Outsmarting Solar Connection Limits With Semi-Off-Grid Appliances

Maximizing solar production without exceeding limits

Network-imposed solar system size limits can sometimes squash our dreams of tiny bills, but Glen from Perth has discovered a game-changing solution.

Bucking traditional constraints, he’s unlocked a brilliant strategy many haven’t considered.

Step into a future where living large doesn’t mean large bills: as we dive deep into the untapped potential of semi-off-grid appliances.

Glen’s Solution: Going Semi-Off-Grid with Hybrid Solar Appliances

Glen, a retired engineer from Perth, installed rooftop solar in 2010. Western Power permitted only a 5kW inverter at that time, distributed over three phases. To harmonise with the grid, Glen split the 5kW between a 2.0 kW inverter and a 2.8 kW inverter on separate phases.

But rules change. Now, Western Power allows just 3kVA per phase for single-phase solar inverters on a 3-phase setup. Without any updates, Glen is nearing his inverter capacity on two of those phases.

Western Power export limits 2022

Western Power maximum basic EG (embedded generator) system capacity and export limits. Image: Western Power

Batteries First, But Glen Soon Realised: More Solar was the Answer

In 2021, Glen added a Powerwall 2 battery. Just five months later, he installed another. This meant a 2.8 kW inverter with a 13.5 kWh Powerwall on one phase and a 2 kW inverter with a 13.5 kWh Powerwall on another. Seems excessive? While Glen stands by his choice, one could argue he missed the mark.

With limited solar on each phase, an extra battery didn’t up his solar intake. The numbers for a second battery just didn’t add up. Glen’s flat rate tariff, smaller rooftop system, and daytime power usage as a retiree pointed to one solution: more solar panels.

Aware of this and nearing his limit on two phases due to Western Power’s rules, Glen faced a choice. He could add a 3kW system to the third phase or overhaul his existing setup for a new 3-phase inverter and solar arrays, fitting within the 5kW per phase rule.

Glen chose a unique path.

Solar Powered Hybrid AC/DC Air Conditioners

In his search for answers, Glen uncovered air conditioning units that run on either grid AC, or DC from a dedicated solar array. These hybrid air conditioners1, without any ability to sync or return power to the grid, neatly and legally evade DNSP grid connection rules.

Glen highlighted the appliance’s versatility with its three distinct operating modes:

  • Completely off-grid, running solely based on what the solar panels produce.
  • Grid-connected with an AC limiter on, drawing a capped 400W from the grid.
  • Grid-connected without an AC limiter, allowing the appliance to pull extra power from the grid, ensuring it runs at peak capacity.

“Wanting to remove my old gas fire and to trial a Solar AC/DC split air conditioner in October 2021 I installed a 5kW unit in my lounge room with 7 x 370W solar panels. The unit has performed as expected so I decided to replace the conventional AC installed in the upstairs room with another 5kW Solar AC/DC unit.”

“Last summer, the two Solar AC/DC air conditioners, by leaving them off the grid, simply starting in the morning as the sun rose and shutting down as the sun set, kept my house temperature controlled. With the assistance of a wood fire, the same is generally applying this winter.”

Hybrid Solar AC DC air conditioner

Solar ACDC Split Hybrid Air Conditioner – no batteries needed! Image: Solar ACDC


But Glen didn’t stop there!

Solar Powered Hybrid AC/DC Heat Pump HWS And Swimming Pool Heat Pump

In his research, Glen discovered the emerging Solar AC/DC Heat Pump for hot water and the Solar AC/DC Pool Heat Pump Heater/Cooler. Both could be powered by the grid or independent solar panels—no batteries required. Taking a chance, Glen equipped his home with these innovative systems and the necessary solar panels.

“Since commissioning the HWS has not drawn any power from the grid and is now off the grid. I am extremely confident that by giving it priority use of the 14 panels it will remain off the grid even under extreme periods of low solar production.”

“The pool heat pump is also performing to expectations. In the week it has been connected (running from about 10 am to 4 pm) it has raised the 60,000 litre pool temperature by about 5 degrees. It will soon have it warm enough for exercise swimming. I am also looking forward to it keeping the pool cool enough as summer progresses.”

In just about eight months post-installation, Glen reports a mere 29 kWh drawn from the grid, while sending back 3,570 kWh.

