Want 3-Phase Battery Backup? Here Are Your Options In 2024

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Want 3-Phase Battery Backup? Here Are Your Options In 2024

3 phase wiring diagram for full home backup from Sungrow

So you have a 3-phase supply to your place, and you’d like solar with battery backup?

Pickings were slim in 2018 when we last reviewed the situation. The good news is, since then, many new hybrid inverter models have entered the market, and full 3-phase backup is now possible without dropping crazy amounts of cash.

It might be worth brushing up on the terminology and some of the basic principles of energy storage if you’re unfamiliar with the jargon, but for this article, I’ll dive into 3-phase battery backup more specifically. It’s a long read because more phases means more complexity.

Three-phase loads are generally large appliances like;

You need a large and expensive home battery to meet these challenging loads without the grid.

Everything else in your house is single-phase, and in many cases, even large air conditioners can be single-phase units. Many EVs (including all BYDs) only have single-phase charging too.

So, if you just want the fridge, lights and WiFi to work in an outage, then you only need a single phase backed up. In fact, single-phase hybrids invariably have better surge capacity when running in off-grid mode, so if you have a rainwater pump to fill the kettle and flush the loo, then a 3 phase hybrid inverter might not be as capable.

Where you may need 3-phase backup from a battery is if you have a specific 3-phase load, like a fire pump, or if the wiring in your premises covers different floors. Segregating backup circuits can be difficult or impossible if 3 phases feed three different buildings, for instance.

If you already have a legacy 3-phase solar inverter, then integrating that will require careful design and equipment selection from your installer. Some hybrid inverters play well with others, but many will not; compatibility can be case by case, so get your expectations documented in the quote.

If money is no object and you want to treat the grid with contempt then you’ll use three Selectronic SpPros and a raft of other complimentary equipment. A bespoke design, class 6 battery from a specialist installer all means you’ll get no change from $100,000 by the time the shouting has died down. There’s a good chance your existing Fronius or ABB/Fimer solar inverters will be compatible though.

In a similar vein, soon there will be another option available for remote area jobs. A very well-respected Australian firm has developed the Xess One and has some promising specifications.

Charging an EV with a 3-phase Selectronic SpPro, PowerPlus batteries & Fronius solar inverter. This homeowner will power through Armageddon, no problem (unless it’s a nuclear winter).

People love the Tesla Powerwall. Customers and installers alike know they work really well. However, 3 phase is Tesla’s Achilles heel. In the US, there simply isn’t any demand for 3 phases (until you get into heavy industry), so Tesla doesn’t design for it. 110 V AC house wiring, fluid ounces, acres, feet and now NACS connectors for EV charging,… the freedumb eagles are just weird.

It’s not that you can’t have a Powerwall on a 3-phase supply; many do, and they enjoy lower bills. However when the grid fails, you have single-phase backup only.

Tesla simply doesn’t form a 3-phase 120° synchronised grid.

You can have three Powerwalls backing up three separate single-phase supplies during an outage, but they will not work together to run a synchronous 3-phase load, and they cannot charge from a 3-phase solar inverter (you’ll need 3 x single-phase solar inverters or microinverters). 

Available in a range of sizes up to 10kW, Fronius offer class leading surge capacity of 3.7kW per phase and modular battery capacity from stacks of BYD batteries. We have outlined many details previously, but it’s worth noting these machines work in parallel with your grid supply. They have a backup box arrangement to disconnect the mains supply, so there are some inherent features.

3 Phase Gen24 will need a “backup box” like this inside or near the switchboard. image credit Jae Taylor

Available internationally and offered here for a short time, the 3-phase SolarEdge solution was a false start. They do offer single-phase parallel hybrids, but until we get the Australian Standard for inverters, AS4777 rewritten, Solar Edge 3 phase isn’t an option.

The Enphase 5p battery and system controller only offer single-phase backup.

From up-and-coming to a solid contender, Sungrow has some persuasive technical reasons for 3-phase customers. They currently offer a range up to 10kW, but we understand a 15kW unit is coming soon. Sungrow has a really well-resolved stackable battery in 3.2kW increments. As a DC-coupled hybrid, they can black start if the battery runs flat overnight.

They can also run more solar capacity on the backup side. An extra solar inverter will help run appliances, help recharge the battery and help meet surge loads (if there’s sunshine, of course). If this is a Sungrow unit it’ll marry up in the monitoring platform, but other brands and models can be used successfully, with the Sungrow Hybrid shifting frequency to control generic inverters.

