How 3-phase trickery from utilities is ripping off solar households

Print Friendly, PDF & Email

Electricity networks have spotted a pile of solar owners’ cash on the floor and have figured out how to covertly take it from under their noses.

share
Print Friendly, PDF & Email

networksIt seems some electricity networks just can’t help themselves. They’ve spotted a pile of solar owners’ cash on the floor and have figured out how to covertly take it from under their noses.

And the scariest part is this:  the solar owners being royally screwed will probably never understand why their bills are 30, 50, 80% higher than they should be. Indeed many of them will jump on online forums and Facebook to declare that solar is a complete con. They’ll extoll their friends not to waste their cash on it. The PR people at the electricity companies must be cracking the champagne.

So what are some networks doing to sneakily reduce the payback of solar systems? Well, it’s not a price rise and they haven’t hatched a plan to make people use more power.

Rather, they appear to have simply engaged someone to change a handful of lines of computer code, cleverly rejigging the way some import export meters define the “Net Export” of a kWh of electricity.

You may have thought that the term “net export” is pretty clear-cut? Surely it’s simply the number of kWh that, due to the laws of physics, flow out of the home into the grid whenever more solar is generated than consumed on the property?

On a property with a single phase supply, yes, it is pretty clear cut. The ambiguity arises where the home or business has three phase power.

Some networks appear to be taking advantage of this grey area. Many solar owners with 3 phase may never even know that the box on their wall that silently counts their solar exports has now been subtly reprogrammed to increase their bills.

How can this three phase trickery happen? Here’s how:

Many homes in Australia have a 3 phase supply. Many 3 phase homes who have solar have a single, 1 phase inverter connected to one of the home’s phases (usually the blue one).

This is a perfectly reasonable way to install solar. My personal solar system connects to a single phase of the house’s 3 phase supply.

The house’s 3 phases are then connected to a 3 phase solar import/export meter. This meter calculates how much solar is exported to the grid, and how much of the solar energy is being ‘self consumed’.

For most homes, self-consuming solar energy saves about 35c per kWh. Exporting solar energy is generally worth only around 8c per kWh.

So obviously you want to maximise self-consumption and minimize exports.

How 3 phase meters usually calculate exports:

Traditionally all 3 phase import/export meters have calculated exports like this:

1) Look at the total amount of energy being consumed on all 3 phases

2) Look at the solar being generated on the single ‘solar’ phase.

Subtract (1) from (2) to calculate the exported energy.

This is good for the homeowner. If the sun is shining and they are generating, say 3.5kW of power, but their appliances are consuming 1 kW on each of the 3 phases, they are officially exporting 0.5kW (3.5kW – 3kW) and importing zero kW from the grid. So they are earning about 4c per hour for their efforts. Not a lot, but better than paying for electricity!

How 3 phase meters could be hacked to benefit the retailers and networks:

Let’s stay with the scenario above and consider what is actually happening to the electrons in the 3 wires.

On solar phase, we are generating 3.5kW but consuming 1kW. Therefore we are sending 2.5kW back to the grid on the solar phase.

On the other 2 phases, we are consuming (importing) 1kW per phase.

So if the meter gets reconfigured to only count exports on the solar phase, then the financial effect is this:

The homeowner will be earning 2.5 x 8c =  20c per hour for their exports. But will be paying 2 x 35c = 70c per hour for these imports. The net effect is a cost of 50c per hour to the homeowner instead of them earning  4c per hour.

Do you think the electricity retailer would prefer to pay out 4c per hour or earn 50c per hour from hundreds of thousands of 3 phase solar homes with a 3 phase supply?

According to my contact, he’s tested some 3 phase meters and has discovered that at least some 3 phase meters in NSW are configured the latter way: i.e. to calculate exports only on the solar phase, to benefit the electricity company at the expense of the unknowing solar owner.

To my knowledge, there is no standard or contractual basis to enforce how these meters should calculate the exports. The electricity companies that own them may well be legally able to change the software in the meters at their whim, as I’ve never seen it specified in a supply contract. If anyone can clarify the legal definition of “net metering” please let me know in the comments.

