How the new solar standard will affect households – like mine

How the new solar standard will affect households – like mine

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Drawing from personal experience, a look at what the new national standard for solar installation could mean for home solar and battery plans.

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A new standard is in force, restricting single phase solar PV (and battery storage) to just 5kW.

I understand this standard is “national” and is just coming into force. If you want to have more than 5kW in your house (the vast majority of residential houses have single phase power) the options are:

  1. Install a three phase power system. I understand the cost of this is typically around A$1 k to A$2k, but I don’t have much data to support this. However, even then costs go up because either a) you have to have the same amount of PV on each phase. So this will likely mean reconfiguring your existing system, or b) buying a 3 phase inverter. The cost for this is likely to be $A1 k higher than the typical inverter costs. And quite possibly your choice is lower.
  2. Restricting output to 5KW. I understand from my friendly retailer that whereas previously this might just have been a “tick the box” approach it’s now likely to require some hardware. But I don’t know the cost of the hardware.

A battery may require more PV

Residential batteries are expensive, at best, around $A1000/kWh of storage installed. The reality is that they are most likely to be installed first in houses that can afford them. The further reality is that these houses are likely to have higher than average electricity consumption. I am an example of this.

Our house is a 1950s build (read energy inefficient), has a swimming pool, some air conditioning (not used that often), and in winter, quelle horreur, other members of the household have been seen turning on electric radiators on the seemingly spurious grounds that “it’s cold”. (“What’s wrong with a jumper?” I plaintively ask. But I get short shrift.)

So we only have 4kW of PV (Trina panels with micro Enphase inverters). They face north, and over the past 12 months the Envoy system tells me my capacity factor was 14.7 per cent and average daily output 14.5kWh.


But that’s nowhere near enough to run the house. Thanks to AGL having promptly installed a time-of-use communicating meter, and assuming I have manipulated the data properly, my daily load profile is shown below. The colours on the figure represent peak, shoulder and off-peak consumption.

Figure 1 Energy bandit residential load profile. Source AGL data and ITK analysis
Figure 1 Energy bandit residential load profile. Source AGL data and ITK analysis

If we look at that in dollar terms I made the following calculations. Note that the $ amounts are not adjusted for weekends (no peak on weekends) and are before the AGL usage discount so they overstate the peak cost. I ignored the discount on the basis that I think the price next year will be 20 per cent higher.

Figure 2 Residential bill analysis
Figure 2 Residential bill analysis

My conclusion is that if I can fully utilse a 7kWh or larger battery I can go close to eliminating $1250 a year of peak electricity charges.

But the existing PV system only produces average daily exports of 4kWh. This shows that, by accident, I sized the system quite well in that about 75 per cent of production is behind the meter. However, allowing for winter decline in PV, I probably need a further 2-3kW of solar to go with the battery.

It seems that due to the change in standard this is going to be expensive. The battery itself won’t be cheap. Quotes for the installed cost of the Tesla Powerwall 2 are coming in at around $11,500. So the payback periods are marginal. If I add in the 3-phase cost, its going to be more of an ideological than an economic decision, for sure.

David Leitch is principal of ITK. He was formerly a Utility Analyst for leading investment banks over the past 30 years. The views expressed are his own. Please note our new section, Energy Markets, which will include analysis from Leitch on the energy markets and broader energy issues. And also note our live generation widget, and the APVI solar contribution.

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  1. howardpatr 4 years ago

    This is being done for the interests of owners of the networks and generators.

    So short-sighted, especially when you consider that it won’t be too far down the track that homeowners will be wanting to charge their EVs and heat their hot water with their rooftop PV. For those with the roof space 10 kW plus will become the norm.

    Hopefully this matter will be aired in the Senate instead of being snuck through by an agent of the vested fossil fuel corporations.

    • Kevan Daly 4 years ago

      Conspiracy theories won’t work here. It’s because if there is an abundance of solar the current through the nearest street transformer will reverse and consumers will be subjected to overvoltages depending on how far they are from the transformer.

      • neroden 4 years ago

        Eh, happens to the grid already here in the US (thanks to unreliable generators and unreliable load levels) — who cares? We have to tolerate very large voltage fluctuations.