Sungrow is a series hybrid, so all the backup loads are connected through the inverter. This means when the grid fails you probably won’t notice the changeover. It’s not a true uninterruptible supply; they sometimes drop out, but generally, everything stays on.

Sungrow makes some solid gear.

There are some disadvantages to the series hybrid architecture Sungrow have chosen:

There is already a 15 to 29.9kW 3ph hybrid on offer from GoodWe. As a series hybrid, they share the same fundamental advantages & liabilities of the Sungrow solution and models. Important to note, though, is that while GoodWe offer a modular battery stack, they do not offer a warranty on expanding your battery at a later date.

It’s worth reading the fine print for any battery

Scratch the paint off a Redback unit, and you’ll find more GoodWe hardware, which isn’t a bad thing. The principal difference is the monitoring software, integration and support come from Brisbane. Not only does this mean you have a 10-year warranty, curiously with no other caveats applied, but you also have native integration for flexible export connections, which are increasingly becoming the norm for Australian networks.

Deye inverters are new to market in Australia, and while Deye (pronounced DAY, I’m told) is a large international outfit, choosing a unit with a NoArk sticker on it means you get support from an office in Australia.

These inverters are a crossover between a grid hybrid (high voltage, package engineered, class 4 or 5 BESS) and an “off-grid” inverter with a generator input connection. Some models even support 48-volt nominal batteries, which for a 3-phase all-in-one box is something nobody else offers.

If you’re on a budget and enjoy a punt, Solax, is still available, with gear that has never impressed me, but still being there to honour a warranty is actually a credit to them. Growatt, SAJ, Solis, all appear to have 3 phase hybrid products, but working out if they’re approved might be another matter. Searching the CEC list is made difficult when Solis & SAJ simply don’t appear as brands, so try Ginlong and Guangzhou Sanjing for better results.

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Anthony joined the SolarQuotes team in 2022. He’s a licensed electrician, builder, roofer and solar installer who for 14 years did jobs all over SA - residential, commercial, on-grid and off-grid. A true enthusiast with a skillset the typical solar installer might not have, his blogs are typically deep dives that draw on his decades of experience in the industry to educate and entertain. Read Anthony's full bio.

Hi Anthony, Thanks for the article. I have a 3-phase supply, but currently do not have any 3-phase loads (it use to run an old ducted system). What I am looking at though is adding to my existing solar capacity and installing a battery. Currently we have 4Kw of solar on Enphase 215w inverters (total 3.44Kw). I am in the Citipower area and understand it is a 5kw export limit and 10kw inverter limit per phase (battery counts towards inverter limit).

So if I want to add an extra 3-4kw of solar plus a Tesla Powerwall 2 should I put the solar on a separate phase and could this still feed into the Powerwall if it is on the original phase with the existing 4Kw of solar?

Hope this all makes sense.

Thanks for the article, Anthony. An interesting read.

“There is a 30-ish second delay in changeover when the grid fails. I call it a feature because it’s an unmissable analogue signal, a warning that you need to back off consumption and conserve energy”.

I’ve got the Gen24 and big BYD at home. It would seem to me that a simple display screen connected via cat6 cable would be a much better signal. A simple beep would do the trick. A simple hard-wired screen in a common area like a kitchen would also make it much easier for everyone in the house to understand the state of the system. Simple and hard-wired would pool poo all over the apps in general day to day use. Especially during an outage when your internet has dropped out and might not boot up perfectly.

The 30 second change over means I’m still running a few UPS units around the house. It’s a drop in the ocean compared to the cost of the whole system. It’s worth noting that this will cost you another several hundred on top of the rest IME.

Auto correct strikes again. Not sure why “pool poo” is better than “poo poo”. No Picnic bars in the pool please.

Hi Good write up. Only issue I had was with one footnote that was: “Just be aware that – if you want your solar panels to work in a blackout, you should use 3 x single-phase solar inverters or microinverters, not a 3-phase solar inverter” The Fronius Gen24 Plus Symo does..

I waited several years to get an inverter that does 3-phase, battery backup and runs fully during a grid outage. These conditions are met by the Fronius Gen24 Plus Symo. 3-phase to maximize export to the grid Battery backup electricity bill reduction Full or single point backup Panels provide power during outage

Fronius Gen24 Plus Symo 10Kw Trina Honey TSM-DE08M.08(II) 28x 385w 10.7 Kw BYD HVM 22.1 KwH Fronius Smart Meter 63A-3

I have the exact same system, 3-phase, Gen24 Plus Symo Hybrid, BYD batteries.

The panels work and charge the battery during a blackout / while disconnected from grid.

That footnote (1) as currently worded is not correct.

