MultIplus 6k5 als ESS zieht immer wieder Strom aus dem Netz 1 Phase

Bit of an odd one this, and I'm curious whether anyone else has run into something similar with a Victron ESS setup.

Running a Multiplus-II 5kVA at the shepherd's hut site — single-phase grid connection, Pylontech batteries, and the whole thing configured as ESS with grid tied. Most of the time it behaves itself beautifully, but every now and then I'll glance at the VRM dashboard and notice it's pulling a trickle from the grid even when the batteries are sat at 80-90% and there's decent solar coming in from the MPPT.

It's not massive — we're talking 50-150W — but it's consistent enough that it's clearly not just rounding error or sensor noise. The ESS assistant is definitely loaded, grid setpoint is configured at 0W, and I've double-checked the phase compensation settings.

My suspicion at the moment is something quirky around the AC input current limit interacting with the ESS logic, but I haven't been able to pin it down definitively. There's also a slight possibility it's related to the EV charger I've got on the same phase — a Zappi — since the load fluctuates quite a bit when a car's plugged in and the Multiplus might be compensating oddly.

Has anyone seen behaviour like this on a single-phase ESS install? Particularly interested if you've had a similar setup where variable AC loads seem to confuse the inverter's grid setpoint tracking.

Worth logging a thread here because I'd rather crowdsource this than spend another afternoon down a Victron Community rabbit hole. Drop your thoughts below — even a "yes, same here" would be useful at this point.

@Davo49 — familiar story, this one.

Had almost identical behaviour on my shepherd's hut ESS last winter. The culprit for me was the minimum SOC setting in the ESS assistant fighting with the grid setpoint — mine was nudging grid current in tiny amounts just to satisfy the inverter's idle losses calculation, even when the batteries were perfectly healthy.

Worth checking two things specifically:

1. ESS grid setpoint — default is 50W import. If your loads dip below that threshold, it pulls from the grid to compensate. Drop it to 0W if your meter/CT clamp is accurate enough.
2. AC input current limit — even at 0.1A it'll creep in.

Also, what firmware are you on? There was a known quirk in earlier Venus OS builds around single-phase ESS mode and ghost grid draw. The VRM portal current graphs will show it clearly if you zoom right in.

Had this exact headache on the narrowboat when I first wired up ESS — kept seeing small grid draws even with the batteries sitting comfortably at 80%+.

Turned out my minimum SOC and grid setpoint were fighting each other. Victron's ESS assistant essentially hunts for a zero-point on the AC input, and if your grid setpoint is set to something like -50W rather than true zero, it'll pulse-draw to compensate.

Worth checking two things in VEConfig:

• Grid setpoint (ESS tab) — try nudging it to +30W or so
• Sustained minimum current — some firmware versions have a floor you can't easily override

Also check your DVCC settings if you're running a Fogstar or similar smart lithium pack. A BMS current limit mismatch can cause the Multiplus to hedge its bets and lean on the grid unnecessarily.

What firmware are you running? That narrowed it down considerably for me.

Worth checking your minimum SOC setting in ESS — if it's set even slightly above where your batteries actually sit, Victron will quietly pull from the grid to maintain that buffer. Caught me out on my van build before I properly understood the ESS logic.

Also double-check your grid setpoint in the ESS assistant. Default is often 50W, meaning it intentionally draws a tiny amount to avoid back-feeding. Set it to 0W if your DNO allows it.

Fogstar cells or similar? Some BMS units report SOC slightly differently to what Victron sees, causing it to second-guess itself and top up unnecessarily. Calibrating the battery monitor properly sorted mine out eventually.

Hey @Davo49, good shout raising this one.

One thing I haven't seen mentioned yet — have you checked your grid setpoint in the ESS assistant? It defaults to something like 50W on many installations, which means the system is intentionally pulling a small amount from the grid constantly, just to avoid any accidental export and keep the inverter stable on a single phase.

Worth jumping into VEConfigure or VRM and setting it closer to 0W (or even slightly negative if your DNO allows export). Made a noticeable difference on my setup.

Also double-check your AC input current limit isn't fighting against the ESS logic — sometimes they interact in unexpected ways, particularly overnight when loads drop right off.

What firmware version are you running on the Multiplus-II? Some of the older ESS builds had quirks around single-phase grid interaction that were patched later.