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  • Need help with Design of SMA based system.

    I am an EE and a few years ago I moved from the USA to the Island of Jamaica to take over a management job at a Data center our company runs.
    At this point I am thinking of staying for several more years as my wife is not keen on going back to the cold weather and likes it down here.

    One of the only annoying problems with this place is the Electric bills! They keep rising and rising with no end in sight. We recently got a 20% increase in our bills and we have been told that in another 3 months another is coming. At this point power costs .44 cents per KW. It is actually more expensive than Hawaii and is only going to go up higher as companies and the wealthy move to solar and LPG generators. Yes it is actually 40% cheaper to use a large LPG generator on a company than to use the utility service. MY current bill is averaging nearly $500 US a month!

    I kind of have my mind set on the SMA product line because several people over here have told me they work well and don't blow out under the brown outs and other issues we have over here. The problem is finding a competent designer. I have found one company that deals with SMA industrial inverters but the guy has little experience with home system that meets all my requirements.

    Requirements: (The voltage here is 115V / 230V at 50Hz.)
    The system must have batteries, I do have a small Honda Eu3000Si wired into another panel to help with the numerous power outages but we are told that they are about to put that next 20% hike onto peak hours which laughingly is between 6pm and 10pm.

    1) System must be able to shift power to batteries during peak time.
    2) System must work during a power outages, so I need a Micro-grid.
    3) Load sharing in the days between solar and batteries is also needed.

    I first thought of using all EU based 230V 50HZ SMA equipment and feeding the Sunny Boy output into the EU Sunny Islands AC1 input. Then taking the 230V form the Sunny Island and then sending the 230V into a Victron Autotransformer to get a split phase 115V 50Hz line voltage that would be tied to the grid.

    I finally got through to a tech at SMA and he said that I did not need to use a EU based Sunny Boy but I did need an EU based Sunny Island as the US one cannot do 50 HZ in a grid tie.

    I am starting to formulate a rough wiring diagram and would love some input.

    Here is the basic design. Please go easy on me, I am not a solar engineer, but the guy who does the industrial stuff can work with any diagram I hand him and he knows all the local electrical codes etc.

    BTW I am not looking to get off the grid completely, I just need to cut 50-60% of the power being consumed daily.
    12 panels will move to 24 after I see how it works out.

    Thanks for any help
    Solar System 120-240V_50HZ_Garth-SMA.jpg
    Last edited by robbyg; 04-19-2021, 01:55 AM.

  • #2
    What is your consumption in kWh/yr/month ?

    Lots of talk about inverters, what about the rest of the system design ? Siting, array orientation ?

    Future system expansion can be problematic as some things do not scale well.

    Why a 6kW inverter for a 4.4 kW array ?

    Download a dated but free PDF of "Solar Power Your Home for Dummies" or get a revised copy at Amazon/bookstores for ~ $25 U.S. With your background, the book will give you that basics of residential PV.

    Welcome to the neighborhood

    Comment


    • #3
      Originally posted by J.P.M. View Post
      What is your consumption in kWh/yr/month ?

      Lots of talk about inverters, what about the rest of the system design ? Siting, array orientation ?

      Future system expansion can be problematic as some things do not scale well.

      Why a 6kW inverter for a 4.4 kW array ?

      Download a dated but free PDF of "Solar Power Your Home for Dummies" or get a revised copy at Amazon/bookstores for ~ $25 U.S. With your background, the book will give you that basics of residential PV.

      Welcome to the neighborhood
      My consumption averages around 40-46KW per day. Typical bill will be between 1200 and 1450KW.
      The high level of Humidity plus the Concrete house construction makes electricity usage high, as insulation is poor and AC's and Fridges work a lot harder. It also does not help that I have a Salt Water Aquarium that uses a chiller and pumps etc. I have already optimized everything to the Max, I use to have a 1600KW bill but changing to Inverter AC's and more efficient equipment in the house and Aquarium has cut it down as low as it will go.

