Multiplus 2, Virtual Switch and PV Inverter Assistant

Anyone else been down the rabbit hole of trying to get the Virtual Switch and PV Inverter Assistant playing nicely together on a Multiplus 2?

Running a 48V system on the narrowboat — Victron Multiplus 2, Cerbo GX, Fogstar Drift LiFePO4 cells, and a Victron MPPT on the main array. All lovely and well-behaved. Then I bolted on a second AC-coupled inverter for a second array and suddenly the whole thing has the personality of a disgruntled badger.

The issue I keep bumping into: the Virtual Switch logic seems to get confused when the PV Inverter Assistant is also trying to manage frequency shifting to curtail the AC-coupled array. They're both poking the Multiplus at the same time and the result is... chaotic. Grid relay chattering, unpredictable behaviour when the batteries hit absorption — the usual carnival.

Victron's own documentation basically hints that mixing assistants can cause grief, but doesn't exactly shout it from the rooftops, does it.

A few questions for the hive mind:

• Has anyone successfully run both assistants simultaneously without wanting to throw the Cerbo overboard?
• Is the consensus just to ditch Virtual Switch entirely and let ESS handle it, or does that open a different tin of worms?
• For those AC-coupling a Fronius or similar on a pure off-grid setup, what's your curtailment strategy actually looking like in practice?

Feels like there should be a cleaner solution and I'm probably missing something obvious — or Victron's assistant stacking is just genuinely a bit of a mess. Wouldn't be the first time.

Hey @48VQueen, yes absolutely been there! The key thing I found was that the PV Inverter Assistant needs to be loaded first in the assistant stack before Virtual Switch — order genuinely matters and the manual glosses over this completely.

Also worth checking your AC input current limit settings aren't fighting each other when the Virtual Switch tries to hand off. On my setup I had the VS trying to disconnect shore power whilst the PVI assistant was still expecting grid reference for anti-islanding — caused some really frustrating behaviour before I sorted it.

What's your current assistant loading order? And are you on the latest firmware? There were some fixes around 497 onwards that helped stability considerably on my Multiplus 2 48/5000.

Narrowboat installs are brilliant but the AC coupling adds a layer of complexity for sure! 🚤

@48VQueen what a headache this combo can be. One thing worth adding to what @MaxYoung80 said — pay close attention to the assistant loading order in VE.Configure. The PV Inverter Assistant needs to sit above the Virtual Switch in the stack, otherwise the VS can override the PV assistant's decisions during grid-edge transitions and you get phantom disconnects.

Also had grief on my van build where the ignore AC input condition in the Virtual Switch was conflicting with the AC-coupled PV fallback logic. Ended up logging data through VRM portal for a week before spotting the pattern.

Narrowboat setup might have extra complexity if you're switching between shore power and inverter mode regularly — what's your AC input source config set to?

Something I learnt the hard way on my static caravan setup — when the Virtual Switch is doing its thing based on SOC thresholds, it can momentarily confuse the PV Inverter Assistant about whether the grid is "present" or not.

That split-second transition caused my AC-coupled Fronius to trip repeatedly until I added a deliberate time delay in the Virtual Switch conditions. Even just 2-3 seconds made a massive difference to stability.

Also worth checking your AC input current limit settings don't conflict with what the assistant expects to see during the handover — that caught me out for a solid afternoon of head-scratching before I spotted it in the VEConfigure logs.

@48VQueen narrowboat installs have their own quirks with shore power availability too, so that transition behaviour really matters for you.

Good points from @MaxYoung80 and @JubileeClipHero5 already.

One thing I'd add from my boat setup — watch out for the AC input current limit interaction. When the Virtual Switch disconnects shore power, the PV Inverter Assistant needs a moment to "see" the new grid-forming situation. If your assistant polling interval is too slow you can get a brief window where the MP2 gets confused about available power.

Also worth checking your assistant loading order in VEConfigure — it genuinely matters which one sits higher in the stack.

I run mine with a small ignore AC input timer buffer (around 2-3 mins) to let things settle after switching events. Massively reduced false triggers on my system.

If you're on a narrowboat and running a shore power hookup at marinas, also make sure your PowerAssist settings are sensible — it interacts with this whole chain too.