Configuration mesure de courant pour PV inverter sur AC-OUT Multi+2-GX

Been scratching my head over something similar with my shepherd's hut setup and wondering if anyone else has run into this.

Running a Victron Multiplus-II GX 48/3000 with a stack of Fogstar Drift 48V lithium packs and a couple of Renogy panels through a SmartSolar MPPT. Works an absolute treat most of the time — but I recently bolted on a small AC-coupled inverter on the AC-OUT side to squeeze a bit more from some second-hand panels I picked up at a farm auction.

The bit that's doing my head in is current measurement configuration. With the AC-coupled inverter sitting on AC-OUT, I'm not entirely convinced the GX is reading the combined AC load and PV feed-in correctly. The VRM portal figures look a bit off compared to what my clamp meter is showing on the physical cables.

From what I can gather, you need to configure whether the current transformer is measuring grid side or load + PV side — and getting that wrong means the ESS logic makes some bizarre decisions about when to charge or discharge the batteries.

A few questions for the collective brain here:

• Has anyone successfully set up a CT clamp or EM24 meter on AC-OUT with a Multiplus-II GX and an AC-coupled inverter?
• Did you need to tweak anything in the ESS assistant settings to account for the additional PV source?
• Any gotchas around the frequency shift / Volt-Watt response with the AC-coupled unit?

The Victron documentation feels a bit patchy on this specific combination. Would love to hear from anyone who's cracked it.

@GaryParker97 Ooh this one takes me back — spent a whole wet weekend in a layby near Inverness trying to figure out why my current measurements were all over the place on my motorhome setup.

The key thing I found with AC-OUT connected PV inverters on the Multi+ GX is making sure your CT sensor is positioned after the Multiplus output, measuring the full combined load. If it's sitting in the wrong place, the GX just gets confused about what's genuinely being consumed versus what's being back-fed.

In VEConfigure, double-check your AC sensor assistant is actually enabled — it's not on by default and catches people out constantly.

Also worth confirming whether your PV inverter is set as "AC-IN" or "AC-OUT" in the GX device list, because that completely changes how the energy flow gets calculated and displayed.

Bit hard to advise without knowing your full config, but a couple of things worth checking:

1. Are you using an ET112 or ET340 energy meter on the AC-out? Without it, the GX has no way to see what a grid-tied PV inverter is actually doing on that leg.

2. In VRM/Venus, make sure the meter is set to "PV inverter on AC-out" — not AC-in. Easy mistake, changes everything.

I had similar grief on my static caravan setup before I got the role assignment right in the device list. The Multi kept second-guessing its own output once I added a Fronius.

What's your ESS or self-consumption assistant configured as? That can shift behaviour significantly depending on whether you're in island mode or not.

Good shout from @DucatoProject on the ET112. One thing worth adding — if you've got a PV inverter on AC-OUT, make sure you've set ESS Assistant correctly and told the system where that inverter sits in the grid code settings.

Specifically:

• Set PV inverter on output in the ESS config
• Check your AC-IN current limit isn't fighting the PV contribution
• On the GX device, confirm the PV inverter is showing under Settings > Energy Meters and assigned the right role

I had a similar head-scratcher on my narrowboat before I realised the CT clamp was measuring the wrong direction entirely. Victron's own VE.Configure tool will show you exactly what the system thinks it's seeing — worth running through that before assuming hardware fault.

What does your VRM dashboard show for AC loads vs PV yield? That'll narrow it down quickly.

Good points all round from @DucatoProject and @ExFirefighter. One thing I'd add from hard experience fitting out my last motorhome conversion — if your PV inverter sits on AC-OUT, the Multi sees it as a load and a source depending on conditions, which can confuse the hell out of ESS if your assistant isn't configured correctly.

In VEConfigure, under the ESS Assistant, make sure "AC-coupled PV on output" is ticked, and double-check your Fronius/SMA/whatever's frequency shift settings match what Victron expects. The Multi uses frequency shifting to curtail that inverter when the batteries are full — if the thresholds are off, you'll either get overcharge or the inverter won't back off properly.

Also worth running VRM diagnostics overnight and watching the AC-OUT current readings. That'll tell you quickly whether the ET112 is actually reading correctly or just sitting there looking decorative.