Rooftop solar arrays City of Canning Western Australia

Harnessing More Solar Within the Rules

Tapping into the potential of hybrid AC/DC systems is a clever way to maximise solar usage without breaching network constraints. The absence of a grid-tied inverter means these panels fly under the radar during capacity assessments. Ensure your switchboard and grid connection can manage the load in grid mode, and you’ve got a winning setup.

A side note: Glen’s battery usage might not be optimal, but that’s a topic for another day.

DNSP rules, though seemingly restrictive, aim to balance a transitioning grid—one adapting to varied, sporadic energy sources.

We often challenge set boundaries. With a touch of ingenuity, you can not only make the most of your solar quota but also contribute to a steadier grid during peak demands.


  1. don’t confuse these appliances with ‘hybrid solar airconditioners’ from other companies that claim they use solar thermal to improve efficiency – Finn tells me he looked into these at CSIRO and could find no efficiency improvements
About Kim Wainwright

A solar installer and electrician in a previous life, Kim has been blogging for SolarQuotes since 2022. He enjoys translating complex aspects of the solar industry into content that the layperson can understand and digest. He spends his time reading about renewable energy and sustainability, while simultaneously juggling teaching and performing guitar music around various parts of Australia. Read Kim's full bio.


  1. Kingston says

    I don’t understand the problem he’s trying to solve. Aren’t network limits only imposed on what you export? There’s no limit on what you can use yourself from your own panels is there? Why can’t Glen stick those extra panels on his roof and use the excess solar to power regular AC units etc?

    • Finn Peacock says

      There is a hard limit on grid-connected inverter capacity and a hard limit on solar panel capacity relative to the inverter capacity (133%).

      • Ahh ok I think I understand. So my roof top solar totals up to 12kW and I have two 5kW inverters. So 10kW + 33% I’m under the limit. But the inverters are set not to export more than 5kW combined anyway because Powercor won’t allow any more than that, but is this limit of what is on my roof so that I don’t flick a firmware switch and start pumping more than my inverter’s rating plus 33% out? So is it to protect the grid? Or is it to prevent my inverter from going up in flames?

      • The hard limit on PV peak capacity relative to inverter AC output capacity is set by the inverter’s manufacturer, not the grid operator.

        Many inverters are quite capable of handling more PV than the 133% limit. The 133% limit is only relevant when claiming STCs (solar rebate) and doesn’t apply when system is combined with a battery.

      • I reckon solar panels hooked directly to a dc pump for pool heating is about as easy as it gets. Whenever its sunny my pool heats for free. I definitely don’t have to worry about cooling my pool though.

        • Yes Brad towards the end of summer my pool temperature makes it almost unpleasant when you are active in it.

      • Lawrence Coomber says

        Finn is correct:

        About the On-Grid hard limit, but what is not often discussed or well known by installers is that any premises in Australia [space permitting] is able to install an Off Grid System [system 2] up to 100 kW [minus the size of the On Grid System [system 1], and be paid STCs for that size Off Grid System.

        Example: existing On Grid System = 6.6 kW therefore Off Grid System 2 can be installed up to 100 – 6.6 = 93.4 kW. That earns a considerable STC’s rebate.

        This dual system scenario is quite common particularly in industrial applications for Single Circuit Loads that have an appropriate day time duty cycle; for example a metal guillotine; compressor; press; aerator motors for fish farms; water pumps for filling reservoirs on golf courses, mining operations. The list is long and flexible in the hands of an experienced Power Plant Solutions integrator.

        These principles are equally valid for domestic premises and of course can be integrated with any size storage stack.

        Lawrence Coomber

      • Finn, do you still get the benefit of STCs if the gear is off grid?

      • This doesn’t come up a lot IMO and seems to be mis-understood (for me anyway) – so have to ask and resurrect this thread while I can ask Finn!

        What exactly is the reasoning behind having both an Export Limit per phase (often now enforced in software/dynamically) and a hard-limit/nameplated Inverter capacity limit per site?

        Context in relationship to EvoEnergy ACT DNSP IES requirements for small scale solar.


        • Finn Peacock says

          I would say if the generation limit and the export limit are the same value then it is pointless.

          If the export limit is lower than the generation limit, then that makes sense.