        I understand that they wouldn’t want an entire neighborhood feeding the same phase, but normally you have each house on a different phase. So if I’m feeding in on one phase, my neighbor’s solar should be feeding in on a different phase, and it should all balance out.

      • howardpatr 4 years ago

        It will not be too far down the track when consumers will want/need rooftop systems bigger to supply energy to their EV.

  2. George Darroch 4 years ago

    It sounds like you’d be better off with further investment in insulation and efficient appliances and systems.

    • Jason 4 years ago

      Retro-fitting insulation to an old house can also be pricey. If you have to tear out walls, it can be a more emotional than economically rational choice.

      But the difference in how a room feels in winter – warm all through the room, not just next to the heater, and using less power to do it – that’s a very nice emotion.

      • George Darroch 4 years ago

        You can do a lot with interior surface (wall, roof, window) coverings. Not as effective, but usually not as invasive or costly either.

  3. Craig Allen 4 years ago

    Is it not possible to get an battery-inverter-software system that limits the output to grid to 5KWh regardless of the size of the array? If not then the manufacturers/installers should get onto it ASAP.

    • MaxG 4 years ago

      Selectronic’s SP PRO GO can do this without any problems… I have 12kWh in panels on 2 x 6 kWh inverters feeding into a SP PRO which limits the export to 5kW/h and throttles both inverters to produce my base load + the 5kW/h for export.

      • Trent Deverell 4 years ago

        ….or think outside the square as i did two years ago and install a 2nd system…. being a Victron ES battery-standalone system with its additional 1.6kwp solar array to run the computer room load and with battery capacity kept in reserve it also provides a handy UPS with many hours of run time.

        In effect I wound up with 7.6kwp of PV in total, and this releases more of the 5KW SMA inverter system to cover hot and heavy use days… but I still stay compliant with 5kw feed-in limit mandated in Queensland.

    • solarguy 4 years ago

      Since the 1st of this month they are not allowed to be installed. Yep, April fools day, ironic isn’t.

  4. Melodie de 4 years ago

    I’m not sure what the problem is? Most countries tend to require a push towards 3 phases production above a certain threshold, and whilst 5kW (5KVA I suppose) isn’t the highest threshold, it’s not out of the norm. the request isn’t unreasonable. What you might want to do is first, think energy efficiency, second, inquire if the threshold is kWp or kVA (based on inverter max power), et check if maybe you’de be better of with a peak capping system or installing your system east/west to reduce your peak injection (and hence remain under the threshold)

  5. Jonathan Prendergast 4 years ago

    It’s worth putting in an application to your DNSP to get a larger system. While it may be a blanket rule, in suburbs with less rooftop solar pv penetration, you might be surpised and get approval. I did last week.. But I wouldn’t like your chances if you lived in QLD or SA where there is lots of rooftop solar.

  6. Malcolm M 4 years ago

    Why would this be a problem with feed-in but not withe load ? Why do they not require 3-phase for any load over 5 kW?

    • neroden 4 years ago

      They want to attack solar.

    • solarguy 4 years ago

      They do require 3 phase inverters over 5kw output!

    • baseload renewables 4 years ago

      The grid’s been designed for one-way power flow; renewables at the home introduced two-way flow. Too much distributed production on an LV line can cause voltage rise issues; distributors must adhere to certain limits in their provision of power supply to customers (also keeping in mind that our electrical appliances and power supplies are designed to certain standards and tolerances). Furthermore, too much distributed production connected to a distribution feeder can result in reverse power flow. Just as under-production requires load-shedding, excess production must be dealt with, more or less instantaneously (hello grid storage?). Both of these issues add expense to grid operations.
      Extra load does add expense in the sense that if upgraded distribution transformer/conductor/substation capacity is required, that adds expense, but I’m guessing that this expense is covered by the extra income, over time, garnered by the increased load.

