Hi Is it possible to have two Multiplus II inverters in parallel and have one inverter shutdown when one inverter can supply the load, and turn on when the load increases? Thanks
I’ve not done this so YMMV…
But I would use ESS’s Generator Control assistant to control the relay in MP #1 and connect that to the aux input on MP #2. Set MP #2’s aux input as a switch to “Ignore AC Input”. Program MP#1’s ESS assistant to “turn on the generator” when the load increases above whatever value you want it to. It triggers the relay which MP#2 is listening to and when that relay is triggered, MP#2 stops ignoring the AC input then starts doing whatever you programmed it to do. MP#2 will always be the slaved unit so will be doing less work - I’m guessing this isn’t an issue but I don’t see an easy way to have them swap roles to balance the lifespan of the units (assuming this has any effect on the lifespan at all - it probably doesn’t).
EDIT: this is all assuming that you can run different ESS assistants on both units when they are working in parallel. If that’s not the case, you would probably have to use the same ESS assistant but have it control an external contactor controlling the MP#2 AC input.
Parallel units operate as one virtual device. They cannot be operated independently in a parallel configuration.
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Derrick is correct.
When they are programed as one they are one system they behave as one (even though physically there are two units)
What would happen if one unit’s AC input was disconnected in this arrangement?
They switch as a group, they behave as if they are one.
Unless you deactivate that with the VE.Bus system configurator. 
Lol, yes true. I suppose it depends on if Bluey wants ESS or not as well.
Thank you to all for the invaluable replys.
Two AC Outputs
The main output has no break functionality. The MultiPlus takes over the supply to the connected loads in the event of a
grid failure or when shore/generator power is disconnected. This happens so fast (less than 20 milliseconds) that computers
and other electronic equipment will continue to operate without disruption.
The second output is live only when AC is available on the input of the MultiPlus. Loads that should not discharge the
battery, like a water heater for example can be connected to this output (second output available on models rated at 3 kVA
and more).
Update on my problem: I just watched a utube, that the OUT AC 2 can be programmed to operate when the battery gets to a nominated voltage and turn off when the low voltage is reached. AC In is not required to have this function work. Is anyone using this OUT AC2 function in this way? It does appear misleading that Victron says The second output is live only when AC is available on the input of the MultiPlus Any have a comment of this ? Thanks
In default programming it is this way so referring to its base state.
Which you know is possible to change with programming as it almost everything else. Yes i program ac2 out for use on battery state of charge for many systems.