          • So in relation to “it makes sense” when Generation Limit =, Export Limit is the part that throws me.

            Export Limit is controlled as a function of Inverter Generation – Self/Home Consumption. The Generation is dynamically controlled to ensure Grid “sees” no more that the Export Limit, lets say 5kW after factoring in Self Consumption.

            Irrespective you can also set and lock the Inverter max generation to a soft value.

            So back to original point – in your opinion what is the sense in hard nameplated capacity limitations (which can be waived, but takes a lot of convincing)

    • Michael S says

      Interesting read. I am in Queensland and still get the premium FIT. My two biggest power consumers are my pool and my EV.
      I solved the EV issue by signing up to Ovo EV plan. On this plan any electricity consumed between midnight and 6AM is only 8cents per kWh.
      I solved the pool issue by installing a hybrid solar pool pump. With this I can add more solar panels to drive the pool pump as it is semi off grid. When the sun shines, pool runs for nothing. If not enough sunshine, I have the option to run on AC.
      If I added more panels to the existing solar, I would lose the premium FIT.
      This way I have reduced my overall imports from the grid and maintained my allowed exports. End result is an expected yearly credit of $600, which will pay for the new pool pump in a year. However I also had to replace the old pool pump anyway.

  2. At 4.8kw (synergy see it at 5) I am already on the limit of inverter capacity if I want any FIT.

    • Kingston says

      So basically you’re separately Solar powering various appliances to allow more of your original roof top Solar to go to the grid? Is that correct? As opposed to increasing the production of the entire system. Because that’s not allowed above a certain value. Clever.

  3. Kim, this is really interesting. I know you are careful about promoting things but are you able to publish the name of the supplier of the units in this article. I did google the device type and found one supplier but they did not answer a phone call. Second thing I note Glen is an engineer did he do his own wiring? I am in WA and tried to get something similar done and could not find a licensed electrical contractor willing to do the work which was frustrating. Ian

  4. Kim, by installing a second PW2 the aim was:-
    1. To increase the max draw allowed by Western power from my system and
    2. Increase storage capacity.
    Both of these situations have come into play since the installation and as such I didn’t miss my mark. The mark was never an economical one.

    • Kim Wainwright says

      Hi Glen, well your mark was spot on then. As I previously said, there are other reasons for installing batteries, including backup and minimizing grid dependence, so well done on those fronts.

      As far as giving you “more draw allowed by Western Power from your system” – another Powerwall won’t always help you. If you’re drawing close to maximum demand power from one battery then put on the kettle plugged into a power point on the same phase, the other battery isn’t magically going to step in to take up the slack if it’s wired into another phase.

      If you’re aware of which appliances are wired to which phase you can manage your power use accordingly to avoid the grid. It looks like you’ve done that pretty well by the grid import figure you’ve given.

      • Kim, yes backup has been handy. We don’t have many power outages in my area but due to a power pole being taken out we had a 12 hr one and as well as my fridges an extension cord over the fence kept the neighbour’s one running as well. Of cause the Solar ACDC equipment kept on going. Installation of home batteries also helps the grid in several ways.
        Home batteries are being charged midmorning, midday when the grid doesn’t really want solar power being exported then this power is used early evening when the grid load is still high.
        I need to do some homework and then think we need to discuss how multiple PW2s and the Tesla gateway work re your comments about maximum demand.

  5. I’m pondering splitting my house wiring into “on-grid” and an “off-grid” sections, and powering part of the house with an off grid PV and possibly also battery system. I have multiple lighting and power circuits already at the meter box, so it wouldn’t be all that hard or expensive, and I already have a 5 kW solar and battery. It’s probably not worth it economically at the moment, but at least I wouldn’t be restricted by so many rules, regulations and limitations as to what I can and can’t do on my own property.

    • Alan Mainwaring says

      I have done this myself .It has been going for six years.I can run 8kw from my two parrallel inverters. This may not be the most economic way but I am getting sick andtired of the energy retailers and theway they just make up rules that only work in their favour.

    • Richard Courtenay says

      Hi David, I have two switchboards, one grid and one off grid. I use the off grid ror lights, TV, computer, washing machine, fridge and freezer. I have a totally isolated tie between the boards with two changeover switches and breakers for those wet weeks when little charge comes in. 12 x6 volt 530 amp AGMs and a victron inverter complete my set up. I use the grid for a large house pump (need the starting amps) and welding etc. 15 years on I’m on my second set of batteries, the first one lasted 10 years.

