Will it be illegal to install a single phase Powerwall 2 from Thursday?

Unless your local electricity network provides a local variation to a new Australian Standard that becomes mandatory on Thursday, it may be illegal to install a Powerwall 2 plus solar on a single phase.

[Note: Someone has contacted me to say that their interpretation of the standard is that a 5kW battery inverter and a 5kW solar inverter equates to a ‘rating limit’ of 5kW for the entire (IES) system. If that is correct then you would be able to AC couple a Powerwall 2 (or other battery) with a 5kW solar inverter on a single phase and not violate the new standard. I don’t agree with that interpretation. My interpretation is that the ‘rating limit’ is the sum of all the inverter ratings in the IES. I’m happy to be proved wrong on this.]

[Note 2: Someone else has suggested that a battery inverter that monitors the solar inverter’s output could be controlled in a way such that the total output of both inverters never exceeds 5kW. Technically this is feasible, although it would limit the ability of the whole system to provide self consumption. In practice I still think the ‘rating limit’ would be calculated as the sum of both inverter ratings, unless the manufacturer of the battery inverter could convince the DNSP otherwise.]

When is the s#!* gonna hit the fan?

This Thursday (30th March 2017) a new Australian Standard becomes mandatory. That standard is AS/NZS 4777.1:2016 or ‘Grid connection of energy systems via inverters, Part 1: Installation requirements‘ to its friends.

What is AS 4777.1?

It is the Australian Standard that mandates how solar and battery (and wind) inverters are connected to the grid. It was released on 30th September 2016 with a 6 month grace period. That grace period ends on 30 March 2017. So all solar and battery systems that are installed from this Thursday must comply.

Why Is This A Problem?

The second paragraph of Section 2.3 of AS/NZS 477.1:2016 states:

Unless specifically stated by the electricity distributor, the rating limit for a single-phase IES in an individual installation shall be equal to 5 kVA,

‘IES’ is defined in the standard as:

Inverter Energy System (IES) :  A system comprising one or more inverters together with one or more energy sources (which may include batteries for energy storage) and controls where the inverter(s) satisfies the requirements of AS/NZS 4777.2

‘Inverter’ is defined as

Inverter: A device that uses semiconductor devices to transfer power between a d.c. source(s) or load and an a.c. source(s) or load.

My interpretation of that clause is this:

Unless your local DNSP (Distribution Network Service Provider) publishes a local exception, the total amount of inverter capacity on a single phase system (when you add all the battery and solar inverter capacities together) cannot exceed 5kW1

For reference, this table shows you your local DNSP.

Why is this a problem?

Imagine you have a single phase home (as most Australians do) and you have a 5kW solar system on the roof. Now imagine that Elon Musk has charmed you into ordering one of his Powerwall 2 batteries.

Tesla has promised installations will begin in April, after the new standard comes into force.

But since Tesla decided to suddenly drop the DC version of the PW2 in Australia, you are forced to get the AC coupled version.

The AC coupled version has an inbuilt 5kW inverter, that converts the battery’s DC power to AC, so that it can be AC coupled.

So if you install this battery on your house you would have a 5kW battery inverter plus a 5kW solar inverter on a single phase and that appears to violate AS 4777.1 because the ‘rating limit’ of your IES is now 10kW.

As far as I can see, the only way you will be able to install a PW2 (or any other AC battery) together with 5kW of solar, legally on a single phase will be if your local DNSP creates a local exception.

Which DNSPs have announced local exceptions ?

I can’t find any formal announcement that any DNSP in Australia has a local exception that will allow battery inverters to be treated differently to solar inverters.

I’ve anecdotally heard that Energy Queensland will allow 5kW of Solar plus 5kW of battery inverter on a single phase – but I’ve seen nothing in writing.

I’ve anecdotally heard that different people at SA Power Networks have said they both will and will not allow 5kW of battery inverter2. So God only knows what SAPN’s position is.

Update: 3 commenters have kindly advised that Ausgrid, Essential Energy and ActewAGL are all approving up to 10kW per phase – it would be nice to see this in writing from these DNSPs

I’ve literally been through every DNSP website and used their internal search to find references to ‘4777’, ‘Battery’ and’Storage’ and scoured the results to see what their rules are – but they all simply say that AS4777 must be obeyed (if they say anything at all3 ).

I’m totally open to the fact that I may have missed a webpage, or not got an installer bulletin that has the answers for a particular DNSP. If anyone reading this can provide a link to something in writing from any DNSP please let me know and I’ll update this post right away.

How do you get around the new rules?

If your DNSP has not provided an exception to the 5kW limit and you have a single phase supply, a solar system and want a battery, then to comply with AS4777.1 as it stands right now, I believe you need a DC Coupled system that uses a Hybrid (AKA Multimode) Inverter that has a capacity of 5kW or less. A hybrid inverter only has one inverter for both the solar and the battery, so it will comply.

These diagrams I knocked up show the problem and solution quite clearly:

AC coupling requires 2 inverters

AC coupling requires 2 inverters. The maximum power of this ‘Inverter Energy System’ is the sum of both inverter ratings.