Further, my contact told me that the networks are refusing to specify on paper how their 3 phase meters calculate exports.

What should a solar buyer with 3 phase do to protect themselves from being charged for these ‘phantom’ imports of electricity?

One option is to get a 3 phase inverter. Unfortunately this will add approx. $500-$800 to the price of a 5kW system compared to using a single phase inverter. It will also simply spread the exports evenly over the 3 phases. So you can still be generating more than you are using in total, but get screwed because the generation does not exceed consumption individually on all of the 3 phases.

If you want to use a single phase inverter (or microinverters) you should ask your electrician to connect as many daytime loads as possible to the solar phase. Ironically, the electrician has a duty to “balance the phases” with the loads, so by helping you not get screwed by the networks, they are actively decreasing the stability of the network’s beloved grid.

I’ve checked the meter on my home (a Landis+Gyr  EM5100 provided by SA Power Networks) using a 3rd party energy meter and it calculates net exports the correct way. But I’m very aware that they could simply upload new firmware to re jig the export calculations. Perhaps after reading this they will.

Finn Peacock is ex CSIRO, a chartered electrical engineer and the founder of SolarQuotes.com.au . This is an edited version of a blog post that was originally published here. Reproduced with permission.

Print Friendly, PDF & Email

39 Comments
  1. Geoff Bragg - SEIA 4 years ago

    In my experience, Essential Energy meters tally the kWh exports in the fair & correct way. A full discussion, testing by Essential Energy metering lab at Tamworth is available for SEIA members at http://seiaforum.com/showthread.php?275-3-Phase-Nett-Meter-with-single-phase-inverter .
    I don’t have direct experience of other DNSP’s metering behaviour, however, I have questioned Ausgrid & Endeavour Energy at our SEIA NSW 2013 meeting, and both indicated they believed their metering adds the 3 phases of loads, and subtracts the 3 phases of exports to arrive at the net energy reading for that instant.

    From the Essential Energy document on their meters: “The EM5100 & Sprint
    meters may be used for principal tariff, controlled load and both gross and net grid
    interactive applications which involve either multiple inverters or multi-phase inverters.” see full document here: https://www.essentialenergy.com.au/asset/cms/pdf/contestableWorks/CEOM8014_50.pdf

    I’m looking forward to hearing which DNSPs do otherwise…

  2. Terry J Wall 4 years ago

    Thank you for the warning Finn. Think I will go OFF GRID. It appears to be the only way to guarantee some genetically defective CEO is not screwing you.

  3. Alex 4 years ago

    Ausgrid’s ES3 Part A 2.7.4 Outlines that they use Poly meters and do it the correct way so if that “some areas of NSW” is in the Aus-Grid network then some more questions need to be asked: http://www.ausgrid.com.au/~/media/558381658BE642039EB0A4735D2A234B.ashx

  4. Nathan M 4 years ago

    While the the first calculation method proposed is the simplest, I’m not sure it’s the fairest…

    the phases aren’t one big bucket of energy – there’s three sets of generator windings, three sets of cables and three sets of losses. If you reduce your demand on one phase that’s great, but you haven’t reduced the load on the other two phases at all. In fact, the more you unbalance your system, the more you’ve loaded up the neutral and increased losses, all the way back to the transformer.
    Just because you choose to “net-off” the energy flows at the meter, doesn’t make the import a “phantom” import.

    It could be argued that averaging across the phases compensates the PV system for a benefit it didn’t provide.

    Yep, the murkiness around the calculation method is dodgy because it leaves people confused and changes could negate an existing assumed benefit, but it’s down to PV retailers and installers to understand their customer’s usage pattern and provide solutions that are less exposed to these sort of retailer billing shenanigans.

    For mine, the benefits of using three phase inverters on three-phase connections far outweigh the downsides. For a start, based on 35c for import and 8c for export – spreading the generation over three relatively evenly loaded phases and reducing import on all of them is going to give an equivalent benefit no matter how the retailer calculates the bill. Not only that, three phase inverter connections are typically exposed to a far less rigourous connection investigation which speeds up the process significantly.