  6. Erik Christiansen says

    Point taken on the very high ratio of battery capacity to PV generation. My brother has just on 20 kW of PV and 15 kWh of Zenaji LTO batteries. With their very high C rating, they can easily gobble the full array output when domestic load permits. Even when they are down below 30% overnight, they’re often fully charged by 11 a.m., and he’s exporting 10 kW for the rest of the day.

    The HWS is simply on a timer, to take some of the remaining excess. For the last year or two, the supplier has been paying him. He cashes it out when a couple of thousand dollars have accumulated. An extension, currently going up, adds two more bathrooms, so doubtless another HWS. That’s typically another 10 kWh of storage. Open up a bit of B&B on 11 acres of bushland on the very edge of suburbia, and the contribution to societal decarbonising steams on.

    LTO batteries are not cheap, but can opportunistically grab the whole array output, and fully charge in an hour or two of sunny gap between passing cloud masses. I’ll be settling for a large bank of LiFePO₄ cells, able to take significant power at an acceptable C rating. (>10 kW @ 0.6C is only 15 kWh, so pretty easy. And cheaper, though not as long lasting.)

  7. This is fascinating, Well done Glen

  8. I’m already powering most of our two homes (one property) with an 8kW hybrid off-grid system. It uses a small off-grid PV array to charge the battery, which then runs the house at night.

    In the daytime it passes through “grid” power, which is really coming from my grid-tied PV array. If the small off-grid PV can’t fully charge the battery, then the system requests supplemental charge from the grid-PV system.

    Our grid PV is maxed out (and like Glen the regulations have become more restrictive since installing it), so my only sensible option to get more PV and improve self-sufficiency was to take loads off-grid.

    Rather than a few specific appliances, I’ve taken the whole property that way, with the exception of a large aircon system, oven and cooktop.

    Water heater is powered from grid-PV with use of a PV diverter. In essence our grid imports are now confined to night time use of aircon and a bit of cooking.

    Way cheaper than grid-tied batteries.

  9. There is perhaps another solar option.

    My-PV has a DC resistive heating element that uses 750 watts from solar panels for around AUD$1,200.


    When there is no sun it uses the same heating element at 2,000 watts off alternating current.

    The installation does not require pipes; therefore, installation costs are simple. There are two PV solar cables from the resistive heating unit to the solar panels which are connected in series, and there is a standard alternating current cable to an electric outlet for days without sun.

    In addition, this installation does not require an inverter since the DC resistive element works directly off the solar panels.

    Maintenance costs might require at some point replacing the heating unit. However, this could be a DIY repair.

    Either alternating or direct current will increase the temperature in a water cylinder above 60°C.

    The solar panels can be installed on a dual axis solar tracker from Eco Worthy for around AUD$660. This will extend the morning and evening solar hours for the panels.


    The controller might need to be replaced at some point; however, this is, also, a DIY replacement.

    Add the cost of solar panels to the above, and you have a simple, efficient solution for heating water.

    My-PV has a calculator to estimate the percentage of alternating current required at different locations.


    Additionally, excess energy in the summer could be utilized for a dual direct / alternating current air conditioner, also, without an inverter.


    By the way the above setup with 6-solar panels produces at my location in excess of 2,500 kWh.

    To extend the energy a bit more into winter, I have been speculating of adding one additional solar panel. This would increase solar production to about 3,000 kWh.

  10. The maximum amount that I can add is dependent on a few constraints:

    1- the heating element allows a maximum open circuit voltage of 360 VDC at 10-amps.

    The amps are somewhat less of a problem since the heating assembly can limit higher amps to 10-amps.

    2- There is a second constraint due to a ground fault protection device installed which limits open circuit voltage to 300 VDC from MidNite solar.

    If I add more panels, I might have to replace it with a GFPD from Morningstar which has a tolerance of 600 VDC.

    3- Another limiting factor would be the breakers themselves which have a tolerance of 300 VDC, and I would, also, need to replace these.

    Keep these constraints in mind when you plan an installation.