 DC coupling achieves the same outcome with one inverter

DC coupling

DC coupling with a hybrid inverter. The inverter is shared by the solar and battery.

And if you need a DC coupled system, that means you can’t have a Tesla Powerwall 2. Or an Enphase AC battery or any all-in-one unit that is AC coupled.

Batteries that can be DC coupled include LG Chem, Z-Cell, GCL, Ampetus and many others which you can find on our regularly updated battery comparison table.

Hopefully most of the DNSPs will provide exceptions before Thursday comes, but if they don’t Tesla may have to either reconsider its decision to drop the DC Powerwall or lobby each DNSP to make an exception – if they want to actually sell any single phase Powerwalls in Australia.


  1. 2 and 3 phase systems are a different kettle of fish, but to keep things simple this post will only look at the options for people on single phase
  2. But my experience of SAPN is that they are deeply culturally opposed to anything that helps small scale solar
  3. Essential Energy (DNSP for rural NSW) literally has no results for the term ‘battery’ across their entire site.
About Finn Peacock

I'm a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and founder of SolarQuotes.com.au. My last "real job" was working for the CSIRO in their renewable energy division.


  1. Who is “Energy Queensland”? There’s no DNSP with that name. Many areas in the Energex and Ergon DNSP areas are limited or banned from deploying any further embedded generation. We were lucky. Many people in our town are now banned from being grid connected.

  2. G’day Finn, I don’t believe that the DC version of the powerwall would help you much if you had an existing solar installation. As far as I understand the only single phase inverter that is compatible with the 400 volt Tesla battery is the Solaredge system ( as for the original powerwall) that requires the DC optimisation to be installed on the panels. Simply this means that retrofitting this inverter would cost as much as a new system. (no STCs to claim) The only exception would be if you had a small system and installed a 3 kW Solaredge inverter with there retro fit battery box. Not really an ideal answer

  3. Peter Seligman says:

    I’m OK with Tesla being out of it because I personally think that Lithium batteries are inappropriate for stationary applications. Once they wear out, you are left with a box of toxic junk to try and recycle. They contain up to 7 different elements including Cobalt.
    I would much prefer to see the Ultrabattery (basically lead) or Aquion if the company survives. Although their battery contains about 4 elements – said to be environmentally benign at least it got Bronze environmental certification.
    Happy to be corrected on anything if I’ve got this wrong.
    See https://seekingalpha.com/article/4027400-teslas-evolving-cobalt-nightmare

    • Erik Christiansen says:

      I can understand that distributors need to limit the load unbalance that each consumer/producer can impose, but isn’t it common for grid feed to be monitored and controlled? If the inverters grid feed only when the frequency is 50 Hz or less, and do not push the RMS voltage unduly high, then even a 10 kW capacity would only serve as support for a network sagging e.g. on a 43 deg afternoon. It would then be a godsend for the distributor – at no capital cost, and very low energy cost. Only coal would suffer.

      It’s the number of fires associated with Li batteries which make me run in the other direction. (Only on the Dreamliner there was nowhere to run.) Maybe LiPO4 batteries are less prone to spontaneous combustion, but I’ll still take lead-acid for now, and maybe Zinc-Bromine when the price improves. The low capacity of the big Aqion batteries is bad enough, but the dismal charge/discharge limit is the killer.

      • Peter Seligman says:

        How about the CSIRO based Ecoult Ultrabattery Erik? It has 3 – 10 times the cycle life of conventional lead acid, can withstand deep discharge and is 100% recyclable.
        Also has no flammable components


  4. Pat Comerford says:

    The vested interests of the power companies in this country have really got it in for battery storage. Following closely on another AS draft requirement to have batteries installed outside the property in a special enclosure and now this has introduced massive uncertainty into any prospective battery purchase. There has been very little awareness or discussion about this 5kw limit and the power companies are remaining mum on how they intend to proceed with approving new systems.

    • a.thomas says:

      Why do power companies have vested interests, but not battery companies?
      There are a raft of impending fire and safety regulations for all Lithium-ion batteries; not just home batteries. Although the risk of cell failure is low, that doesn’t mean any given battery risk is low.

      Late last year, Tesla promoted a fire test of their Powerpack, but that test actually took place before Feb 2016, and is the subject of this book:

      The results aren’t all that impressive. Flame escaped the enclosure, so would fail many indoor regulations and insurance requirements.

      The test subject was the Powerpack 1, and NMC or possibly LNO cells.
      To increase capacity for the Powerpack 2 and Powerwall 2, Tesla are using
      NCR21700 cells, which are the more flammable NCA. A pre-emptive strike,
      that is bait and switch.

      There are batteries, then there are Tesla batteries. It’s no accident that
      there are many caveats created by forcing an inappropriate cell onto the home and grid storage market, to be sold by appeal to capacity, at the expense of just about everything else.

      Don’t take my word for it, or dismiss it, but ask for proof of the supplier.
      Written performance figures, standards met, and what’s in the box.

      • Graham Alexander says:

        Although you have to admit that most house fires are caused by legal and legitimate crappy electrical imports from China.