    Furthermore, a large single phase inverter exporting (or significantly reducing import) on a three-phase connection could be breaching the phase balance limits which form part of the connection agreement with the utility. Of the connection standards I’ve seen, there must be less than 20A or 25A difference between any two phases, which maybe one of the reasons the new/draft AS4777 limits single phase inverters to 4.6kVA.

    Anyway, who knows how strictly the connection agreements are enforced, but why risk it.

    • disqus_3PLIicDhUu 4 years ago

      With the generator/ cables losses issue, this should only relate in a similar manner that domestic kVAr, does, which can be much worse and you don’t pay for that and a street transformer could have a variety of loads and PV’s across differing phases.

      .

      • Nathan M 4 years ago

        Sure. Most of the issues I raised only really become issues once you’re talking about a very big single phase PV system (say matching the demand on one phase). In that case, diversity in the distribution system won’t help much cause the imbalance is all on the customer side. Limiting single phase inverters to under 5kW is a good step IMO.

        • disqus_3PLIicDhUu 4 years ago

          For sure, that 5kW, single phase max, was a good idea, a few years ago we were installing a lot of 6kW single phase as 3 phase inverters were a rarity.

    • Boen Groothoff 2 years ago

      Hi Nathan,
      We are using 3-phase inverters in our tests with demand response to improve self-consumption. The three phase setup actually gives us other problems, since we cannot control the ditribution of PV-power over the three phases(this is always equal). As an example:
      Phase 1 = 1kW PV and 2 kW demand
      Phase 2 = 1kW PV and 0,5 kW demand
      Phase 3 = 1kW PV and 0,5 kW demand
      This gives a net import/export of 0 but in total 1 kW import and 1kW export. In the australian case this would mean 0,08 – 0,35 = -0,27ct for the consumer.

      We are trying to see whether we can solve this problem using batteries but haven’t found any with which we can control the power over the three phases individually.

      I you have any suggestions, they are very welcome!

  5. Adam Thomson 4 years ago

    wow watt a load of scare mungering crap

    • John Peterson 4 years ago

      Not sure if your trying to be funny with a pun (watt) or simply illiterate. If it was a joke, fine….average. If not then your response is an even bigger pile of crap, at least Finn explained in detail what was a real potential where as you announced to the world with all your credentials (burger flipper?) that it is BS…….care to elaborate and be critiqued yourself Adam?

      • Adam Thomson 4 years ago

        yeah i’m a licensed CEC grid install and design and have 13 years of metering experience in both utility and private metering . So yeah i actually know watt i’m on about (you can have that pun for free )

        • John Peterson 4 years ago

          Well no offense (well take it if you must) but a tradesman or techie at best certainly trumps an electrical engineer (CSIRO to boot), but forgive me I am only a ME but I can follow logic not to exclude human nature and capitalism but perhaps beyond sprouting a “qualification” of installation perhaps you could delve deeper into the actual machinations on how the meters are set up at a software/hardware level.

          But as a thought experiment:
          Perhaps you can explain then; if my 3 phase inverter is feeding, lets say, 1 kw on each of ABC phases while I run a 2kw hair drier on a any one of those single phases, is my meter recording the entire export vs the import instantaneously or is it racking up 2kw export while there is a
          net 1 kw import occurring instantaneously?

          Frankly I suspect it to be the later and as the power export price is a fraction of the import, even though I should be accruing no import feed amount I actually am of 1 kw while 2kw are being recorded as export, I actually do intend to data log this and compare against the bill cycle figures.

  6. ChrisEcoSouth 4 years ago

    I can attest that installers in SA were advised that SAPN 3-phase meters (then ETSA) are all configured to “average the export across the 3-phases”; ie correctly to nett the single-phase export against the 3-phase import. This started around 10 years ago, and many customers with 3-phase disc meters (and 44c FiT) got a rude awakening when an ETSA rolling upgrade gave them a 3-phase digital averaging meter!
    It’s ironic that these same averaging meters are now helping all those who only receive about 5c FiT.