    We don’t use hot water everyday; therefore, there is surplus energy most of the week. This surplus energy is used by the air conditioner.

    During the summer we have seen a decent reduction of electricity from our electric bill.

    In addition to having less parts that can go wrong such as with a more efficient heat pump hot water unit.

    This setup does not have the problems of leaking water pipes or additional water pipes associated with hot solar water collectors, and there is no need to replace the collector itself every 15-years.

    In addition, this setup works in the winter unlike solar water collectors, and if something should go wrong, I believe that I could handle it on my own. This should limit future maintenance expenses.

    No permits were required.

    This was another reason for doing our installation.

    Unlike solar setups with an inverter. Our installation did not require an inverter.

    This saved us both time and money since we did not have to wait for an inspection or installation permit approval, and we did not have to install and purchase an inverter.

  11. Lawrence Coomber says

    Be careful when describing system designs as Hybrid and On/Off Grid Solutions in the same breath. There is no such homogenous systems concept that passes both the CER Renewable Energy Act test and the AS3000 Electrical Safety Rules test. Be cautious.

    On Grid and Off Grid Solutions must be separate System Designs to qualify for STC’s; and it surprises me how few Solar Installers/Companies have so little technical and compliance understanding of the regulations; and the great benefits that can be gained by understanding this subject.

    Here is an example, that is transferable to all/any property or premises in Australia:

    Rural customers with a little bit of extra land than their city cousins, are in a great position to install a second Solar PV + Battery Storage Off Grid Solution on their property in addition to an already existing On Grid System.

    Importantly the second Off Grid Solution is entitled to STC’s and the System size can be quite large. The CER rule is that the second system plus the first system must in total be no greater than 100 kW. So if you have a 10 kW On Grid System you could install a 90 kW Off Grid Solution at the same premises, for a total of 100 kW of Solar PV Systems and receive the full quota of STC,s applicable to the location, for that second 90 kW Off Grid Solution.

    The optimum systems inter-operability functionality, including load circuits switching and control between the Grid Supply Source and the Off Grid Supply Source, will require the services of an Off Grid Solutions Integrator specialist experienced in these designs. There are many traps to become aware of for inexperienced players.

    Lawrence Coomber

  12. I asked a tradie about connecting the aircon to its own solar panels, and he shook his head and said it wouldnt work because the varying solar power would wreck the aircon. So I said wouldnt they just start up when there is enough power, and he again said no. I just cant believe thesepeople sometimes—surely thereis a way.
    Likewise, my pantry and my garage are quite decently lit in the daytime by two Bunnings solar panels on the roof, installed by moi. I am trying to get someone to put a line through to two very dark rooms in my house for something similar. I think I will have to clamber up there and do it myself, whereas a tradie could do it much more safely and quickly.

    • Robyn your tradie mate would be correct about a standard AC air con but the Solar ACDC air cons are very different. They are all DC and will run directly from the DC supplied by solar panels. When there is enough solar supply they start up and then shutdown when the sun drops off. If you want them to run when there is not enough sun they can be connected to the grid and via their own inverter change the grid AC to DC. My first Solar ACDC air con has been running like this for almost two years. It has the smarts to follow the solar output without any problems. If your tradie mate is still shaking his head send him to my place and I shall show him.

      • Kingston Eldridge says

        Hi Glenn, these are just Air Con is that correct? They aren’t reverse cycle and heat as well?

      • Glen, I’m in WA (albany) and am keen on the solaracdc hybrid aircon…can I just clarify that this is the brand you used, and that it’s readily available here in WA please ?

        • Hi Pamela,

          I bought from Rob last year, 2022, one unit. He represents both Superen and Solar ACDC

          He sent me a unit that must have been sitting on his warehouse for several years (sticker says 2015).

          It has been nothing but problems. It has an inherent earthing / grounding problem on the alternating current side.

          In addition, the unit is unable to perform adequately in temperatures above 35°C.

          I have been unable to sort this out despite having technicians both for air conditioners and for direct current, and I have not been provided with a satisfactory / alternative solution from Rob.

          The unit we got is unable to be installed simultaneously with any other device operating with an MPPT controller since the MPPT controllers will start conflicting among them.

          I am planning on getting rid of the unit I bought next spring.

