3-Phase Victron Powerhouse: 15kVA MultiPlus-II + 32kWh DIY Battery Setup with ESS-Green Mode

Really interesting to see 3-phase builds being discussed more — I've been lurking on similar threads trying to work out if something like this would ever make sense for a static caravan setup, which is obviously a very different scale!

A few questions for anyone who's gone down this route:

• With ESS Green Mode, how does the system handle overnight periods when solar input drops to nothing? Does the MultiPlus-II just seamlessly pull from the DIY battery bank, or are there switchover delays you'd notice?
• 32kWh is a serious amount of storage — what cell chemistry are people using for builds that size? I've seen folks on here go with Fogstar cells for smaller setups but I imagine at that scale you're looking at second-life EV packs or similar?
• Is 3-phase overkill unless you've got specific high-draw equipment? My caravan only needs single-phase but I'm curious whether the resilience benefits of 3-phase are worth the extra complexity and cost for a more permanent residential install.

I've been running a modest Victron SmartSolar + MultiPlus-II 48/3000 combo and it's been rock solid, so the brand confidence is definitely there for scaling up. The VRM portal monitoring alone makes it worth it in my view.

Would love to hear from anyone who's actually commissioned a build at this scale — particularly around battery BMS integration with Victron's DVCC. Did you use Cerbo GX for comms, and did it play nicely straight away or was there a lot of fiddling involved?

@Julie1991 a static caravan with 3-phase and 32kWh of DIY cells — you're basically building a Tesla Gigafactory with net curtains 😄

Jokes aside, it's not completely mad. The MultiPlus-II 3-phase stack is overkill unless you've got proper 3-phase loads

@Julie1991 honestly for a static caravan this is massive overkill, but I get the appeal of the tech. I run a much simpler Victron setup on mine — single phase MultiPlus-II 3000, ~10kWh of Fogstar Drift cells. Does everything I need.

3-phase only really makes sense if you've got 3-phase supply already or running big 3-phase motors/equipment. Most static caravan sites won't even have it available on the pitch.

What's your actual load list? That matters more than the fancy spec sheet stuff. 32kWh sounds impressive until you're paying for all those cells and the BMS headaches that come with DIY at that scale.

Not saying don't do it, just — what problem are you actually solving?

@Julie1991 Worth clarifying what your actual load profile looks like before committing to 3-phase. For a static caravan, single-phase MultiPlus-II is almost certainly sufficient unless you're running 3-phase motors or large HVAC. I've got a 48V cabin setup with Fogstar Drift cells and a single 5kVA MultiPlus-II that handles everything comfortably — heating, appliances, the lot.

The ESS Green Mode aspect is genuinely useful regardless of phase count though; if you're on a grid connection and want to maximise self-consumption from solar, that logic works well in VRM. What's your anticipated daily consumption in kWh? That figure will tell you far more about appropriate battery sizing than anything else. 32kWh is substantial even for full-time residential use.

@Julie1991 a static caravan doing 3-phase ESS is like fitting a Rolls-Royce engine into a garden shed — technically impressive, spiritually questionable, and your neighbours will absolutely hate you when the inverter fan kicks in at 2am.