    • John Peterson 4 years ago

      Hi Chris, are you describing a 3 phase import with a single phase export (ie single phase solar inverter)? How would this SA scenario work if you had 3 phase and a 3 phase solar inverter? If one phase was importing a greater load than the export on that phase, would you be charged the difference of meterage at import cost even though you might be feeding more PV energy than effectively consuming with the other two phases into the grid?

      • ChrisEcoSouth 4 years ago

        Hi John, my understanding is that this kind of meter does measure what is actually happening on the phases, but then does some internal calculation to ‘average/nett’ the import and export, across the phases. For the 3-phase example you give, I would say the meter would nett (and or average) the import against the export – which is nice if you are only getting 5c-odd for export.

  7. disqus_3PLIicDhUu 4 years ago

    Finn, you should mention that you can only use a three phase inverter if you have a 3 phase supply, many don’t, the client would be up for the costs, which can be considerable, for the 3 phase change.

    Blue phase?

    Normally when you pay for power with a 3 phase system, you pay for the total energy consumed, which obviously if you measure current per phase and apply a single phase calculation, appears more than the actual energy consumed and yes some of these electronic meters could be programmed for a variety of tricks.
    Sounds like they are treating the PV phase as a single phase supply, along with a two phase supply.
    Does their contract state net export energy, or net export PV phase energy?

    • gasdive 4 years ago

      Don’t worry. Finn has completely the wrong end of the stick. The polyphase meter you have on a three phase supply is physically incapable of metering the phases separately no matter what the programming. The people who look after the programming and maintenance of the meter are a different company to the retailers who make the money and the retailers who make the money have no access to the programming nor to the physical meter nor can they even tell if you have 3 phase or not. There’s absolutely nothing correct in this article. Try it yourself, ring your retailer and ask if you have 3 phase. It’s unlikely they’ll even understand the question. They simply have no input nor visibility of the number of phases or what they do or where or how they’re connected. They’ll no more know or care about that than they’ll know the colour of your cat. The only thing they’ll know is how much electricity you use and if you’re commercial or domestic use.

      If they really know what they’re doing they’ll transfer you to the the distributor who very likely will also not know if you have single or 3 phase. They don’t really know or care either. It’s a decision made by the ASP when they connect the property. If it was done in the last 5 years there *might* be records of their connection application. If you already have solar then the solar connection application will have the information but that’s the only way they’ll know.

      • JonathanMaddox 4 years ago

        So you’re saying that measuring exports on a single phase but imports on all three phases when a house has a three-phase supply is not a *deliberate* attempt by the utility to defraud the customer. Fair enough.

        But are you also claiming that this measurement isn’t inaccurate in the ways described in the article?

        • Guest 4 years ago

          That’s what I’m claiming. I’d be interested in any proof to the contrary that’s not in Tinfoil hat territory. I did say that they’re physically incapable of measuring the phases separately however that’s an over generalisation. It would be physically possible to program non disk type (many meters have an internal disk and an electronic display). However that’s not how they’re programmed. The rest I stand by. The retailers have no order that they can transmit to the DNSP to order a dodgy program. They don’t order the meters, the level 1 sparkie orders the meters (or occasionally they’re installed by the DNSP). All meters (not “most”) are bulk programmed. The field staff do not carry anything to reprogram the meters. Meters are never reprogrammed in the field. The DNSP would have no reason to implement such a program. It’s entirely absurd.

          disqus_3PLIicDhUu (whoever they are) says that the DNSP “obviously” knows how many phases you have. That’s rubbish. I’ve fielded literally *thousands* of requests from customers asking if they have multiple phases. I was able to guess that if they have 3 identical single phase meters then they probably have 3 phase, or the sparkie who installed it put in 3 meters for some reason (it may have been separate dwellings in the past for instance). If you’ve only got one single phase meter I can say you definitely don’t have 3 phase. If you’ve got a polyphase you may have 1, 2 or 3 phases. I can’t tell. There are *NO* records of who has 3 phase unless there has been a change in the last 10 years or so that required the sparkie to submit paperwork. If you ring faults (where I’ve also worked) and tell them that you’ve got part of the house working and part not, they will get you to check the switches and if that doesn’t restore supply they’ll get you to count the main fuses (there’s one per phase). There’s no “database” to check.