          My future solution will be to install a Victron Multi RS 450 / 100 with a regular air conditioner and batteries. The solar panels will provide power to the batteries, and the air conditioner will work off the inverted alternating current from the Multi.

          This will allow me to expand my solar array (6-solar panels) and feed several air conditioners from the same solar array.

          This will allow me to use well known air conditioner manufacturers for space conditioning.

          The Multi is able to draw grid power as well, but it is unable to feed power to the grid.

          A possible downside to this is that I am unsure if I will need to apply for a permit or not since I am only drawing grid power, and I am not supplying energy to the same. This makes it safe for power line guys.

          • Glen Douglas says

            Interesting feedback Eric, that is disappointing. Where are you located? I would love to have a chat to understand your system. My first Solar ACDC Aircon was installed in October 2021 so has now worked without any problems through two summers and two winters. My second one was installed August 2023 has been working as expected. I haven’t noticed any problems with + 35 degrees days but don’t really have a way of really measuring that performance. I have had numerous phone calls with Rob and have always found him helpful.

          • I wrote the wrong date it was made in November 2018.

        • Glen Douglas says

          Hi Pamela,
          As listed above they are Solar AC DC see https://solaracdc.com.au/ I am in Perth My first one was supplied and installed by MLec and the second by Min Solar both Perth based but I don’t think MLec do them anymore. I am happy to be contacted directly via faced book if that is allowed by Solar Quotes. Regards Glen Douglas

          • Hi Glen,

            First of all I made a mistake on the manufacturing date. It was made on 2018 not 2015, but it was shipped to me on 2022.

            Second, the unit that I got is sold by Rob, but the manufacturer is Superen.

            Third, this unit has an earth leakage on the AC side.

            I am forced to physically disconnect the air conditioner every morning from the grid, and at the end of the afternoon. I physically disconnect the solar panels (with a breaker) from the air conditioner, and I turn on the grid electricity for the air conditioner for night operation.

            Fourth, I measure the inside temperature with an infrared thermometer. It is similar to a forehead thermometer.

            I will set up the air conditioner to 22°C, and the inside temperature will get as low as 24°C.

            Rob thought that there might have been a leak, but I had an air conditioner technician that charged me a lower rate since he said that missing amount was minimal.

            After his visit the inside temperature remained the same.

            The technician said to clean the outside since it was a bit dirty with dust. I cleaned it up, but the inside temperature remains the same.

            The temperature inside remains the same whether it us on DC or AC. It remains the same regardless of whether I set the minimum temperature of 16°C or 22°C.

            Rob suggested leaving it on auto fan since I had it on turbo, but the inside temperature remains the same.

            Fifth, based on your experience with the ACDC brand, it appears that the Superen and the ACDC air cons have different results. The one thing in common is that both are sold by the same retailer.

            I am glad that you have had positive results, and u wish I could say the same.

            Kind regards,

    • Lawrence Coomber says


      We are a long way behind worlds best practice in renewable engineering technology qualifications; skills; and training unfortunately, but there are better days ahead. If you doubt what I say, or my qualifications to comment: continue reading.

      Australian Industry Standards 2021


      Project Scope:

      The Renewables Training Syllabus project will review eight qualifications and fifty Units of Competency in the Electrotechnology Training Package.

      During transition to the 2012 Standards for Training Packages it was identified that renewable energy qualifications were NO LONGER FIT FOR PURPOSE.

      The review will update these qualifications and related units to reflect current technologies, industry practices, regulations, and accreditation.

      The Electrotechnology Industry Reference Committee (IRC) will have oversight of this project, which will be facilitated by Australian Industry Standards (AIS) in consultation with industry stakeholders.

      An expert Technical Advisory Committee (TAC) will be formed for this project.

      New Qualifications:
      UEE41920 Certificate IV in Electrical – Renewable Energy
      UEE42020 Certificate IV in Electrical – Photovoltaic systems
      UEE43120 Certificate IV in Energy Efficiency and Assessment
      UEE50720 Diploma of Renewable Energy Engineering
      UEE60920 Advanced Diploma of Renewable Energy Engineering
      UEE62020 Advanced Diploma of Engineering Technology – Renewable Energy

      New Units of Competency:
      UEERE0028 Design hybrid renewable power systems
      UEERE0029 Design micro-hydro systems rated to 6.4 kW.
      UEERE0030 Design renewable energy (RE) heating systems
      UEERE0031 Design stand-alone renewable energy (RE) systems
      UEERE0032 Design wind energy conversion systems (WECS) rated to 10 kW.


