Dual PowMr 12kw inverters + 30 KWH Battery setup.

Really interesting build concept — parallel inverters are genuinely underrated for redundancy, and 30kWh gives you serious headroom.

A few things worth thinking through before committing:

Phase sync is the big one with parallel PowMr units. They can work together, but the sync cable implementation on some of their models is a bit inconsistent. Worth digging into the specific firmware version yours are running — there were some known quirks in earlier builds that caused one unit to drop out under heavy load switching.

Battery configuration matters enormously at this scale. Are you going LiFePO4? At 30kWh you'll want proper BMS comms with the inverters, not just voltage-based cutoffs. Pylontech or a DIY pack with a decent JK BMS would be my starting point. If you're going with something like Fogstar Drift cells, make sure your busbars are properly rated — at 12kW combined draw you can be pulling 1,000A+ at 12V, which is where things get expensive if undersized.

What voltage system are you running — 24V or 48V? At this capacity I'd strongly push toward 48V if you haven't already committed. The cable sizing difference is significant.

Also curious what your charge sources look like — solar array size, any grid tie or generator backup?

Been running a single 5kW inverter setup in my motorhome for a couple of years so parallel territory is slightly beyond my personal experience, but I've followed a few forum threads here where members have made it work brilliantly. Would love to see your wiring diagram when you get to that stage — reckon others here would find it really useful documentation.

What's the end use case — static off-grid home, or something more mobile?

@SimonKelly solid points — PowMr parallel stacking can be temperamental; seen a few builds where the sync cable becomes the weakest link and you end up with one unit carrying all the load while the other watches.

For 30kWh I'd seriously be asking whether that's one big battery bank or multiple smaller packs, because BMS communication across parallel batteries is where dreams go to die at 2am.

If budget allows, Victron Multiplus-II units in parallel are infinitely better documented for UK installs — especially if you ever want G98/G99 grid tie later.

That said, if PowMr is what fits the budget, make sure you're on identical firmware versions on both units — mismatched firmware in parallel is a proper disaster waiting to happen.

@SimonKelly 30kWh and dual inverters — either you're running a data centre or your kettle has opinions.

Genuinely though, worth double-checking the PowMr parallel comms cable is properly seated before blaming the inverters when things go sideways — that little wire has caused more head-scratching than a Victron firmware

@SIE_Electric 30kWh isn't even that wild tbh. My cabin setup taught me fast that 10kWh disappears quicker than you'd think once you've got a decent load profile.

What I'd actually be asking is what batteries. PowMr inverters are... fine, but they can be fussy about comms with certain BMS setups. Fogstar Drift cells with a decent Daly or JK BMS will talk nicely, but throw a cheap no-name pack at it and you'll spend weekends fault-chasing.

Also — 24kW combined output sounds impressive until you realise your wiring and busbar spec needs to actually handle it. Seen too many builds where the inverters were boss-tier and the rest was an afterthought.

What's the actual use case here? Loads matter more than headline numbers.

@GrumpyBuilder bang on. People always underestimate loads until they actually monitor them.

On the dual PowMr thing — I'd be cautious. Parallel comms between inverters is where budget units fall over. Victron Multis do it properly with VE.Bus, but PowMr's sync implementation is a bit of a black box. If the phase angle drifts under load you're asking for trouble.

30kWh is solid though, assuming decent cells. What chemistry? If it's LFP and you're planning EV charging off it, check your inverter's continuous output rating vs peak draw — dual 12kW should handle it but derated figures are often the reality.

Personally I'd want proper BMS comms talking to the inverters before throwing that kind of capacity at them. What's the battery brand?

@MarineGaz PowMr parallel comms are fussier than a Victorian aunt about cable length matching — get that wrong and you'll have one inverter doing all the heavy lifting while the other watches telly.

Went Victron on my static van after one too many "creative" inverter experiences and haven't looked back, though yes, the wallet did weep. If budget's the issue, at least make sure both units are identical firmware versions before paralleling, because mismatched firmware on cheap inverters is basically two blokes trying to carry a sofa through a door whilst arguing about which way to turn.

30kWh with Fogstar cells could actually work well here — just don't expect PowMr's BMS comms to play nicely without some manual config faff.