        Lithium is a temporary solution until other technologies become economic and reliable.
        This is no reason to put restrictions on one of the most heavily regulated industries in Australia.

        Right now, the Polar ice caps are melting. This means we do not have the luxury of time to work out what the best way of reducing emissions. We need to cut emissions now, and right now, Battery storage is an extremely effective way of acheiving this.

      • To add some explanation. This article appeared Dec 19 2016
        The photos in that article can be found in the book, so is definitely the same test. The book dates the test prior to Feb 2016.
        The books offers technical details, confirming the battery is the ealier Powerpack 1 with low energy-density cells, and not the higher density cells of the Powerpack 2 and Powerwall 2.

        Many fire and safety regulations already exist for storage batteries, but the home battery market suddenly expanded, and ahead of widely anticipated regulations.
        Few would say that safety regulations for gas boilers, for example, are enforced to purposefully inhibit adoption.

  5. a.thomas says:

    A timely article, Finn.
    The AC Powerwall datasheet states that power output is “region-dependent”. My guess is that Tesla will control the power output to meet the allowed system total, or where exceptions may be granted.
    But, I would think to offer that, the battery must still meet the AS4777.1 standards, though there isn’t any indication that it does. One means of avoidance, may be to connect the battery to the AC household, but only when the grid is disconnected – a back-up only battery?

  6. Jasper Lee says:

    Well this is pretty pants

  7. Ausgrid has added this request when applying for connection…

    Ausgrid is currently trialling a streamlined process for the connection of micro embedded generation systems up to “10 kilo watts per phase in size.” In order to assess whether your submitted application form is able to be streamlined, Ausgrid will require some additional information and clarifications for assessment as outlined below.

  8. Finn,
    Is this a trade barrier in a different guise?

  9. G’day Finn,

    Not sure if you are aware, but ACTEW Distribution here in the ACT allow up to 10KW on a single phase. See Para. 6.5 at the following link.


    Not sure if this provision is still current. It is also unclear as to whether they would allow for a 5KW solar inverter plus a 5KW AC coupled battery inverter to coexist on a single phase or not.

    On another note: I note with some enthusiasm, that SOLAX are just about to release a number of 3-Phase hybrid inverters with the top one being 10KW. See datasheet here:


    However, I was keen to pair such an inverter with a DC coupled Tesla PW2 but given Tesla’s recent announcement, it would appear that I have been snookered once again 🙁 It is not clear why they dropped the DC option, but I can only imagine that they were trying to focus on capturing an already pre-installed market.

    Given the strength of this article, and the looming regulatory tank trap that is about to be put in place, then Tesla may need to reconsider its design options once again.

  10. So much for AS4777 being all about safety standards only. It should not be setting capacity limits because that is dependent on the DNSPs. Red tape over-reach if ever there was.

  11. Dudley Marks says:

    It seems no energy company or government or any other authority want to see household solar continuing. Let’s give them their wish and not feed back to the grid. They offer only peanuts in return. Would be interested to know how best to implement basically “off grid” with grid backup only. Size of installation is then your choice.

    • If you want batteries and use the grid as your back up just install a manual or automatic transfer switch. With such a switch you are either on the grid or totally off the grid.

      Then if your battery bank gets to low just have the tranfer switch to your utility to charge your battery. But be warned. Connection to the grid keeps setting more and more expensive. Called by different names It is a charge that you pay every month for the privilege of being hooked to the monopoly. Some places in the us is ashigh as $50 a month.

      • Dudley Marks says:

        Thanks John. I have had a 2kW solar installation since the “Fairy Ruddfather” first offered a subsidy and have enjoyed no power bills since the 60c FIT was introduced. I was going to upgrade after that FIT finished in December but my wife said she wanted a new roof first. I think it was fortunate this happened as LiFe batteries are still too expensive and in general too small.
        I have had experience with RV solar and have found lead acid batteries (normal sealed cranking batteries) last about 6 years if you ensure they never remain discharged for any length of time. I wonder if the latest nano-carbon lead acid ones might be comparable to LiFe . They seem to be offering good guarantees and prices. I am thinking of a sort of automotive system with Enphase panels driving a battery charger to the battery which is always connected to the inverter.
        The cartel will certainly increase connection charges and extend the period of high time of use especially when battery cars take off. I did some calculations and if i didn’t get my zeros wrong, 10% of Australia’s cars using 30kWh a day would consume most of the daily output of Erraring power station or several if confined to off peak. It’s an opportunity the Cartel will not miss

      • Hi John out here in Essential Energy area, we are not far from $ 50 / month access now, wont be long and we will be hitting that money mark, Regards Ray

  12. Colin Hoving says:

    Gee, that makes DC-coupled Z-Cell (fluid and not Lithium, so much reduced fire risk) an even better proposition!

  13. Batteries aside, does this mean you can’t have a solar system larger than 5kW at all?

    • Finn Admin says:

      On single phase you can’t have more than 5kW inverter. Most DNSPs will allow up to 33% more panels than inverter capacity. So 6.5kW of panels max.

