Net Metering: Why you can add a Sunny Boy Storage to a single or 3-phase PV system

by Daniel Chung (guest post), , 8 Comments

With the Sunny Boy Storage range of battery inverters, you can add battery storage to either a single phase or a three-phase PV system. Households in Australia are billed for their energy using net metering across all three phases of the grid. That means, the net energy purchased across all three-phases is what is billed, and it does not matter how energy is distributed across the phases.

Single Phase PV System and Sunny Boy Storage

In the animation below, the net power is always 0 kW no matter which phase the inverter is installed on or which phase the household loads are on. The Sunny Boy Storage can be installed on any of the available phases.

Three Phase PV system and Sunny Boy Storage

Similarly, the Sunny Boy Storage can be installed on any of the three phases at a site where there is a three-phase PV system. In the animation below, the home-owner is instantaneously billed 0 kW whether energy is supplied from the PV system or the Battery system.


The Sunny Boy Storage range is compatible with new or existing PV systems whether they are single or 3-phase. PV systems with non-SMA inverters may be accommodated.

Net metering ensures the single-phase Sunny Boy Storage can function on three-phase PV systems/sites. Note that for residential, grid-connected sites, there is no additional benefit of a three-phase battery inverter and is therefore an unnecessary cost add-on.

Check out the 2-minute video below:

How does net metering work for 3-phase sites?


  1. Avatar
    Les says:

    Net metering will mean there is no disadvantage in having the battery connected to a single phase in a 3 phase system, however what about battery back-up in a blackout? Can the Sunny Boy Storage be configured across all 3 phases for blackout protection?

    • Christiane Keim
      Christiane Keim says:

      Hello Les,

      the Sunny Boy Storage is not able to form a true 3-phase backup grid.
      However, you can still use the backup feature to supply one of the phases which includes the most vital loads like the refrigerator and lights.
      In certain regions, SMA may provide solutions for phase coupling during backup operation.
      Please contact your local SMA Service in case you need further support.

      Sunny regards

  2. Avatar
    Sven Carl says:

    Hi. The billing system in Denmark is exactly the same as in Australia.
    I would need a true 3-phase sunny boy storage system as you can not predict the use of power in the 3 phases. According to law we must install everything in order to have an equal power consumption in all 3 phases, but it will vary during the 24 hours. My inverter is STP 8000-10.

    • Christiane Keim
      Christiane Keim says:

      Hi Sven

      Your local SMA Service will be able to find a solution that satisfies your local grid requirements.
      For example, unbalanaced load limitation feature in the Sunny Boy Storage may be required by some grid operators.

      Best regards

  3. Avatar
    Alfred says:

    Good afternoon all,
    I have already a few weeks a problem with the first system above, we have STP10.0 and a SBS6.0 and 2 towers of BYD 11.00 kW. Now it seems that the energy from the batteries is going back into the grid. I will include a part of the email I received from the client. The installation is located near Lisbon, Portugal. Maybe you have an idea why or what happening here? Thank you already for your reaction.
    My dear Alfred

    I am sorry to be disturbing your rest on a Sunday, but the matter is serious.

    As you know from the beginning, we never understood the reason why the EDP metter gave very different results compared to those measured by the SMA system. At first we thought that the problem was the unidirectional EDP meter; we pay for a new counter but with the new bidirectional meter the problem remained.

    Consumptions measured by EDP are twice as high as those measured by SMA. EDP’s bills have not seen a significant decrease now with the solar system !……

    The solar system was very expensive, mainly due to the high cost of the batteries and charger .

    The conclusion of this new study points out that it is cheaper to use the system without batteries! …..

    As you can see from the table that I send you during 3 1/2 days, we disconnect the batteries and the SMA system meter reproduces the EDP meter, a fact that had never happened before.

    Today I reconnected the batteries and within 3 1/2 days I will send you a new record which, as I hope, will show different values between SMA / EDP meter.

