HUAWEI SUN2000-5KTL-L1 , bzw. SMA Sunny Boy 5.0-1AV-41 mit Victron MP2 im Offgridmodus kompatibel?

Been doing a lot of research lately on pairing AC-coupled solar inverters with my Victron Multiplus II setup at the static caravan, and I keep coming back to the same question — which grid-tie inverters actually play nicely with Victron's frequency shifting in off-grid mode?

The original discussion that inspired me to post was around the Huawei SUN2000 and SMA Sunny Boy ranges, and whether the Cerbo GX can properly regulate them when there's no grid connection. This is exactly my concern.

From what I understand, Victron's off-grid frequency shifting works by the Multiplus II raising the AC output frequency when the batteries are full, signalling the grid-tie inverter to throttle back. But this only works if the inverter actually responds to those frequency deviations — not all of them do, or at least not without specific firmware settings.

A few questions for anyone who's done this:

• Has anyone successfully run a Huawei SUN2000-5KTL-L1 or similar in AC-coupled off-grid with a MPII? Does it respond to frequency shifting properly?
• Same question for the SMA Sunny Boy range — I've seen mixed reports
• Is there a go-to inverter brand/model that works reliably in this scenario without endless faffing?

I've seen the Victron compatibility list but it feels a bit sparse. Wondering if Fronius is still the gold standard for this kind of setup, or whether others have had success with alternatives that are a bit easier on the wallet.

Would love to hear from anyone running an AC-coupled system in a cabin or off-grid property — real-world experience is worth so much more than spec sheets here.

Purely anecdotal but ran a SMA Sunny Boy AC-coupled with my Multiplus II on the narrowboat for two seasons — the 1:1 rule (solar inverter VA ≤ Multiplus VA) is your best mate here, otherwise the frequency-shift curtailment goes absolutely haywire when the batteries are full and you'll be watching your Victron throw a wobbler at 2am.

Huawei's a bit of a wildcard in my experience — their frequency response isn't always as snappy as SMA's when the MP2 tries to curtail via the 50.2–51.8Hz trick, so if you value your sleep more than saving fifty quid, stick with the Sunny Boy.

Check the Victron ESS compatibility list — it's basically the Bible for this stuff and saves you buying expensive paperweights.

Great thread, @SueJohnson. Worth noting that the Huawei SUN2000-L1 series uses a proprietary frequency-shift response curve that doesn't always play nicely with Victron's frequency shifting mechanism out of the box — you'll likely need to dig into the SDongle settings or use the RS485 port to get the power ramp-down behaviour behaving properly.

The SMA route that @WheresMeWires87 mentioned is generally the path of least resistance for Victron AC-coupling, largely because SMA's frequency-shift response is well-documented and Victron's own compatibility notes reference it directly. That said, the Huawei can work — just expect more fiddling during commissioning.

Either way, make sure your battery bank is large enough relative to the inverter rating — that 1:1 rule is there for good reason, especially off-grid where you've no grid to absorb excess.

Ran a Huawei SUN2000 alongside my Victron MP2 for about three weeks before I wanted to throw the whole lot into the Solent. Huawei's frequency-shift behaviour is deeply opinionated — it wants to talk to its own ecosystem and doesn't much care what Victron thinks about that. Like inviting someone

Great thread. Just to add to what @TimGraham was touching on regarding the Huawei frequency-shift behaviour — from what I've seen discussed on the Victron community forums, the SUN2000-L1 series doesn't always play nicely with the MP2's frequency shifting because of that proprietary curve. The SMA Sunny Boy, on the other hand, follows a more standard response and is actually on Victron's own compatibility list for AC coupling, which counts for a lot when you're troubleshooting at midnight in a field somewhere.

@AZY_Marine's experience doesn't surprise me honestly. If you do go SMA, make sure you've got the frequency settings dialled in correctly on both sides — there's a good walkthrough in Victron's AC coupling documentation that covers the power management ratio rules. Worth reading before you commit to anything.