      • I am assuming would not be the case with micro inverters

      • Sorry, that’s what I meant: your inverter can’t be more than 5kW. I assume they won’t force people who already have a system that is now deemed too large to take it off their roofs, so what counts?
        Does the system have to be installed and connected before 1 April? Or a contract signed? Or the SEG (Small Embedded Generator) approval granted by SA Power Networks (or other DNSP)?

        Also, can you install a battery in such a way that it can’t export to the grid but only used for own consumption? And if so, would that then not count towards the kW?

        (yes, I realise a fool can ask more questions than 1,000 wise people can answer)

        • Australian Standards are not retroactive – so they are not going to force old systems to comply unless the old system is modified or upgraded after the new standard comes into force.

          Any systems installed after 30 March 2017 have to comply with the relevant Australian Standards in force at the time – including this one.

          Yes – you can export limit many inverters – but the standard does not appear to allow for this as a way around the 5kW limit.

  14. Graham Alexander says:

    100 years ago, when they invented cars, the roads simply had to be upgraded from cobblestones to cope.
    50 years ago, we sent 3 men to the moon and got them back alive.

    There is only one reason that the grid can’t (or wont) be upgraded, and that’s to protect the horse and car market.

    It begs the question: Who exactly does the government represent?

  15. We wanted to upgrade our 5.75 kW system by adding additional panels to take it to 7.99 kW. To remain connected to the grid Ergon required us to upgrade our power supply from single to three phase. The cost of do that was as follows: Digital Meter replacement and installation 1,200.00, Trenching to lay the conduit and three phase cable 500,00, electrical contractor to make the connection at the Pillar and Meter Box 900,00 total $2,600 plus the cost of the solar upgrade $3,500 total $6,100. What is interesting to note that with three phase Ergon will allow 10 kW per phase but not in single phase.

  16. I’m pretty new to this, but presumably if you do not yet have solar you can get the PW2 directly connected to solar panels (DC) and batteries (DC) and then use its inverter to output AC.
    Therefore one 5kW inverter = o.k.

    If above true, would also be good for replacing old inverters e.g. early adopters who have 2-3kW systems. Would remove old inverter and re-use panels and add more panels to get up to 5kW (+33%).

    • Sorry Ash, you can’t plug solar panels into the PW2 and share the inverter. It is a battery inverter only. hence the need for a 2nd solar inverter.

      Ii would put money on the Powerwall 3 having that ability though. I’m guessing by then Tesla will be able to sell you a single box that contains a battery and hybrid inverter and the Tesla solar panels plug straight in.

  17. Bruce Long says:

    Hello Finn, we have just ordered a system last week which is due to be installed later in April, I contacted the company supplying the system with a Solar Edge SE6000 6kW inverter and a Tesla Powerwall 2 which according to your article would be a problem.

    The suppliers response was that it was not a problem as they could ” We can export block the battery or the solar pv system which we have already extensively discussed with Tesla and it’s definitely doable.

    No issues moving forward so please be rest assured.”

    What are your thoughts?

    Any advise appreciated

    • As far as I am aware export limiting does not solve the problem of having 2 seperate inverters in the system which add up to more than 5kW total.

      There is a specific definition in the standard: “Export limit: Limit on the export of electricity to the grid from an inverter energy system.” The clause I quoted specifically does not use this term it says ‘Rating Limit’ – so I’d be very confident that Export limiting is not allowed as a way to get under the 5kW total inverter(s) rating. And there are good reasons for this to do with grid stability.

      If you have a 3 phase inverter you will be OK if it can actively balance the phases as per the standard. If single phase – I think you will have a problem unless you have specific permission from your DNSP.

      I guess you could monitor the output from the solar inverter and control the battery inverter in such a way that the total output of both inverters was never more than 5kW. But that would limit your ability to use battery and solar power for self consumption. I also don’t believe that workaround would satisfy AS4777.1.

      Ask them to show you the clause in AS4777.1:2016 that allows their proposed workaround, or the DNSP advice that allows this, if you want to be sure.

      Was it Natural Solar by any chance?

      • Bruce Long says:

        Yes it was Natural Solar good guess!

        Is there something I should know?

      • Bruce Long says:

        We have 3 phase but they are installing a single phase inverter

        • I can’t see how they can make this conform with a single phase inverter, unless they have permission from the DNSP to have more than 5kW of inverters in a single IES.

          As it stands they would have to derate the SolarEdge 6kW inverter to 5kW. That is very different from export limiting the 6kW inverter.

          Again – your DNSP has the power to say you can install more than 5kW of inverters on a single phase. I’d be asking to see that permission personally.

          • Bruce Long says:

            I received a copy of the solar pre-approval from Citipower as follows:

            Citipower and Powercor Solar Pre-Approval Assessment
            Solar Pre-Approval Assessment Outcome: As Applied For
            Approved Capacity: 6.5 kW

            Approved Capacity Per Phase
            Phase 1: 2.2 kW
            Phase 2: 2.2 kW
            Phase 3: 2.1 kW
            Proposed Generator Installation Details:
            Inverter Power Rating: 6.5 kW

            Proposed Inverter Capacity per phase
            Phase 1: 2.2 kW
            Phase 2 2.2 kW
            Phase 3: 2.1 kW

            Given that they are installing a single phase Solar Edge SE6000 6kW inverter and the Powerwall both on the same phase does this mean they would have to derate the inverter rather than export limiting it?

