Three-phase off-grid solar:
one inverter, or three?
Ten years ago, three-phase off grid meant three separate inverters, a wall of gear and a serious budget. Today a single three-phase hybrid does it in one cabinet, for less, and balances the phases better. There's one trade-off that decides which way a property goes — and one old rule that still applies no matter which box you buy.
From fifteen years of stand-alone buildsThe old way, and the new way
The old way — three inverters, one per phase. This is how Victron and Selectronic systems have done three-phase off grid for years, and still do: three single-phase inverter-chargers, one carrying each phase, locked together. A "15 kW three-phase system" is three 5 kW inverters. It's proven, it's serviceable, and its surge capacity for starting motors is enormous. It's also three of everything.
The new way — one three-phase hybrid. All-in-one inverters from Sigenergy, Sungrow, Deye and others put all three phases in one cabinet with the solar input and battery connection built in. Cheaper, tidier, and better at moving power between phases when the house pulls unevenly.
Every phase still has a limit
Here's the thing people miss about three-phase off grid, old or new: a single-phase appliance lives on one phase, and that phase has a ceiling. On the old three-inverter system the ceiling is one inverter — 5 kW per phase on that 15 kW example, so no single-phase load above 5 kW, full stop. The new hybrids are better because they can shift power across phases: on the same 15 kW unit, one phase might carry around 7 kW while the others idle. Better, not unlimited. A big single-phase load — a workshop welder, a ducted air conditioner on one phase — still wants a phase to itself, or moving to three phase, or a design that knows about it before it trips something.
Surge: where the two ways part company
Motors want a lot of current for a moment when they start — compressors, big air conditioners, welders, bore pumps, anything with a heavy spinning load. Off grid there is no network to lean on for that moment; the inverter carries it or the lights flicker and something trips. The old way, and Victron and Selectronic today, were built around exactly this: heavy transformers and surge ratings well above the continuous figure. Many of the new all-in-one hybrids weren't — Sigenergy and Sungrow among them, in our experience. They're superb at steady loads and phase balancing and thinner on the surge, because the grid was supposed to be there. Deye is the exception in that group: it's the hybrid we reach for when a one-cabinet system still has to start motors.
So the honest choice looks like this. If your property runs on efficient modern appliances and nothing with a hard motor start, an all-in-one hybrid is the sharper buy. If it runs a workshop, a big pump or a serious air conditioner, either you fit soft starters and choose gentle, efficient equipment to suit the hybrid — or you pay for Victron or Selectronic and start whatever you like.
“Either way you're going to spend the money. It just depends who you want to give it to — soft starts and efficient appliances, or Victron and Selectronic.”
— Mike Haydon, The Off Grid Shop
Victron quality in one three-phase box
The line between the two ways is blurring from Victron's side. The Multi HS19 Solar 15k puts full three-phase output, 15 kW continuous and four solar trackers in a single 19-inch rack unit on high-voltage batteries — one box, Victron monitoring and control. And three MultiPlus 20k units make a 60 kW three-phase system on the 48-volt platform for properties that want the surge headroom the old way is famous for. The right answer now has more than two options.
Three inverters vs one hybrid vs the new Victron options
| What matters | Three single-phase inverters (Victron, Selectronic) | One all-in-one hybrid (Sigenergy, Sungrow, Deye) | Victron HS19 / 3× MultiPlus 20k |
|---|---|---|---|
| Cabinets on the wall | Three, plus solar chargers | One | One rack unit / three units |
| Per-phase limit | One inverter's rating, hard | Higher on one phase by borrowing from the others | Per design |
| Surge for motor starts | Very high | Modest on most (Sigenergy, Sungrow) — plan soft starters; Deye is the hybrid built for it | High |
| Cost | Highest | Lowest | Between |
| Monitoring | VRM, GX, Node-RED | Maker's app | VRM, GX, Node-RED |
| Best for | Workshops, pumps, big motors, long service life | Efficient modern homes, budget-led builds | Large homes and farms wanting one Victron system |
Figures in the table are illustrative of the category, not one model's datasheet. Every design starts by listing the loads on each phase and every motor that starts — before an inverter is named.
Who three-phase off grid is for
Farms with three-phase pumps and cold rooms. Workshops and sheds with machinery. Large homes with ducted air conditioning and electric everything. Commercial sites too far from the network to justify the connection. And anyone whose property was three-phase on the grid and wants to leave it without rewiring the house. For most homes single phase is enough; three phase off grid is a decision the loads make, not the brochure.
Our design for one starts with the loads on each phase, a surge inventory — every motor, written down — the generator (a three-phase generator is the straightforward answer, sized with the same care), and then the inverter that fits: three Victrons, one hybrid, or the new one-box Victron.
Three-phase off grid, designed properly
Tell us about the property — what runs on which phase, every motor that starts, whether you're leaving the grid or building fresh. The design names the inverter and shows the working, including where soft starters earn their place and where they don't.
Prefer to talk it through? Call or text 0483 927 257 — Lismore HQ, local voices.
Three-phase off-grid questions, answered
Can you go off grid with three-phase power?
Yes, and it's far more doable and economical than it was. The old approach was three single-phase inverters locked together; today a single three-phase hybrid does it in one cabinet, and Victron now offers one-box three-phase on high-voltage batteries as well. Farms, workshops and large homes do it routinely.
Is three-phase off grid still three inverters?
Not necessarily. Victron and Selectronic systems still use three, one per phase, and that is the route with the biggest surge capacity. All-in-one three-phase hybrids from Sigenergy, Sungrow and Deye do it in one unit for less. The loads decide which suits the property.
Why can't I run a 7 kW appliance on my 15 kW three-phase system?
Because a single-phase appliance lives on one phase, and each phase has a ceiling. On three 5 kW inverters that ceiling is 5 kW. A modern hybrid can shift power between phases and might carry around 7 kW on one — better, not unlimited. Big single-phase loads get planned onto their own phase or moved to three phase.
Will an all-in-one hybrid start my welder, compressor or air conditioner off grid?
Sometimes, and it's the wrong thing to find out afterwards. Many hybrids have modest surge capacity because the grid was supposed to carry the start; Deye is the one-cabinet exception with real surge headroom. Soft starters and efficient appliances close the gap on the others; Victron and Selectronic carry it outright. Every design we do lists the motors first.
Victron or an all-in-one hybrid for three-phase off grid?
Efficient modern home with no hard motor starts and a budget to respect: the hybrid. Workshop, pumps, big air conditioning, or a property you expect to hand to your kids: Victron or Selectronic, or Victron's new one-box HS19. Either way the money gets spent — the design shows where.
Is a three-phase generator required?
For a three-phase off-grid system, a three-phase generator is the straightforward answer and it's sized with the same care as the inverter. Generator choice is part of the design, never an afterthought.