  7. John Mitchell 4 years ago

    We have a 5 kw Solar array & 1 LG6.4 kw Chem battery, run by a Solax X Hydbrid Inverter. This inverter has a power management system on 2 different models. We have the C (city) model and the other is the E model. The E model has the EPS (emergency power system) for blackout situations. As we live in the ACT, its very unlikely that we will need the E version, although if I knew about it before hand, I would have installed it. Both versions can charge batteries from OFF Peak power which I have trying this week to over come the peak period. Since our last meter reading in Jan. 17, we have imported the following: PEAK 19 kw, Shoulder 20 kw & Off PEAK 65 kw.
    We have used a total of 650kws and the imported component of this is 119kw, 65 being OFF peak.
    We have exported 1608 kws @ 0.075 cents. The cost in total for our imports is $11.55.
    The reason for my testing is to overcome the morning peak (2 hrs) @.255 cents per kw with the use of RCAC for heating. This is backed up with an R8 ceiling & R 4 brick veneer insulation walls.

  8. neroden 4 years ago

    So the new regulations are a deliberate attack on solar installations — that’s what I’m getting from this. Those who are rich enough will install big batteries and 3 phase power, or install big batteries and go fully off grid.

    (Tesla Powerwall 2 prices are going to come down. Your quotes are SERIOUS PRICE GOUGING and I would absolutely order direct from Tesla and get a buddy with an electrician’s license to install it, faced with quotes like that. Electrical work is tricky, but it doesn’t justify a $3000 markup, which is what you’re seeing.)

    The poor and middle class are the ones who are being attacked by these regulations.

    • humanitarian solar 4 years ago

      It might be necessary for Tesla to include an “adjustable export control” like the Selectronic SP Pro.

    • humanitarian solar 4 years ago

      solarguy has said “the network won’t allow adjustable output inverters anymore for residential” so I guess that means the inverters with “adjustable export control” can’t be used anymore. Seems very prescriptive and untrusting, that perhaps we would program the 5kW export level – then crank it up later!

    • humanitarian solar 4 years ago

      I’m trying to understand how the Powerwall 2 works. Now that there’s this new rule about an Australian 5kW inverter limit on exports, it appears to stop people stacking multiple Powerwall 2’s side by side and doubling or tripling inverter output power? It’s great the Powerwall 2 inverter happens to be the ideal 5kW output because that appears to fits the rules perfectly and the battery is large anyway. The only issue I see, is I can’t find specs on how many kW of PV can be connected to a single Powerwall 2? Is it an exclusively AC coupled system? If so, is that an issue with the new 5kW export rules? If AC coupling has a 5kW cap on it’s limit, I don’t know if there is any other way to get power into the battery because I don’t imagine there’s battery terminals and no other solar controllers will operate at 400V+. Especially with EV’s coming, I think it’s important how many kW of PV can be connected to a single Powerwall 2? As far as I can see, I think there needs to be DC coupling. This may enable people to add more PV than 5kW if it presently happens to be AC coupled. There’s also the issue if load management features are worthwhile, of potentially being able to control a couple AC circuits or load shed in grid outages. The goal posts are moving for all of us and it’s hard getting our heads around these changes and keeping up with them. Is there more info somewhere?

      • baseload renewables 4 years ago

        I see continuous maximum charging spec’d at 5 kW / 5.8 kVA for the battery, so that seems to me to be a rough guide to the max PV specs. The “typical system layout” appears to have only the single DC/AC converter but I’m guessing there’s some rectification/chopping going on inside the box, given the 50 VDC internal battery voltage spec.

        • humanitarian solar 4 years ago

          Finn Peacock has written a blog article about whether it is legal to connect a PW2 to a grid. Seems it’s all become a matter of discretion for networks. Great to hear it has the 50VDC internal battery spec because perhaps it could be redesigned to be DC coupled and even use conventional MPPT’s to feed it.

  9. humanitarian solar 4 years ago

    Here’s a product with an “adjustable export control”

  10. humanitarian solar 4 years ago

    “Restricting output to 5KW. I understand from my friendly retailer that whereas previously this might just have been a “tick the box” approach it’s now likely to require some hardware. But I don’t know the cost of the hardware.”

    I assume you saying that at one stage purchasing an inverter/charger with an “adjustable export control” would have been an initial investment option, though as your committed with pre-existing hardware before the rule change, this feature could be harder to integrate in retrospect.