          • II believe the SE6000 is a single phase inverter. It looks to me like Powercor have said you can’t have more than 2.2kW on a single phase. So I can’t see how your approval allows the system you describe.

            I would either:

            a) get a 3 phase inverter – and check that your powerwall can integrate into it, the 3 phase inverter will spread the load over the 3 phases, and is the best solution from an engineering point of view.

            b) ask Powercor for explicit approval for a the single phase inverter

    • Guy Stewart says:

      It is up to the installer to comply with the standards, not the consumer. If your installer says no worries, it is on them to make sure the work is up to scratch.

      I would be on the lookout for contract conditions that place penalties on you (such as forfeiting a part of the deposit if rejected or costs associated with failed applications).

      Good luck with the new system, I hope it goes smoothly.

  18. Scott Elford says:

    Hi Finn,
    Thanks for the above info, I do remember reading about this change when it first came out. It had slipped my mind maybe or that might be why I started to plan an off grid system. I have a 5kw grid tie installed and also a small off grid system which I’m slowly increasing it capacity. Batteries are my issue at the moment ( getting hold of a bigger bank on limited budget). The off grid section has a change over switch for when it’s required, I have installed a new swbd for the off grid to run and wired new circuits to it.

    I believe that in the future this is going to be the way to go, mostly or totally off grid. But the network may still require people to be connected to the grid. At the moment you can go of grid in some area’s with out an problem.

    Over here in the WA ( wait awhile ) Synergy are advertising a new smart system is being release to control and sell our power, no real info yet. Have you seen anything on this? Maybe it is something like Reposit power system or style. Not sure how this will factor in with the new rules coming into play..

    Maybe there is going to be some concessions,.. Time will tell.

    Thanks for your great info & keep it up.


  19. Scott Elford says:

    Who is running the show anyways???? LOL

  20. Essential energy area the quartly access fee is really close to $ 150 / Qtr, Regards Ray

  21. Richard Gault says:

    My quarterly Bill shows 96c as the average cost of electricity to me each day.
    Theres an additional Ridiculous daily access fee of $1.39 so I am paying way more for access than the power I actually use. Is there someone that I can actually get to review my Bill.

    Do you have a list of New Retailers in the South East queensland Region????

  22. Graham Alexander says:

    I have emailed off to SA Power Networks in SA for clarification. I’m expecting them to copy and paste from the standard in about 3 weeks. That’s what normally happens.
    I think it may fall to Tesla to put some public pressure on the DNSP’s to publish their interpretation or exception.
    that’s also what normally happens.

  23. I have 6.5kW of sunpower panels feeding a fronius 5kW inverter(not hybrid as I have polyphase not 3phase)
    For those of us that only want to store for our own consumption, I’m not interested in reposit or any other scheme, is there no technology that would limit the feed in to 5kW if I installed a powerwall 2 or equivalent, If not why not?
    Can I use my polyphase connection to my advantage, I do live on acreage and my meter box is 30m from the suppliers pole, apparently why I have polyphase?
    I am not an expert, just an interested consumer, so be nice!

    • Absolutely. Many inverters can export limit to a desired max kW. But the Australian Standard talks about a ‘Rating Limit’ in regards to the 5kW limit, and defines ‘Export Limit’ differently. So having an Export Limited inverter does not get round the clause if the inverter rating is higher than the export limit. There are reasons for this – which I may go into in a future blog post.

      The only way to have more than 5kW of inverters on a single phase is with specific permission from your DNSP.

    • Ronald Brakels says:

      Hello Patrick. I’ll try to be nice. It is definitely possible to export limit solar or solar + batteries to 5 kilowatts, but that won’t meet the requirements, so I’m afraid it won’t help. The rules are very picky. (And very stupid.)

      If, by polyphase, you mean you have three phase power, then you could put a 5 kilowatt solar inverter on one phase and a 5 kilowatt battery inverter, such as the one in an AC Powerwall 2 on another phase. But, as you are on acreage, I suspect you mean you have Single-Wire Earth Return (SWER) transmission in your area which some people call 2 phase. (I don’t like that term because I’m picky.) So you are very likely to have single phase power and so be limited to 5 kilowatts of inverter in total.

  24. Hi guys Im here in Essential Energy area, I have installed lots of solar systems on single phase, and have been in excess of the rated 5 kilowatts, If you follow their criteria, and meet all the expectations, then they will approve your system. I have also had systems, that would definitely NOT be complient, especially with Voltage Rise Calculations, I do all the calcs as required, show all the percentages, and then I actually include on my line drawing, and in the special notes area of the on line form, that I will be export limiting the system, to either NIL export, or 2 kilowatts export MAXIMUM, then the application comes back approved. Regards Ray

  25. I do recall that whne I installed my solar panels, the installer said that up to 10KW, I did not need any special authorization. I am with Ausgrid in Sydney.

