According to the instructions for parallel systems:
The MultiPlus-II 8k, 10k and 15k models may only be connected in parallel using an external AC power switch. For further information, please refer to the user manual for the MultiPlus-II external power switch.
Although the VE.Bus system configurator allows you to configure a system using Multis units (each with a single AC input) that is configured to have multiple separate AC inputs, such a system is not supported by GX units.
The VE. Bus System Configurator allows configuration in a three-phase parallel system, with two Multiplus 8000 units per phase. Given a maximum input current of 32 A, can such a system be used without voiding the warranty and without an additional external transfer swich? The standard Multi transfer swich is rated for 100 A
Any explanation? The manual doesn’t explicitly rule out a parallel setup for the Multi 8k; in fact, it even states that VE Config will allow you to configure it, but it won’t work with GX.
The MultiPlus-II 8k, 10k, and 15k models can only be connected in parallel if an external AC transfer switch is used. For
more information see the MultiPlus-II External Transfer Switch application manual .
The issue with these devices is not about the rating of the relays.
If you are entirely off-grid, with zero AC generation, then you can, technically, parallel them, as others have done.
If you intend any form of AC generation, you will require the ATS for reliable operation and warranty.
In a parallel system, several inverters would need to switch multiple relays at exactly the same instant. Small wiring delays make that impossible in practice. Using a single external disconnect relay means the whole system switches together, avoiding synchronization issues. It’s a simpler and more reliable engineering solution.
What is the difference between the Multiplus-II 5000 and 8000 in this context? With one, you can do without an external unit, with the others, you cannot.
That would be a question for your supplier or regional manager that can provide those answers to you.
As a community and not an ask victron/support site we can’t give you an official answer.
As far as I am aware it is related more to consistent timing of input relay operations, which is why the solution is to disable them and use an external device.
The docs say no, so no it is.
What you do at your own risk is your choice, but there will be no warranty.
They would not have gone to such an extensive piece of test and development to certify this ATS solution just for the heck of it.
Size power safety and longevity of set up.
The input relays and some inverters have been destroyed in parallel set ups from the slight delay in disconnecting.