- If you mostly have loads that total less than 6kW (hint: you do, if you live in a regular RV), you could choose [2] for the max power delivery flexibility.
- If you have 240V loads, you must choose [3].
- If you regularly use very small shore supplies, like say a 100-foot extension cord connected to your friend's 15A exterior outlet, you may need to chose [1] or [3] so that you can set a low enough shore limit.
- If you value having a quick failover in the event of a unit that dies, [2] gives you the cleanest path to bring your entire set of loads back online.
- If you have a large 120V generator relative to your selected MultiPlus size, you cannot choose [3] if you wish to use the generator's full capacity.
If you're willing to add components, you can achieve the benefits of [2] while using [3] by adding an autotransformer on the output side of the inverters.
It's not too hard to toggle between these three modes, as long as your two inverters are the exact same model and hardware revision level. You could experiment with one approach and change down the road if you don't like the consequences.
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