  26. Hi Finn,

    I’m in Victoria and currently have a 3kW solar system. I recently got some quotes to put in additional solar and I was quoted a fairly competitive price for a new 5 kW system. Everything went through to just the day before the install before I was told we got knocked back by the power distributor. It turns out having single phase means we are limited to up to a 5 kW generation system, so now it means I have to make adjustments to my current system and only top up another 2 kW of panels for a maximum of 5 kW. I didn’t go ahead with it because with the requote now means it’s no longer that attractive a price.

    To go more, I have to go 3 phase. Is that worth doing at all so that I can expand?

    • Ronald Brakels says:

      Hello Fauzi, Ronald here. The cost of upgrading to 3 phase power depends a lot on your location. It may cost a couple thousand dollars or in a rural area it may cost tens of thousands or dollars or more. I’m afraid I don’t know what it typically costs in Victoria. Whether or not you’d find it personally worthwhile to upgrade I couldn’t say, but it is possible you may be able to spend the money on making energy efficiency improvements and perhaps come out ahead that way. Installing solar hot water would be another option.

  27. Finn,
    It is now 5 April.
    Presumably there is now an actual response to the “(post 30 March) it may be illegal to install a Powerwall 2 plus solar on a single phase” conjecture?

    Does anybody have any factual information out there?

    Also, on the fairly widely publicised issue of a forthcoming Australian Standard for large lithium batteries (as in PV solar battery systems) being mandated to be (expensively) stored outside in a fireproof enclosure: has anybody heard of any developments, please?

  28. Finn,

    I have a 5Kw solar array connected to the grid, but would like to put a parallel system of at least 5Kw solar and a powerwall 2 not connected to the grid. Does this standard apply to the new system? Or affect the old?

    • Ronald Brakels says:

      Hello Ian, Ronald here. If the new 5 kilowatts of solar and the Powerwall 2 are not connected to the grid in any way then they have no power over you.

      The new standard will apply to the old system as it will still be connected to the grid. So if you have single phase power you wouldn’t be able to add a Powerwall 2 to the grid unless your local electricity network operator says that is permitted. (And hopefully they will say that’s okay.)

  29. For a start…
    In Vic, Ausnet won’t allow you to install a 5Kw system ( on single phase ).
    & they don’t go by your inverter size at all, but rather the quantity size of
    ( kW ) of your array of panels!!! Thus, they will only allow a 4.6 Kw system to be installed!!! ( you can pay $250 to Ausnet & ask for permission for 5-10Kw, but they only allowed myself a 4.94Kw system of Micro Inverters.
    ( I don’t recall those T.V. commercial ( 5KW ) flogging solar companies mentioning anything about that? Do you? )
    So, How does this equate to this new legislation ( being that Ausnet will only allow 4.6 Kw of panels ) for a Powerball 2 or other???
    Now with my 19 panels ( 4.94 Kw ) of Enphase Microinverters, can I install 1/2 a dozen (6) Enphase 1.2 Kw Batteries on single phase or not????

  30. RIchard says:

    We have 3 phase to our meter box. Does that mean I can connect a Powerwall 2?

    • Ronald Brakels says:

      Hello Richard. My understanding is the AC Powerwall 2, which appears to be the only Powerwall 2 that will be available in Australia at the moment, can only be connected to one phase of a house with 3 phase power. This means it will only be able to supply electricity to appliances on that phase and at most will only be able to provide one-third of the energy consumption of 3 phase appliances, such as many large ducted air conditioners. It will also only be able to charge with electricity from that phase. If you are not permitted to install rooftop solar on the same phase as the Powerwall 2 then you will only be able to charge it with grid electricity, which is usually far from optimal.

      • RIchard says:

        Thanks Ronald, very interesting. Seems like a no-win situation…

        • Hi Gents,
          I have 3 phase power to my house. I have ordered a PV system of 18 x 330W LG panels with Enphase micro inverters and a Powerwall2. I am now very concerned that I will be using the Powerwall to run only one third of my house of a night and using the grid for the other two phases. Is this correct and is there any way around it if so?

          I gather the backup function would only power one third of the house in a blackout as well? Any way around this?

          Seems like having three phase is a major problem with the power wall.

          Is being able to have 10kW on each phase (Ausgrid) a way around this somehow?

          Confused and clueless……

          • Ronald Brakels says:

            Hello Chris. I’m afraid that is correct. As far as I am aware the AC Powerwall 2 can only be connected to one phase. You can put the Powerwall 2 on which ever phase is likely to be used the most at night, but obviously that’s not an ideal solution. When providing back up power it would only be able to supply power to the phase it is connected to.

            Being able to connect 10 kilowatts to a phase won’t get around the problem that it can only be attached to one phase, but it would allow both the Powerwall 2 and the solar inverter to be placed on the same phase.

            There may be ways to work around this, but I don’t know what they are at the moment and they would entail additional expense. All I can suggest is going for a different battery that can be DC coupled and using a multimode (hybrid) 3 phase inverter or simply putting off the Powerwall 2 purchase and waiting to see if Tesla will get around to providing a 3 phase solution.