You can’t get good editors these days so I’ve reworded for clarity.

Thanks for the heads up.

I still don’t think it is quite right. Maybe: ‘…if you want your solar panels to work in a blackout, you should use 3 x single-phase solar inverters, microinverters or a three-phase hybrid inverter.’

Hi Johnno/Pat, did you get a pre made backup box for your Fronius Symo Gen24 plus or did your sparky put it together themselves? Eg

I’m hoping to get this inverter too so I can export more than 5kW to the grid. Peter

Hi Peter The sparky created it within the existing switchboard. Requires 5 DIN slots

Requires: Smart Meter Two contactors as documented in the Backup Guide and an additional contactor to provide power to the main relay.

Wiring between theses relays, the smart meter and the inverter.


I have implemented full backup so it all happens fairly simply. The network cable between the smart meter and the inverter has adequate cores to allow for the required comms for the backup circuit controls.

Thanks Pat. I’ll ask around for level 2 sparkies in Sydney who have done this before because it isn’t usual stuff for typical level 2 and I’d rather they don’t fumble about experimenting with my Install.

Why would a 3 phase house need 3 x single-phase solar inverters or microinverters rather than a single 3-phase solar inverter if they want their solar panels to work?

Per the info for a Sungrow Hybrid Inverter: The inverter works best with a battery but if there is a power outage, even without the battery, the inverter can power the emergency power supply directly from the solar (Provided the sun is producing enough power and the demand is not too high).

To me this reads as if the hybrid inverter would allow offgrid use of solar. Am I missing something since this appears to contradict what this article claims in Note 1?

Hi AB, Please help if you have time. I am getting an enphase system with 22 inverter and three 5P batteries from Plantation Homes.(with 52 c440 tier 1 and roof strengthing it is over $60 installed. There are some must have backup appliances such as drainage pumps and fridge aircon lights etc. Should every thing be on its own circuit or how do we arrange/plan it for the electrical meeting just before the contract. – tosayI’m confused is an understatement. Best Regards Matt

You might want to have a dive into how many watts those appliances draw to get a better picture. Something like your AC unit will chew through the battery pretty quickly. I’m yet to cause a problem with the Gen24 3 phase and 19.3kWh BYD at my place. We’ve had several outages and no problems so far. To be fair though, I’ve ditched all the 3p stuff, and our outages have only been a few hours at the most. The induction cooker had the option if I wanted to run more than one coil on boost mode.

I’m a builder, not a Sparks. AB will know way more than me.

Thanks for the info. I have a question. I planning having 8.2KW enphase system across three phases, possibly 2.7kw per phase, with intention of adding more solar at a later date, again with enphase microinverters. Is it possible to have a battery or batties connected to all phases, so they all batteries charge and drain equally?

In my off-grid situation, I have a petrol powered main firefighting pump and underground 40 mm fire mains run to cardinal points. For dousing embers while awaiting the fire front, the Grundfoss water supply pump has an integral VFD, so a few pushes on the “go faster” button cranks the supply pressure up for some serious squirty stuff. It stops when the hose nozzle is closed off – hydraulic remote control. With 46 kWh of batteries, there’s no need to start the big pump before the fire is about to arrive.

The machine tools, though several over 3/4 tonne, are all single phase. An awful lot can be done without the expense of 3 phase.

It’s only for faster charging of a compatible EV from the 30 kW of PV array about to go up, that 3 phase would be attractive. But 7 kW from a 32 A circuit will just about do for an old bloke. (The 24 yo Ford ute gave up the ghost last week, so I’ve just bought an MG4, but it’s hard to get an EV delivered, so desperate are they to retard uptake, it seems.)

Hi, I recently installed a 3 phase, 6.6kW SolarEdge PV system which has been performing well. Keeping my eye out on battery options, of which the SolarEdge was one. You mentioned it’s not an option here due to Australian Standards. Curious, what is the issue…. In layman terms….??

Our installer gave us a proposal for one, just prior to Xmas!

I’m waiting on a concise answer from SolarEdge themselves. It’s been a conflict with AS4777 that’s caused it. Will let you know.

Hi, I have 3x5kw single phase SolarEdge inverters (each on separate phase) with 17 kw of solar panels and 2 Tesla PW2 (each on seperate phase). Backups are provided for all circuits except for high power loads like induction, AC etc. However, I have been told that I can’t get the solar panels to work during a blackout unless there is a (DC coupled?) battery temporarily powering up the inverters, we can’t actually have the solar continue to charge the PW during outage…am I misinformed?

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Want 3-Phase Battery Backup? Here Are Your Options In 2024

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