    This appears to be a serious problem with the system for which a quick fix is needed before it becomes clear that the investment in batteries and chargers was a huge mistake.

    Please review the electrical connections, ask for SMA help, etc, etc, but please solve as soon as possible this intriguing mistery

    • Christiane Keim
      Christiane Keim says:

      Hello Alfred,

      Please contact our regional SMA Service Partner FF SOLAR ENERGIAS RENOVAVEIS, based in Aljezur.

      Sunnz regards

      • Avatar
        Alfred op den Brouw says:

        SMA ff Solar didn’t know this too, we just discover during the way that SMA is not informing well his installers. UP to today, SMA owners with a 3 phase inverter and a Sunny Boy Storage will all have to pay for there anergy when they use the batteries. SMA Iberica informed me different see email below from SMA Iberica :

        Respeito ás dúvidas que voce falou:
        Pode conectar duas baterias num SBS. Ele é um inversor de baterias “multistring”
        Pode ligar em qualquer uma das fases tal e como comentou, já que o medidor trifásico calcula e resta as fases. Exemplo se voce tiver: F1: 3 kW / F2: 0 kW / F3: -3 kW, o medidor vai medir 0 kW.


        J.G.H | SMA Ibérica|

        But this is not correct it seems now, here an email from the client after all research the client did. See part email of my client:

        I already have two EDP invoice.
        They based the bills to the figures the meter show !…..
        Any compensation system- direct reading and billing by the meter.

        From the 28th until sunday we were away from home and you can see the values:
        Screenshot 2021-05-03 at 09.49.10.png

        SMA registration 0,94 Kw and EDP meter 67 Kw !…….

        Last Saturday I lunch with a senior official at EDP, (recently retired) and he assured me that meters do not do any automatic compensation and that EDP does not. That was possible in the old meters, but with the new meters generation everything that the system injects is counted as an injection, everything that the network supplies is counted as a supply and there is no compensation system inside the meter.

        EDP today called me from EDP’s self-consumption department (Viana do Castelo) – an engineer confirmed to me that: “the problem is known and that if customers carefully check their consumption they will see that the battery solution does not always work well!…. “- he asked me right away if our battery charger was three-phase …, then he clarified that the meters do not make any compensation.

        So, after almost 3 months of misunderstanding how the system works, we must conclude:
        1. The system does not work within expectations.
        2. The economic gain from batteries is marginal. There is no reason to invest more than € 14 000 in a system that only provides 1/3 of the expected savings
        3. The current configuration does not work with the national energy supply standards of EDP and this fact CANNOT BE UNKNOWN BY SMA.
        4- The investment in batteries that, when everything works well is hardly justified, in this case then it is totally unjustified.
        5. Soon I will definitely disconnect the batteries and use only the direct consumption of the panels.
        6- I hope that in 15 days SMA and you will find a solution that works with EDP standards

        Alfred I believe that I have given all the help to make this installation a success, I have been understanding of the problems, I have been fully available to provide records and I will continue to do that, and I know that there have been efforts on your part, but the most recent conclusions let me to impose a different pace.

        On June 2, I will be away from home for several months and by that date I intend to have this dossier closed. We don`t have more time to fix this issue.
        I believe that it took us more than 3 months and that it is time to make decisions.
        The problem is identified and the SMA PROPOSED SOLUTION DID NOT RESULT.
        A perfect solution must be found quickly – SMA must clarify the problem with EDP ( not you neither me ) and if it is not working properly , SMA must correct it quickly.
        If this does not happen, I will definitely give up a battery solution.
        I await your news

        And as the client wants to know what SMA for solutions it can give, and why we received the wrong information, if we knew this before we never had installed this system!!

        Looking forward to hearing from SMA what your respond will be.

      • Christiane Keim
        Christiane Keim says:

        Hello Alfred,

        The Sales and Service Experts from SMA Iberica will get back to you regarding further support in that matter.

        Best regards

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