          This whole thing is like saying that cars are programmed to waste petrol and then lie to you about the odometer readings so you won’t notice and give false economy readings to the dash. Yeah, with some cars (not all) you could physically do it. To think that people are sneaking dodgy programs into your car to “rip you off” means you’ve given way to insanity.

        • gasdive 4 years ago

          That’s what I’m claiming. I’d be interested in any proof to the contrary that’s not in Tinfoil hat territory. I did say that they’re physically incapable of measuring the phases separately however that’s an over generalisation. It would be physically possible to program non disk type (many meters have an internal disk and an electronic display).
          However that’s not how they’re programmed. The rest I stand by. The retailers have no order that they can transmit to the LNSP to order a dodgy program. They don’t order the meters, the level 1 sparkie orders the meters (or occasionally they’re installed by the LNSP). All meters (not “most”) are bulk programmed. The field staff do not carry anything to reprogram the meters. Meters are never reprogrammed in the field. The LNSP would have no reason to implement such a program. It’s entirely
          absurd.

          disqus_3PLIicDhUu (whoever they are) says that the LNSP “obviously” knows how many phases you have. That’s rubbish. I’ve fielded literally *thousands* of requests from customers asking if they have multiple phases. I was able to guess that if they have 3 identical single phase meters then they probably have 3 phase, or the sparkie who installed it put in 3 meters for some reason (it may have been separate dwellings in the past for instance). If you’ve only got one single phase meter I can say you definitely don’t have 3 phase. If you’ve got a polyphase you may have 1, 2 or 3 phases. I can’t tell. There are *NO* records of who has 3 phase unless there has been a change in the last 10 years or so that required the sparkie to submit paperwork. If you ring faults (where I’ve also worked) and tell them that you’ve got part of the house working and part not, they will get you to check the switches and if that doesn’t restore supply they’ll get you to count the main fuses (there’s one per phase). There’s no “database” to check.

          This
          whole thing is like saying that cars are programmed to waste petrol and
          then lie to you about the odometer readings so you won’t notice and
          give false economy readings to the dash. Yeah, with some cars (not all)
          you could physically do it. To think that people are sneaking dodgy
          programs into your car to “rip you off” means you’ve given way to
          insanity.

          • disqus_3PLIicDhUu 4 years ago

            If you’d have read what I said properly, youre talking about your own case (state) you would have noticed I mentioned SA, my own state, which I am familiar with in depth, solar metering here is arranged as I indicated, the single network operator may receive bulk programmed solar meters, yes as I said, but meters sometimes need to be reprogrammed in the field for a variety of reasons-
            1.there are meters of the same type as the solar meters which were fitted to newer homes, that need to be reprogrammed for solar.
            2. There are meters with hot water tarrif, which is additional cost to client, where the client has gone gas and wants the bulk supplied meter reprogrammed deleting that tarrif.

            There are other reasons beyond this discussion.
            So please before you dis others, you need to be in charge of the facts.
            I’m a spark with over 30 years experience, got a Btech in electrical/electronic engineering, helping me understand complexity of meter operation, and worked in network construction and maintenance, so I know how this particular state operates.

            I don’t know to what level the ANMA works together to set tariffs, maybe Geoff Bragg, below might know, that’s management and above me and is to do with setting national metering and national standards in metering and tariff arrangements.
            All I do know is, by looking at the basic operation of a 3 phase electronic meter, it could well be possible to program it to read non standard ways.
            The question now is whether or not this unusual programmed meter is really out there, as Finn has already given information which is not factual..

