Add a battery inverter via Node Red?

Been down a bit of a rabbit hole with this one and wondering if anyone else has tried it.

My static caravan setup runs a Cerbo GX with a couple of Victron SmartSolar MPPTs and a Fogstar Drift 100Ah connected via CAN bus. No inverter/charger in the mix — just solar feeding the battery directly. Works fine for my needs most of the time.

What I'm now wondering is whether I can pull battery data through Node-RED on the Cerbo and use it to trigger/control a standalone inverter that isn't natively part of the Victron ecosystem. Basically a dumb inverter that just needs a switched signal to enable or disable it based on SOC thresholds.

A few questions for anyone who's done something similar:

• Can Node-RED on the Cerbo actually write to a virtual switch or relay output based on MQTT battery data from the BMS?
• Has anyone used the Cerbo's programmable relay this way rather than buying a full Multiplus?
• Is there a risk of the VRM portal throwing fits if you've got components it doesn't recognise being toggled via automation?

I'm trying to avoid splashing out on a Multiplus when the solar + BMS setup already does exactly what I need — it's really just that last piece of "turn the inverter off before the battery tanks" that I'm missing.

Feels like Node-RED should be able to handle this but I've not found a clean example for a UK setup anywhere. Anyone done it?

@LisaStewart71 yeah done something similar on my shepherd's hut setup — Cerbo GX is brilliant for this kind of thing tbh

The Node-RED flows on VenusOS can talk to pretty much anything if you're patient enough. I got a cheap inverter wired in via a relay and used a virtual switch triggered off SOC thresholds. Bit janky but works

Main gotcha I found — make sure your DVCC settings aren't fighting what Node-RED is trying to do, caused me a right headache for about a week before I figured that out 😅

What inverter are you looking at adding? If it's Victron it'll be dead easy via the GX, if it's a random unit you'll probably be triggering it externally rather than proper comms

@LisaStewart71 ooh yes! Done exactly this on my narrowboat actually 🙌

Cerbo + Node-Red is such a good combo. I've got a flow that watches the com.victronenergy.battery MQTT topics and triggers my inverter based on SOC thresholds — works a treat.

Few things worth knowing:

• Make sure you're on a recent Venus OS version (Node-Red gets updates fairly regularly)
• The Keep batteries charged vs Optimised modes can interfere with custom logic if you're not careful
• Fogstar Drift plays nicely once the BMS comms are sorted

The VRM portal also lets you check your flows aren't doing anything daft remotely, which saved me once when I'd set a dodgy threshold 😅

What inverter are you trying to integrate? Makes a difference to which MQTT topics you'll be poking at.

Looks like Lisa's post got cut off so not 100% sure what she's actually asking, but if it's about adding a non-Victron inverter into the Node-Red flows on the Cerbo — it depends heavily on the inverter's comms options.

If it's got Modbus TCP or RS485 you can usually pull data into Node-Red via a custom node and then write logic around it. I've done something similar in my garden office setup bridging a non-Victron device alongside the Victron kit.

Worth checking the Venus OS Large image is installed first — that's what unlocks Node-Red on the Cerbo.

Also, @PanelKate — curious what you're doing on the narrowboat, sounds like it might be relevant here.

@LisaStewart71 if you can repost the full question it'd help narrow things down.

@LisaStewart71 looks like your post got clipped but I'm guessing you're asking about integrating a non-Victron inverter into the Cerbo's ecosystem via Node-Red? Done something similar on my motorhome actually — I've got a Victron Multiplus but I experimented with Node-Red flows to trigger relay outputs based on SOC thresholds.

The key thing to know is Node-Red on the Cerbo can read pretty much any MQTT topic from the VRM local broker, so if your inverter has modbus or serial comms you can bridge the data across. @Wez1961 is right to flag the non-Victron angle — it gets fiddly fast.

What inverter are you adding? That'll determine whether you're looking at a proper modbus integration or more of a workaround using the Cerbo's digital inputs. Makes a massive difference to how clean the solution ends up being.