  11. humanitarian solar 4 years ago

    Is it possible to AC couple the 4kW of micro inverters onto the output of a battery inverter and use a model with an “adjustable export control” set to 1kW, so then you know the maximum total exports will be 1kW + 4kW = 5kW? The advantage of this strategy is you could still have other solar systems on the property, as long as they were all located behind the battery inverter with the 1kW export limit. Or is there a way to configure the 4kW of micro inverters behind the battery inverter as well, so all the solar is subject to the “adjustable export control” of the battery inverter? Sorry just questions because I don’t know anything about configuration of micro inverters.

    • humanitarian solar 4 years ago

      Sounds the best solution is working out how to feed the micro inverters into a battery, along with all other future PV and only have one battery inverter with the “adjustable export control” mediating the relationship with the grid. You can have as many solar systems on your property as you want with as much PV as you want, just only have your one premium inverter/charger exporting to the grid with it’s export control set to 5kW. You could still even have other solar systems connected to the grid, though for those just only buy an inverter/charger with a charging facility or program those inverter/chargers not to export. That’s what I’m doing. Three inverter/chargers in seperate buildings all sharing power, though only one exporting to a grid connection.

    • solarguy 4 years ago

      The only problem is the network won’t allow adjustable output inverters anymore for residential.

      • humanitarian solar 4 years ago

        oh f__k. That would appear to mean having a 5kW inverter (nominal?) mediating the relationship with the grid then doing whatever we want elsewhere on the property, even if only with inverter/chargers with charger only function (no exports)? I think this also lends itself to using Victrons quattro model and connecting solar systems behind the meter, so at least they can share power.

        • solarguy 4 years ago

          HS, as long as (5kwP) it doesn’t go back to the grid, well fine, but I don’t know how you would separate that.

          • humanitarian solar 4 years ago

            I currently have a middle building with PV/battery and a Victron inverter/charger. Generally speaking, this solar system has excess power so when I install another solar system on the house, I was thinking of using Victron’s Quattro model which has 2x external AC inputs. This means the Quattro for the house could manage one external AC input for the grid (and export 5kW) and also have the other external AC input from the middle building to receive that buildings exports. This would be good because the house is short on good roof space and would enable the Quattro to control exports for both solar systems. So in summer what would inevitably happen is the middle building would be exporting to the house Quattro (on external AC input 2) and if the Quattro’s batteries and load are taken care of, it would then export the exports of both solar systems out to the grid (on external AC input 1). I think.

          • solarguy 4 years ago

            Yeah, on the face of it, it might work.

          • humanitarian solar 4 years ago

            Here’s the Quattro. It has a 5kVA model.

          • solarguy 4 years ago

            Cheers mate.

        • solarguy 4 years ago

          Umm……….. If the second inverter doesn’t have the ability to frequency shift, then it will not control it’s output going into the Quattro.

          • humanitarian solar 4 years ago

            I think what happens is when the shed inverter/charger goes to export, it syncs with the grid (in this case the Quattro which is synchronised with the grid). I’m also wondering if the Quattro can frequency shift because what if it has two different AC sources and it can’t make them in phase i.e. a diesel generator and a grid (in countries with a weak grid) or diesel generator and an AC wind turbine?

          • solarguy 4 years ago

            HS, best to talk to Victron.

  12. George Michaelson 4 years ago

    For a neophyte like me you missed a sentence. you install 3-phase in order to .. be able to break a single phase 5k limit and so implicitly get PV and battery north of a market required cap on 5k? Is that it?

    • humanitarian solar 4 years ago

      Its that they want to limit us so we don’t export too much power unbalancing their grid, so apparently they are limiting us to exporting 5kW per phase, so if we got three phase power connected to our properties, we could for example have a 5kW inverter exporting on each phase, so 15kW of exports in total.

      • George Michaelson 4 years ago

        Right. and then you have to balance load onto phases inside the house, or have something smart to switch circuits to phases, or whatever else makes this fly. The one thing you can’t do is shift the peak generation window because thats locked to time of insolation, so it winds up being 3 phase with more batteries because the law is the law. Of course at some stage, they (for some value of they) write 3-phase out of the equation. Stupid, but predictable. “you can’t do that because we don’t want you to do that”.

        Basically that sentence you wrote above is it. I just expected to have read it sooner in the article. I probably skipped too fast.

        • humanitarian solar 4 years ago

          Sorry I don’t know. I’m an electronics technician not an electrician. I’ve never worked with three phase applications.