          • During the installation you could put most of your house circuits onto the same phase that has the solar inverter and the Powerwall. Leaving only the things that actually need the 3-phase power. If you have some high current draw items like a solar hot water booster or an oven or cooktop, they could be left on the other phases to spread the load around. Particularly when their use can be avoided if and when the grid is down and you are running off the Powerwall as a backup. Your sparky/installer should be able to do all that.

  31. Why use a Tesla system when this is available, don`t get sucked in by all the hype, this system works and is used by the railways , why, more reliable, more friendly, wont burn your house down, easy recycle, a bit more to set up but you only need to do it once properly.


    Equivalent to a 2000amp hour 24v lead acid or gel battery pack, as a lead acid or gel pack has only 20 % usable without shortening life
    Nickel iron batteries are not effected by deep discharge they can be 100 % discharged every cycle without adverse effects on their life span unlike gel or lead acid that if discharged below 80% their life will be dramatically shortened
    Being able to be 100% discharged means that the size of your battery bank can be reduced by as much as 75%!
    They are not effected by over charging
    They are environmentally friendly
    They are not effected by temperature
    Can be rapid charged with no effect on life
    They thrive on work unlike lead acid in either wet or gel form
    When they finally start to loose capacity its a simple job of changing electrolyte and they are back to work for another 30 years
    We encourage some research on these batteries yes the initial outlay is a little higher but they will outlast solar panels and every other component in a off grid system
    This was taken from a web site and explains why we need nickel Iron not lithium iron. They were invented by Edison 100+ years ago so they are nothing new.
    I Have a 108KW battery system on or off grid with 15KW solar. 1.4Kw Wind generator, an 8KW back up generator and a Tesla generator 1kw per hour. I can go off grid whenever i please. it has cost me $30K and I currently have a 2.5K credit with my Provider. It took me 6 years to do it but I am Free of the Big Boys . I AM IN CONTROL. They still pay me 66 cents for original 2.2 KW solar. So their are alternatives just do you research and be patient and go for it.

  32. Patrick says:

    A Gold Coast based solar installation company that advertises on Facebook are claiming that Energex here in Queensland are allowing 10kW inverters on single phase homes.
    If it’s on the internet it must be true, right?
    So that means that those of us that have 5kW inverters on single phase homes are also able to install a powerwall 2, right?
    It is odd that this company is not selling the powerwall 2, they are selling LG and the hybrid inverter appears to be 5kW, but they are selling 7.54kW of panels as part of the package!
    Help, I’m confused, surely there’s not a whole lot of miss information getting around on Facebook!!

  33. Tim Efthymiou says:

    Hi Finn, great article. NOW LETS GET TO THE 3 PHASE SENARIO.
    I have 3 phase at my place. I have a 5kw solar system which includes – solar cells, inverter, (and recently connected to this system) a powerwall 1 through solar edge battery inverter.
    That’s the original system and works very well indeed.
    I wanted to expand my system (due to electricity hungry shithead kids of mine and the misus, using the dryer when it’s a nice sunny day outside!!!).
    So, I have added another 5.4 k.w solar panels connected to a hybrid inverter in readiness for the powerwall 2.
    My question is, I have a smart meter from Ausgrid which have been told that, it doesn’t matter which phase the battery/solar system(s) is connected to, the smart meter will switch around to distribute load and take into account the solar energy produced. is this corrected??? obviously you don’t want all your electricity needs put on one phase (load) and you want to distribute electricity needs across all three phases. basically I don’t want to have this great big 10.4 kw system with pw1 and pw2 and not be able to take full advantage. Any ideas of thoughts. The way I see it the most logical connection is to connect the largest battery/solar (pw2) to the highest load phase and the pw1 system to the next medium load phase and the least load phase will not have anything (solar/battery) connected to it. Again any ideas or advise???

    • Peter T says:

      G’day Tim,

      I know you have asked this question of Finn here, but I thought I would just apprise you of the new SOLAX 3 phase hybrid inverters that are due out in Australia in the next month or so. See here:


      I am not sure how well these inverters operate by comparison to others or what price point they will sell at initially, but the advantage I see with this higher spec’ed inverter (and perhaps other hybrids that might yet enter the market into the future) is that you could simplify your design and implementation, thereby interconnecting your batteries into one DC bank and using the higher spec’ed inverter to load share across all phases.

      Hope this helps mate



      PS Not sure if the new AC Coupled PW2 can be reconfigured to be DC coupled instead. If not, then I believe this is a major faux pas on Tesla’s part, and as such, they should remedy the situation to provide end users maximum flexibility.

    • Ronald Brakels says:

      Hello Tim, Ronald here.

      The smart meter won’t redistribute loads, but it will only charge you for your net grid electricity use. For example, if you are importing 2 kilowatts of grid electricity on one phase while exporting 2 kilowatts of solar electricity on another phase, as far as the meter is concerned, at that time you are not using any grid electricity.

      Putting the largest battery on the phase that will have the heaviest loads in the evening and the smaller battery on the phase with the second heaviest evening or night time loads is definitely sounds like a good plan to me.