      • disqus_3PLIicDhUu 4 years ago

        I don’t think you are quite right on the three phase electronic meter operation
        Each meter has separate internal phase current transformers and potential connections, this means a processor does the math to give total 3 phase energy use.
        It could well be possible to program a meter to read in the way suggested.
        Depends on the state, for the meter request procedure.
        In SA, the solar meter request goes from installer to the network operator and needs to indicate how many phases, though they obviously already have this information on the data base, then this goes to the retailer and back to the network operator for install.
        The meter is owned, for maintenance purposes by the network, they have programmers for field technicians to program meters via the infrared port’s, but most meters are pre programmed for bulk solar install.
        But it maybe possible somewhere for a retailer to produce a contract that could end up with this anomaly and confuse clients and request meters for this program, to be supplied, as otherwise the billing department should pick up this anomaly of bulk incorrectly programmed meters.

    • photohounds 4 years ago

      Incorrect text removed.
      .
      To expect this from 80 year old technology (or worse, allude to some “conspiracy”) is idiotic and as transparently greedy as the whiners claim only the power company is. I now see (below) that solar meters are smarter .. mea Culpa!
      .
      Of course the entire infrastructure got there free by magic and never requires maintenance. Also the solar people should determine how much they pay for this backup to be MAINTAINED for them …
      .
      Smart meters may be different, and I can’t see how they are programmed. I suspect the OP can’t either.

      • disqus_3PLIicDhUu 4 years ago

        This threads over 6 months old, but in reply, if a solar meter is an electronic meter, it doesn’t contain windings, it uses sensors and calculates the parameters, using a processor, it is programmed to read these parameters in different ways, so it’s possible to make the meter read in different ways, I know because I’ve programmed these meters.

        • photohounds 4 years ago

          Thank you, I wondered if my knowledge was a little old …

  8. John N Harden 4 years ago

    I contacted my solar installer and they chased
    the question of 3-phase residential power back through Energex (Richard Coutts,
    Solar Team) and the response was: “I spoke to one of our tech guys about
    this. Basically, from a metering point
    of view it doesn’t really matter whether the site has a 1-Phase or 3-Phase
    Inverter. The meter just measures the
    amount of electricity drawn from the network, and the amount of electricity
    that is exported back to the network from the solar system. Whether or not the
    customer would have been better off with a 3-Phase Inverter, is a matter
    between him and yourselves”.

    • Anne Ingleton 4 years ago

      All very confusing for the layperson………..
      As a retiree who is about to install solar, having gone through the minefield of countless sales pitches, I am at the last hurdle…………..the question of single or 3 phase inverter (we have 3 phase power to the house).
      If the cost toss-up between the two is relatively similar – a few hundred dollars on a 5kSW system – is the three phase inverter a “no-brainer”???
      David

      • Neil Burns 3 years ago

        David, I may be able to help you, but first, do you live in Queensland?

        • izak van der walt 2 years ago

          Hi Neil ,
          Live in brisbane and have a 3 phase zero return 15 kw system that is underperforming
          Can u help

    • Neil Burns 3 years ago

      Correct. However a single phase inverter connects to one phase only and the solar generated is utilised by the house circuits connected to that phase only. With a 3 phase inverter, the solar generated is divided equally across the three phases ie one third to each phase so all house circuits can utilise the output.

  9. glenny oc 4 years ago

    I was led to believe that the single phase inverter exports any surplus load to the RED cable or phase A on a 3 phase meter as that is dedicated much like the single phase meter. I have 3 phase but only the AC is running of the 3 and the 240v circuits are connected solely to the Red AFAIK.

    • Neil Burns 3 years ago

      It can be connected to the Red, Blue, or White. Preferably connect it to the phase which, before solar, was using the most daytime energy.