  13. humanitarian solar 4 years ago

    As far as I understand, we could still DC couple solar and wind directly onto the battery and have unlimited onsite power, it’s just that only a 5kW inverter/charger could be wired to the grid. See equipment diagram. Solar and wind feeding battery via their solar controllers directly into the battery.

    • humanitarian solar 4 years ago

      You could still export an incredible amount of power with a 5kW DC coupled system like this because it can have unlimited PV connected to the battery. Most people with a 5kW grid-tie inverter probably only have 5kW of PV connected, so it will only be exporting at maximum on the rare occasions the solar system is cranking hard in summer and the load is already taken care of. In contrast, the system above could be cranking out 5kW in exports all day because it could be set up with say 15kW feeding it, guaranteeing it will still be exporting 5kW in marginal conditions in summer, with plenty of onsite power for winter! So there’s plenty of onsite power and probably enough exporting for between 1 and 3 other houses I reckon.

    • humanitarian solar 4 years ago

      The advantage of this setup is there is an unlimited number of PV strings that can be connected to the battery via a solar regulator. A battery inverter with its own MPPT inputs usually only has 2 which could be a limitation for people with lots of small rooftops with different orientation and slope.

  14. solarguy 4 years ago

    David, There is a very good solution for you, but first here are the rules. Inverter output can only be 5kw on a single phase as you know, however that doesn’t stop you from having 10kw of PV!

    The CER will only allow STC’s to be claimed on + 33% of PV oversizing on an inverter, so with a 5kw inverter, that’s 6.65kw of PV. Any PV above 6.65kw you won’t be able to offset the cost with STC’s past that point. You will have a slight extra cost on a 7kw Array, more over that size of course.

    As I am a CEC accredited designer you can take the following advise I give you or ignore it, your choice.

    1) Ditch the Enphase micro’s and install a DC coupled 5kw hybrid inverter. The Sungrow is a good performing hybrid at a reasonable price, has all the monitoring you require and dual MPPT input. Install 2 x GCL 5.6kwh usable batteries for 11.2kwh of storage and your extra 3kw of PV. Both can be mounted on a wall outside as their IP 65 rated. An LG Chem 10kwh battery is also an option, also IP 65.

    You can flog off the surplus micro’s.

    It’s the simple and cheapest way out of trouble.

    If you would like to discuss this further Giles has my phone number.

  15. Eastern Trisha 4 years ago

    I installed 3.5kw because when I applied to AGL to install 5Kw they rejected it and said I could only have 3.5.

    • humanitarian solar 4 years ago

      I guess your referring to upgrading a 3.5kW grid-tie solar system to a 5kW grid-tie solar system. If so, I’d enquire with AGL you wish to discard the grid-tie inverter and instead install storage and check the 5kW battery inverter limit applies.

  16. Jeff Wehl 4 years ago

    The new SolaX X 3 phase hybrid will be the game changer here. Unbalanced 3 phase output from a single battery pack and scalable ie install 3 x 5kw inverters with 3 battery packs. Alternativley, single phase customers will convert the grid to a charger and go offgrid.

  17. humanitarian solar 4 years ago

    I think the main point is, the rule change mainly effects grid-tie inverters as it’s an inverter kW limit, not a limit on the amount of PV that can be fed into a battery. If so, people can still have plenty of PV for their future EV, we just can’t export more than 5kW to the grid at any given time.

  18. Mark Lavis 3 years ago

    Interesting discussion- Just came across this as i’m investigating a knock down rebuild replacing a 0.5 EER house with a 8.5 EER all electric passive solar design house with space for up to 15kw of rooftop solar. In the ACT the cost for upgrading to 3 phase is $780 (on top of the knock down rebuild fee of $2892). I only started investigating the 3 phase option once I started looking at larger inverters- by the likes of Fronius and SMA. 3 phase seems to make sense if you are ever considering an electric car in the future -reducing charging time significantly. For me the common sense approach still appears to be consuming as much generation behind the meter as possible. At the moment batteries are an expensive way of doing that. Using your excess PV to run an ASHP that can provide domestic hot water as well as space heating and cooling (like the new Daikin Altherma 3) would appear to be a much better value option.

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