      Lawrence Coomber

  13. Matt Evans says

    Is it difficult (in terms of rules/legislation) or expensive in WA to convert a house switch board from single phase to three phase?

    As wouldn’t this also enable a larger solar system solution? Just wondering about cost benefits analysis of upgrading to three phase power instead of adding batteries??

    I do like the ingenuity and innovative thinking of the hybrid approach, particularly as we 50% WFH.

    • Kim Wainwright says

      Hi Matt. I just checked with an electrical contractor mate of mine here in Perth. He says to upgrade from single to 3-phase ball park figure from a contractor would be upwards of $1200 just for a basic switchboard plus $1500ish for underground mains. That’s not including Western Power connection fees. Of course, you would have to have 3-phase power available in your street to begin with. Yes, 3-phase power could potentially enable a larger solar power system. You’ll have to do the math on that one yourself my friend!

    • But if you still want to get a feed in tariff with 3 phase power you will still be Limited to a 5KW inverter.

  14. Kim I would like to read the footnotes for the Western Power table. I have looked but can’t find the table. Will you please post a link to it.

  15. I recently looked at a Battery to add to our solar. (inner suburb Perth) We generate more kWhr than we use. it was looking all reasonable until I started to do the sums.. What I found out is that the provider is reducing the cost of power during the “solar window” (8c), increasing the Super Peak charges (30- 50c) and reducing the rebates (2-3c). But the kicker was the increase in Connection fee that is around $450 p.a. Plus another $300-$500 for a meter upgrade. I asked if I could go Off Grid completely and the battery provider said it was against the law. Is that true?

    • Finn Peacock says

      you can go off-grid if you like – no one can stop you

    • That doesn’t sound right about the connection fee being p a (assuming you mean per annum) think it will be a one off.

      • Thanks all, It was Synergy (Chat) and Plico (Sales) who said it was not possible. The $450 p.a.refers to the $1.23 charged per day for being connected.

        • So by connection fee you are referring to what is called on your bill as the daily supply charge. My last had this at 97.9714 cents plus GST. I believe this has gone up from 1st July. We don’t get told until we get the bill. I don’t think this has anything to do if you have a battery or not. What supply tariff are you on A1? I am not clear on some of your first message. If you have a feed in tariff (FIT) oof 7 any time this will change to 10 cents between 3pm and 9 pm and I think 2.25 cents for the rest of the time. If you fit a battery it will be charging in the morning so you will be storing that energy that you now sell for 7 cents to use at night instead of paying 30 cents (incl GST). Also you will get 10 cents for the energy you export after 3. For my last bill (June/July) I received $14.40 for my export vs $19.80 if I had still been on the 7 cent FIT so a loss of $5. During this two month period the energy sent to my battery could have been exported with a FIT payment of about $32 while it saved me $109 in imported energy. So I saved about $77 (109-32-5). Interestingly for Dec/January the saving was $45 (93-27-21) Interesting figures. I may have to check them tonight but have done so a couple of times now. There will be a little in accuracy because I have used some monthly figures from my Tesla app and some figures from my Synergy bill which is on about the 4th of the month.

  16. Kinston they are reverse cycle, they heat and cool.

  17. Lawrence Coomber says


    What technical circumstances have motivated your interest in 3 phase mains power source over your existing single phase?

    Do you have [> 15kW] 3 phase machinery; motors and/or pump motors at your place?

    If so then then you still don’t need 3 phase if your 3 phase motors duty cycle is light usage [use a properly sized silent 3 phase gen set for light usage 3 phase machine loads]; it is common practice and low cost.

    Machine Duty Cycle [hours of operation per day] plus Load Diversity, are the two most important factors that system designers consider for both On and Off Grid System Designs.

    Remember Network Maximum Demand Tariffs are determined by your premises Loads. They determine the mains cable size required to be connected to your premises. The bigger the cables the more expensive.

    There are many cost effective design options available for your particular requirements Matt. Talk to an experienced Integrated Power Plant Design Engineer is my suggestion.

    Lawrence Coomber

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