      6KW inverter is because I plan to do 24 panels if everything works out. I am having rails put in for all 24 but only installing 12 for the start.

      Thanks for the welcome
      Last edited by robbyg; 04-19-2021, 01:52 AM.

      Comment


      • #4
        The Sunny Island will work,for you, but is really geared for off-grid applications. I would suggest using the SMA storage system using a SunnyBoy inverter for controlling the array, a STS SunnyBoy Storage 6kW inverter for controlling the battery (usually the BYD 5/7/10kWh L-ion) and the ABU automatic backup unit that switches the load (up to 200A) over to the STS during outages. Not cheap. $10-12k wholesale as a bundle not including the SunnyBoy.

        SMA SBS+ABU+BYD diagram.pdf .
        Attached Files
        BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installed

        Comment


        • #5
          Originally posted by robbyg View Post

          My consumption averages around 40-46KW per day. Typical bill will be between 1200 and 1450KW.
          The high level of Humidity plus the Concrete house construction makes electricity usage high, as insulation is poor and AC's and Fridges work a lot harder. It also does not help that I have a Salt Water Aquarium that uses a chiller and pumps etc. I have already optimized everything to the Max, I use to have a 1600KW bill but changing to Inverter AC's and more efficient equipment in the house and Aquarium has cut it down as low as it will go.

          6KW inverter is because I plan to do 24 panels if everything works out. I am having rails put in for all 24 but only installing 12 for the start.

          Thanks for the welcome
          You're most welcome.

          Electrical consumption (energy) is measured in kWh, not kW. Power is measure in kW.

          Once you upsize to an 8.8 kW system, the 6 kW inverter that is perhaps oversized for a 4.4 kw system will be undersized.

          Off topic, but If I had a concrete house, I'd insulate the attic/crawl space/roof and insulate the exterior walls from the outside and kiss most of my HVAC loads goodbye.
          Last edited by J.P.M.; 04-19-2021, 12:26 PM.

          Comment


          • #6
            Originally posted by solarix View Post
            The Sunny Island will work,for you, but is really geared for off-grid applications. I would suggest using the SMA storage system using a SunnyBoy inverter for controlling the array, a STS SunnyBoy Storage 6kW inverter for controlling the battery (usually the BYD 5/7/10kWh L-ion) and the ABU automatic backup unit that switches the load (up to 200A) over to the STS during outages. Not cheap. $10-12k wholesale as a bundle not including the SunnyBoy.

            SMA SBS+ABU+BYD diagram.pdf .
            The problem with the Sunny boy storage is that I do not think that it does 50 cycle Electricity and I am not sure if it operates intelligently in a Microgrid setup.

            Comment


            • #7
              https://www.youtube.com/watch?v=7zoPu-uK4Xc
              get a sol ark 8k inverter. they do 50hz and can be configured as hybrid.

              Comment


              • #8
                Originally posted by khanh dam View Post
                https://www.youtube.com/watch?v=7zoPu-uK4Xc
                get a sol ark 8k inverter. they do 50hz and can be configured as hybrid.
                Thanks for the suggestion, I did consider it at one point but I kind of like SMA because I have heard so many good comments from long time owners. They seem to be pretty durable and flexible.

                The US Sunny boy also does 50hz and 60hz but it cannot work with the USA Sunny Island as the US version cannot do 50Hz even though you find literature that says it can. The European version of the Sunny Island is completely different beast, it has a lot of flexibility not only in the Frequency but in configuring it to do things that are not available in the US version due to regulations.

                I have sorted out the problem and it's a lot different solution than the diagram I posted. Overall it's more expensive solution but it does allow me to do several other neat tricks like schedule the load sharing and also auto start a generator and monitor it's fuel levels and use PV, Battery and Generators in an intelligent manor so that it gets through long power outages and also avoids using the grid power during peak times. I am not planning on using the Genny for peak hours, but it will be configured to come on in the event of a power outage and the batteries are getting too low.

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