  34. Ken Linder says:

    I just got knocked back as having a SWER (so 5KW only), except that the three electricians who were out here over the last 3 years all said is was standard single phase, which is why the last one (from the solar company) quoted us for a 10Kw system in the first place.

    So either the electrician was blind (or incompetent) or SA Power Networks has it wrong. This house used to be the local general store with a lot of freezers and fridges running 24/7 (and a big old air-con). I don’t know if the store COULD have run everything they used on a SWER ,

    If they are right (SWER) it makes no sense to me at all that the utilities would be subverting the entire purpose of an export limited inverter.

    The goal of the export limited inverter is to be kind to the grid while letting customers (who are small producers) generate more than the amount the grid can safely handle. The goal is to let people generate 10Kwh on a system that cannot export more than 5Kwh.

    Such an inverter is supposed to isolate the grid from anything over the limit. This is *ideal* for the companies that use the grid. This is accomplished BETTER using an export limited inverter, because nothing can ever happen on the customers side of the wires which will give the grid more power than it can handle. It is safer – yet they don’t seem to want it.

    However your experiences will vary according to who runs the grid (and what phase of the moon it is).

    *** THE POOP IN SA **

    According to an email from SA power Network, these are the rules for exceeding your max generation by using an export limited inverter :
    ————— quote ————-
    1.Under SA Power Networks terms and conditions for connection of SEG systems to our distribution network it is not permissible to connect a SEG system with a peak capacity rating greater than 5.0kW to a 19kV SWER distribution networks unless an approved export limiting inverter is used*.

    *Export limited SWER inverter connection applications will be assessed as: the total inverter capacity connected to the SWER network at a specific connection point and includes the size of the inverter connected to any proposed energy storage system (ESS), unless the inverter is of a non-export or stand-alone nature. The export limit of 5kW per connection on our SWER system and requirement for compliance to AS4777 (current version) still applies

    !!!! (HERE IT IS ) !!!!

    When a customer proposes to use an export limited inverter connection to achieve compliance to above they must demonstrate to SA Power Networks’ satisfaction the effectiveness of the export limit including:

    1. Documentation of export limitation device including installation details – precise limitation limits must be confirmed and documented by the owner and solar provider.

    2. Export limitation device shown to operate as specified, (via commissioning witnessing for each manufacturer and model type) – suitable testing equipment used, data in a suitable format supplied and testing to take place when output of source is at least 110% of claim of export limitation – i.e. export cut-off should be visible in test.

    3. Export limitation device to be sealed so as to prevent tampering with settings. Any tampering must be self-evident.

    4. The ability to import (or charge an ESS) must still be within SA Power Networks SWER load limits (10kW on single phase systems).

    ————— end quote ———

  35. I have been researching and looking to go as big a system as my roof will allow. I just found out from Actew that my maximum size is now 5kW. That won’t even halve my power bill. I asked if I can have a capped export inverter then use another battery system/inverter to run the home and the answer was no. It is based on the total of the inverters connected, regardless how they are connected. So, a 5kW system on the house can not be hooked up to a PW2 because of the inverter built in to it, putting the system over the cap. What a complete farce this decision is. By limiting sizes of systems, they are keeping their stranglehold on customers who have to rely on the grid for most of their power, instead of using batteries to minimise the peak. Totally off-grid is becoming the only real option for me now as a plain Jane 5kW with battery is not going to have a very good payback at all, let alone impact on my huge bills.
    How is this helping us move towards a clean energy future, when discouraging solar through dumb regulations like this are happening?

    • Peter T says:

      G’day Marko. I provided a link to ACTEW’s regulations document further up the page here, but that document has now been superseded, and so for your immediate reference, please refer to the table and accompanying dialogue on page 8 of the document at this link:


      I am not sure who has been advising you, but it seems they are full of shit. As the Reg. states, you can have up to 10KW per phase on either a single or three phase connected house – even in scenarios where more than one inverter exists on any single phase. Given the sustained output power of the PW2 is 5KW, then you can easily install the PW2 providing the other single phase inverter does not exceed the 5Kw limit.

      Also, and I suspect most may not know this, but the ACT Government currently has the NextGen program running (expires 1st Sep 2017), which provides a battery rebate of $825 per KW of Sustained Output Power (SOP). The rebate limit per household is 32KW of SOP. Therefore, the PW2, as just one example, would deliver a $4,125 rebate per PW2 to anyone who installed it (i.e. PW2 has a SOP of 5KW x $825/KW = $4,125). I am reasonably sure even Ronald B. would conclude and advise accordingly, that solar batteries are now a viable financially smart option under such circumstances.

      Finally, I have it on good authority that Tesla is working towards a 3 phase implementation, of sorts. Given that I am 3 phase connected, I wait with bated breath for the detailed technical solution.

      I hope this helps mate. Cheers Peter


  1. […] Standard for ‘Grid Connection of Energy Systems Via Inverters’ and, according to this article from Finn Peacock at Solar Quotes, it may well make it illegal to install a Powerwall2 on most houses with solar in Australia. This […]

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