ESS erreicht Netz-Sollwert nur bei aktivierter AC-PV-Überschusseinspeisung

Bit of a niche one this, but I've been down a rabbit hole with my Victron MultiPlus-II ESS configuration and I think others running similar setups might have hit the same wall.

So here's the scenario. I've got the MultiPlus-II 48/5000 paired with a Fronius inverter on the AC output side. Everything ticks along nicely until I start looking at how the ESS actually hits its grid setpoint. I noticed it would only properly regulate to my target import/export figure when I had AC-coupled PV feed-in enabled. Switch that off, and the regulation goes a bit wonky — it's like the ESS logic can't quite settle on the setpoint without that feed-in pathway being active.

Now I appreciate this is technically a single-phase MultiPlus on what's nominally a three-phase supply situation, which adds another layer of complexity. The DVCC settings and the grid setpoint interaction don't always behave the way the Victron documentation implies they should.

My Fogstar batteries are perfectly happy throughout, so it's not a BMS comms issue. This feels more like an ESS firmware quirk or possibly a configuration order-of-operations thing.

Has anyone else seen ESS grid setpoint regulation behave differently depending on whether feed-in is active? I'm particularly curious whether tweaking the minimum SOC or the grid setpoint value itself changes anything, or whether this is just a known limitation when you're running single-phase in a three-phase environment.

Would love to know if anyone's found a workaround that doesn't involve leaving feed-in permanently enabled.

@PanelLouise the thread title's in German but I'll assume the gist is the ESS not hitting its grid setpoint unless AC-PV feed-in excess is enabled?

Had exactly this on my cabin MultiPlus-II 48/3000. The ESS grid setpoint was being ignored until I enabled feed-in excess solar in the settings — even though I didn't actually want to export.

From what I can tell, the ESS assistant needs that option active to properly close the control loop on grid power. With it off, the system seems to just... drift.

Worth checking your DVCC settings too — I had a conflict there with my BMS (Fogstar Drift cells, custom BMS) that was muddying the waters.

What firmware are you running? There were some ESS quirks fixed around v2.9x on the CCGX/Cerbo side.

@PanelLouise the thread title gave me a mild panic — thought I'd accidentally wandered onto a German engineering forum 😅

But yeah, this rings a bell from when I was fiddling with my MultiPlus-II last winter. ESS can be a bit precious about hitting its grid setpoint — it essentially wants all its ducks in a row before

@PanelLouise Google Translate did us all a favour there — roughly "ESS only reaches grid setpoint when AC-PV feed-in excess is active," for those playing along at home.

Genuinely interesting one this. I've seen similar behaviour on my MultiPlus-II 48/3000 where the ESS grid setpoint gets effectively ignored unless certain feed-in conditions are met. Worth checking your ESS Assistant version and whether you have Optimise (with BatteryLife) mode selected — that mode can absolutely override your setpoint when the system decides it knows better than you, which is both impressive and infuriating in equal measure.

Also, what's your AC-PV coupled through? If it's an external inverter on AC-out, the MultiPlus's visibility of that generation is limited, which can cause the setpoint logic to behave oddly. VRM logs would tell you a lot here.

@CliveBaker yes cheers for the translation, some of us have enough trouble configuring ESS in English without Victron's documentation doing an impromptu Deutsch detour.

For what it's worth on the actual issue — classic symptom of the MultiPlus-II not having enough headroom to hit the grid setpoint when AC-PV is constrained; check your ESS minimum SOC and whether your BMS is throttling charge current before the inverter even gets a look-in. Victron's own ESS manual (buried about 47 pages deep, naturally) covers the AC-coupled feed-in priority behaviour. If you're on an older firmware, update it — fixed a similar quirk on my static caravan backup setup that had me pulling my hair out for a fortnight.