three phase inverter for 24v battery system

Honestly this is one of those setups that makes me scratch my head a bit. Three phase from a 24v bank is a fairly awkward combination — the current draws at that voltage get eye-watering pretty quickly once you start pulling any real load.

Most of the three phase inverter options I've come across (Victron Quattro stacks, SMA Sunny Island multi-unit setups) really want to be sitting on 48v minimum, and a lot of the more serious kit prefers even higher — 96v or 120v DC bus territory. The maths just works out cleaner.

What's the actual use case here? If it's for three phase motors or machinery, there might be a simpler route depending on what loads you're running. A VFD off a single phase 48v inverter output can generate three phase for motor loads without needing to redesign your whole battery system.

If you're dead set on keeping the 24v bank, I'd be curious what capacity we're talking about. Fogstar Drift cells or something similar in a large parallel arrangement? Because the cabling and busbar situation alone at 24v trying to deliver three phase loads is going to be... interesting.

I've only ever run single phase from my own setup (48v, Victron Multiplus-II) so I'd genuinely welcome input from anyone who's actually done three phase off-grid in the UK — particularly whether you went with parallel inverters or a dedicated unit. There seem to be a few Chinese units floating around but I've not seen much real-world feedback on them.

SomersetOffGrid | Posts: 847 | Location: Taunton

@HazelPaddy spot on about the currents — at 24V you're looking at some truly brutal cable runs to keep losses manageable on a three-phase load. Worth asking what the actual three-phase requirement is for though. Genuine three-phase motors? If so, is there any flexibility to use a VFD fed from single-phase instead? That sidesteps the inverter complexity entirely in some applications.

If it really must be native three-phase, most sensible solutions I've seen involve stepping up the battery voltage first — 48V minimum, ideally higher — before the inverter stage. Victron's three-phase MultiPlus-II stacking works well but really wants 48V as a foundation. 24V into that configuration just compounds every problem you've already identified.

What's the load actually driving? That'll shape the advice considerably.

CarlCole97 | Posts: 213 | Location: Array

Had a similar head-scratcher when I was speccing out the narrowboat's system a couple of years back. Ended up stepping up to 48V specifically because the cable runs were becoming ridiculous — we're talking serious copper just to handle the peaks safely in a confined space.

Three phase at 24V feels like you're fighting the physics from the start. Even if you find an inverter that'll do it, your busbar and fusing setup is going to be a nightmare to keep tidy and safe.

Worth asking — what's actually driving the three phase requirement here? If it's a motor load, a VFD fed from a quality single-phase Victron Quattro might be a cleaner solution than wrestling a bespoke three-phase inverter onto a 24V bank that really doesn't want to play ball.

MountainHermit | Posts: 1,204 | Location: Array

Ran into exactly this trying to power a small workshop from my cabin bank a couple of years back. Three phase kit simply expects a sensible DC input voltage — most of the decent units want 48V minimum, and honestly 48V is where life gets comfortable anyway.

@CarlCole97 narrowboats have the same headache — everything's squeezed into 24V tradition but the loads keep growing.

My blunt advice: if three phase is a genuine requirement rather than a "wouldn't it be nice," redesign the battery bank first. Doubling from 24V to 48V with Fogstar Drift cells isn't the nightmare it sounds — rewire your series strings and suddenly the current figures become manageable and your Victron inverter options open right up.

Chasing three phase on 24V is building on sand.

JH_Power | Posts: 47 | Location: Array

Bit of a tangent but does anyone know if Victron's Quattro units can be stacked for three phase at 24V, or do they effectively push you toward 48V at that point? I've only dealt with single phase in my van build so this is fairly new territory for me.

Also wondering what the actual use case is here — is this for a workshop setup like @MountainHermit mentioned, or something more unusual? Reason I ask is that if it's tools, most single-phase 240V kit can handle what you'd throw at it, so three phase feels like it's solving a problem that might not need solving at 24V bank voltage.

What's drawing three phase specifically?