  10. photohounds 4 years ago

    If you only have a single phase inverter, how were the exports ever able to BE counted on the other phases in the first place?
    Simple answer: make sure you get a 3 phase inverter and stop inventing conspiracies.
    The (initially Howard) government (ie taxpayer funded) installation subsidies you all enjoyed are being paid for by people that are either renters or simply cannot afford solar.
    .
    You (mostly) also very conveniently ignore the fact that electricity infrastructure costs money plan, build and maintain. Also that it is not a power company responsibility to unbalance the load so that you can line your pockets. They invest to like THEIR OWN pockets.
    .
    But of course you shouldn’t contribute to that, right? Or at best should have a “say” in how much this is “worth”. Your workplace uses electricity, the companies that mage your solar hardware – or fix your car, or provide myriad other services to you also use electricity.
    .
    Yes they are somewhat greedy monopolistic businesses with Apple-like practices, but all I hear, here is: radio gaga and “me, me, me”.
    .
    Anyway now that the idiot carbon TAX is gone, the “load” is lessened – for everybody.

  11. A Nmkd Sarma 4 years ago

    Also what about consumers having 3phase conncetion and buying single phase solar inverters? What happens if any one of R,Y,B phase o/p of net meter is integrated with single phase power supplied by solar inverter? I have been told that power can’t b exported this way?!!!! DISCOMs globally have to lots of ground work to understand what is available in the market and how it can be integrated in the system as it’s next to impossible to get 3phase solar inverters below 5kVA range and many homes will have 2-3kVA range as load and so on….In India also we are facing these kind of issues and it’s a pain for consumers and suppliers as consumers find fault with suppliers.Is there any way that we can bring DISCOMs, vendors of various items of solar roof top systems and consumers and launch such policies which are mutually beneficial. Else it’s going to become a very big mess!

  12. Neil Burns 3 years ago

    After detailed analysis of several electricity retailer’s invoices and inverter output readings for a number of three phase supply/single phase inverter installations in SE Queensland, I have come to the conclusion that there are two different metering programs in use:

    1. Installations that have a feed-in tariff greater than the import tariff are programmed to use the single phase system ie the export is the excess energy generated over that consumed by one phase only, the one the inverter output is connected to. This amount displays as register 40. These are the older installations (before July 10, 2012) which have a mandated feed-in tariff of 44c/kWh minimum until July 1, 2028. The inverter output is best connected to the phase with the least daytime usage.

    2. Installations that have a feed-in tariff less than the import tariff generally have a single multiphase meter which is programmed to use the three phase aggregate system. The energy exported is the excess energy generated over that consumed by all three phases in total, even though the inverter output is connected to one phase only. These are installations after July 10, 2012 and which now have zero mandated feed-in tariff. However, retailers do offer varying feed-in tariffs up to 11c/kWh. It is irrelevant to which phase the inverter output is connected.

    Both of the above programs provide the greatest dollar benefit for the consumer which is the intention of the Queensland Government Solar Bonus Scheme. Both scenarios 1 & 2 could be inadvertantly misprogrammed by the meter installer resulting in a lesser benefit for the consumer.

    • Peter Elec 2 years ago

      Finally, someone who understands what is actually going on. The rest of you guys are bozo’s. The meters can be programmed for either Net metering or Gross metering. Since the feed in tarifs have dropped, there are some installations out there that should be re-programmed for Net metering – you need to contact your supplier if you have such an installation.

  13. Duncan 2 years ago

    What you are pointing out is totally logical, rather than a conspiracy.

    In the example that you give, the household is buying 1kW of someone else’s (potentially coal derived) electricity on each phase without solar, and selling 2.5kW of its own electricity on the phase that is plugged into the solar.

    Plugging a single phase inverter into a three phase house seems rather cavalier to me and I am not surprised that there are negative issues associated with this practice.

    If one would want to invest the cash in a 3 phase wired house, I don’t understand why one wouldn’t fork out for a 3 phase inverter.

  14. Stu Hearn 2 years ago

    and just make sure you do NOT have offpeak tariffs, you get no credits this way, hook all water heating and pool into full tariff Then time , or switch on to run only during the time the solar is generating near peak

  15. Stu Hearn 2 years ago

    bought a Lincoln vantage 400 welder/ genset, now i buy old 3 ph gear, get 17kva 3ph and 11 kva single, supplies neighbours when cyclones take out the grid

Comments are closed.

Get up to 3 quotes from pre-vetted solar (and battery) installers.