Dynamic PV Inverter limiting - Multiple Inverters from different brands

Been down this rabbit hole recently with my motorhome setup and thought it was worth opening up here for a wider chat.

I'm running a Victron Multiplus-II alongside an older Renogy inverter-charger that I picked up secondhand — bit of a Frankenstein system, I'll admit. The Victron side plays nicely with Venus OS and I've got dynamic PV limiting working through the GX device, but the Renogy just sits there doing its own thing, completely unaware of what the Victron is doing.

The core problem is obvious: when the grid (or in my case, a site hookup) can't absorb excess export, Venus OS can throttle the Victron-connected MPPT controllers — but it has no visibility over anything connected purely to the Renogy side. So you end up with a lopsided system where one half is being sensibly managed and the other is just pushing whatever it likes.

Has anyone actually solved this with a mixed-brand setup? A few approaches I've been thinking through:

• Using a Carlo Gavazzi energy meter to give Venus OS full site visibility and let it react to total generation rather than just its own slice
• Some sort of external relay control on the non-Victron inverter
• Just... consolidating everything onto Victron and being done with it 💸

I suspect the "proper" answer is the last one, but that's not always realistic financially.

Would be really interested to hear from anyone who's managed to get dynamic limiting working across genuinely mixed hardware — especially if you've done it without ripping everything out and starting again.

@Stacey mixed-brand dynamic limiting is genuinely tricky. The core issue is that Victron's ESS assistant uses VE.Bus/DVCC to throttle the Multiplus cleanly, but your Renogy has no way of receiving those signals — it's essentially invisible to the system.

What I did on my van build was put a Zigbee smart meter on the grid/shore connection and use Node-RED to bridge the readings across. Not plug-and-play though.

Worth asking:

• Is the Renogy on a separate DC input or sharing the same battery bank?
• Do you have a Cerbo GX or similar in the loop?

Without a common communication layer, you're basically relying on the battery BMS to act as the ultimate limiter — which works but isn't elegant. Victron's DVCC can at least enforce charge current limits if everything talks to the Cerbo.

@Stacey this is exactly the mess I ran into when I was setting up my shepherd's hut. Ended up with a Victron MPPT feeding into a system that had a legacy inverter on it and the dynamic limiting just... ignored half the array half the time.

The bit nobody mentions is that zero-export limiting only works cleanly when everything speaks the same protocol. Mixing brands means you're essentially doing it manually or writing Node-RED flows to bridge the gap.

What I eventually did was use a Shelly EM on the grid connection feeding CT data into Venus OS, then scripting the legacy inverter's output limit via its Modbus interface. Messy but functional.

What comms does your Renogy unit actually support? Some have Modbus, some have nothing useful at all — that's usually the deciding factor on whether bridging is even viable.

Worth adding — in my shepherd's hut I just gave up trying to bridge the two protocols and kept the non-Victron kit on a completely separate circuit. Crude but it works reliably.

The Victron ecosystem does play nicely with itself once you've got a Cerbo GX as the hub, and you can do proper dynamic limiting through that. Anything outside that bubble though, you're basically bodging it.

If budget allows, @Stacey, swapping the Renogy unit out for even a second-hand Victron might save a lot of headaches long-term. Marketplace here occasionally has them going reasonably.

@LochChild that's probably the most pragmatic solution tbh — isolating the non-Victron gear onto its own sub-circuit rather than trying to bodge comms between incompatible protocols.

One thing worth considering though: if you're using a Fronius or SMA unit alongside Victron, there's actually native support via Frequency Shift Power Control (FSPC). The Multiplus-II modulates grid frequency to signal the AC-coupled inverter to throttle back — no shared comms protocol needed.

For genuinely mixed setups without that luxury, an OpenEVSE or custom Node-RED flow on a Cerbo GX can act as a soft bridge, reading Victron MQTT and firing relay outputs to dumb-down control the secondary inverter.

Not elegant, but it works. Done something similar on my backup setup to manage a legacy unit that had zero smart capability.