Dynamic power limiting, off grid

Been scratching my head over something similar with my Victron setup lately, so this feels timely.

I've got a Multiplus-II running ESS on a cabin install — completely islanded, no grid connection whatsoever. Set it to Optimised without BatteryLife and noticed the dynamic power limiting figure sitting at a stubbornly large number that bore no relation to what my system could actually deliver. Felt like the ESS logic was still assuming a grid-tied scenario and hadn't quite "let go" of that assumption.

My suspicion is that dynamic power limiting in ESS is fundamentally designed around grid presence. It's there to prevent export or manage draw relative to the grid — so when you yank that reference point away by going fully off-grid, the algorithm loses its anchor and either defaults to something nonsensical or just stops adjusting meaningfully.

What I ended up doing was shifting my thinking away from ESS entirely for the off-grid cabin and leaning more on the DVCC settings and charge current limits to manage things properly. Works a treat once you stop fighting ESS's grid-centric assumptions.

That said, I'd genuinely love to know if anyone's cracked this properly within ESS — particularly if you've got a PV inverter on AC-OUT rather than MPPT on the DC side. The AC-coupled side adds another layer of complexity with the frequency-shift power control kicking in.

Anyone else running a fully islanded ESS setup and found a cleaner way to handle this? Curious whether it's a firmware quirk or just a fundamental limitation of how ESS is architected.

@OffGridTerry ESS on a fully islanded system is basically giving your Multiplus an identity crisis — it's a grid-tied brain in an off-grid body. 🧠

You want PowerAssist mode instead, which actually makes sense when there's no DNO to phone home to. ESS keeps hunting for a grid reference that simply doesn't exist.

Swap it over in VictronConnect, set your AC input limit to whatever your generator/source can handle, and let it do its thing properly. Works a treat on my cabin setup — Multiplus stops having an existential meltdown about missing grid voltage and just gets on with it.

@WayneTaylor makes a fair point about the identity crisis — I've been wondering though, is there a practical reason folks choose ESS over just running the Multiplus-II in standalone inverter mode for a fully islanded setup?

On my shepherds hut build I went standalone from the start and the power limiting side of things is handled through the DVCC settings in VenusOS — is that not an option on a cabin scale install @OffGridTerry?

Genuinely curious what the advantage of ESS brings here if there's no grid to export to or import from. Does it give you better battery protection algorithms or something? The Victron documentation gets a bit murky once you're outside the "normal" use case and I've never found a clear comparison between the two approaches for fully off-grid scenarios.

@OffGridTerry the Multiplus-II in ESS without a grid is essentially a Formula 1 car doing the school run — technically works, but you're fighting the engineering the whole way.

If you're fully islanded, Quattro or plain Multiplus in standalone inverter/charger mode with VE.Configure is usually the saner path — lets you set dynamic power limits properly without ESS throwing a wobble every time your fridge compressor kicks in.

Victron's own docs quietly admit ESS wants a grid reference to behave itself; without one you're wrestling with phantom grid codes.

@OffGridTerry @SussexBoater has hit the nail on the head with that analogy! What you actually want for a fully islanded setup is the Multiplus-II in standalone inverter/charger mode rather than ESS. ESS really is designed around the assumption there's a grid connection somewhere in the picture.

For dynamic power limiting off-grid, have a look at configuring it through VEConfigure with a battery monitor feeding SOC data — you can set up assistants to throttle loads based on battery state without needing ESS at all. The "Self-consumption Hub" assistants are worth exploring too.

What's your battery chemistry and BMS situation? If you've got a compatible BMS talking to the Multiplus via VE.Can or VE.Bus, a lot of this can be handled quite elegantly without ESS muddying the waters. Cerbo GX in the mix?