Multi RS Solar plus Multi RS -- common Vbatt and ACIN (mains/generator), separate ACOUT

Been doing a fair bit of reading on this lately and it's got me thinking about my van build — though I reckon this applies just as much to static off-grid setups.

So the Multi RS Solar (and the newer Multi RS) can't be paralleled at the AC output because they can't sync with each other, fair enough. But what if you deliberately keep the AC outputs separate while sharing a common battery bank and a common AC input (mains or genny)?

Basically the question is: is that a valid and safe configuration? Two units, same Victron battery system (say a 48V LiFePO4 bank, Fogstar or similar), both pulling from the same AC input when available, but each feeding its own independent AC output circuit.

My thinking is this could be genuinely useful where you've got:

• One circuit for sensitive loads (NAS, networking, medical kit)
• Another for "rough" loads (power tools, kettle, etc.)

And you'd get double the inverter capacity without needing true parallel sync.

A few things I'm not clear on though:

1. Does the battery management get messy with two units on the same bank — any contention issues?
2. Would both units play nicely together in VictronConnect / Venus OS without one trying to override the other?
3. On a shared AC input, does one unit effectively "steal" charge priority from the other?

Has anyone actually tried this or seen it running in the wild? I've seen vague references in the Victron Community forum but nothing conclusive for a UK-spec setup. Would be dead useful for an off-grid cabin or a large van build with segregated loads.

@Thommo9 curious where you're going with this — are you thinking about load prioritisation between the two ACOUT circuits, or is it more about fault isolation?

On my narrowboat I've been mulling something similar. The appeal of separate ACOUT legs is obvious if you want critical loads (bilge pump, fridge) on one circuit and "nice to have" stuff on another, but I'm not sure how the Multi RS handles the inverter load sharing when both units are pulling from the same battery bank simultaneously.

Does Victron's documentation actually confirm they'll parallel properly on the AC input side whilst keeping ACOUT independent? Or does that require specific firmware and VE.Bus configuration? The GX device integration side of it worries me slightly too — does each unit show up as a separate device, or does Venus OS treat them as a combined system?

@Thommo9 done something loosely similar in my shepherd's hut — two Victron units sharing DC bus, separate AC outputs for different circuits. Main thing I'd flag is getting your ESS config right if you're on mains assist, otherwise they can fight each other a bit.

@DerekMoore89 load prioritisation is definitely the interesting bit — in my case I just physically split it (essential stuff on one output, "nice to haves" on the other) rather than trying to get clever with the software. Simpler to troubleshoot when something goes wrong.

Haven't played with the Multi RS Solar specifically, more familiar with the standard Multis. Curious whether the built-in MPPT on the RS changes the shared DC behaviour at all — anyone actually tested that with two units on the same bank?

@AnneWatson that's really interesting about the shepherd's hut setup — I'm trying to work out something similar for my cabin. My main question is around EV charging on one of the ACOUT legs: if the generator kicks in as ACIN to both units simultaneously, does each unit's ACOUT become "generator-backed" independently, or does one unit effectively become the master and the other follows?

Practically speaking, I don't want my EV charger (on a dedicated ACOUT) pulling generator power unexpectedly when battery is low — I'd rather it shed that load entirely. Has anyone managed this through VictronConnect or do you need Venus OS / Node-RED logic to handle the load prioritisation properly?

@Thommo9 this is exactly the rabbit hole I went down when planning my narrowboat fit-out. What tripped me up initially was assuming the two units would just "sort themselves out" on ACIN — they don't, not without careful attention to the ESS assistant configuration and making sure your VE.Bus is properly coordinating them.

The shared DC bus side is actually the straightforward bit; Victron's architecture handles that gracefully. It's the ACOUT separation that needs deliberate planning — think about what lives on each output and how those loads behave during a grid dropout or generator transition.

@GemmaWood and @AnneWatson — with a static setup like a cabin or caravan, you've got more physical space to keep wiring tidy between units, which genuinely helps during fault-finding later. What's the intended split between your two outputs?