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2nd Inverter - Adding a 2nd building to existing solar

  • 04-12-2024 01:44PM
    #1
    Registered Users, Registered Users 2 Posts: 100 ✭✭


    Hi All, I asked this question on another thread, and then realised the thread is 2 years old! so apologies if it repeated here. Thought maybe its best to start a new thread.

    2 inverters seperate db.jpg

    I'm currently running a Sunsynk 5kw with 6k of panels attached to a 6.4kwh battery. This is powering one house and selling excess back to grid.

    I would like to also power a separate building. Ideally separately and also sell excess to grid.

    I am thinking of getting another SS 5k , 13kwh if Seplos battery and 7kw of panels for the 2nd building.

    Is it possible to run both these set ups and export excess?

    There is only one ESB connection to the property.

    What happens if one inverter is importing while the other is exporting?

    Thank you all

    p.s. sorry for the 1st few mixed up replies, i tried to reply with quotes but i didnt get the hang of it for a while!

    Post edited by daesal on


Comments

  • Registered Users, Registered Users 2, Paid Member Posts: 9,237 ✭✭✭10-10-20


    No as you're limited by the export limitation on the main meter of 25A (~5.7kW) on a standard connection under the standard connection. You could request an upgraded export limit of 7kW, but that's still not going to support your dual 5kW intent.



  • Moderators, Home & Garden Moderators Posts: 7,102 Mod ✭✭✭✭graememk


    Assuming you got the ESBN clearance,

    This is a scenario where you need communication between the inverters, which the sunsynk does support - but I'm not even sure it supports multiple separate batteries though. I think there is wiring diagrams in the manual for it.



  • Moderators, Sports Moderators Posts: 18,289 Mod ✭✭✭✭slave1


    Is a single large Inverter an easier option (NC7 territory in any case)

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  • Registered Users, Registered Users 2 Posts: 19,263 ✭✭✭✭ELM327


    I would have all the batteries and the main inverter (a hybrid) as the only grid connected one, and then put the second array as a string only inverter, the main inverter can then use the energy as it sees (either export or charge batteries etc)



  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Thank you for the reply. With paralleling the inverters would need comms for sure.

    Unfortunately the SS manual , and installers guide don't really touch on joining without parelling, which would not work in this scenerio . Because they are so far apart from each other the comms cable would not work. But also I am trying to find a solution where both set ups are almost independent except for the grid feed in. i.e.not paralleling.

    Would there be an issue with one feeding in while the other was drawing?

    or would a correctly placed CT coil on each sub db board solve this?

    P.S. You're right about the batteries too, with paralleling the SS does support multiple separate batteries, but it wouldnt support multiple different spec batteries



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  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Hi Elm, Thanks for your reply:

    I would have all the batteries and the main inverter (a hybrid) as the only grid connected one, and then put the second array as a string only inverter, the main inverter can then use the energy as it sees (either export or charge batteries etc)



  • Registered Users, Registered Users 2 Posts: 6 D_Eng


    Has anyone gone this route, but used MPPT charge controllers (dc-coupled to battery connected to primary hybrid inverter) instead of a second string inverter? Could keep you on the right side of the NC6/NC7.



  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Thank you. Defiantly a solution if I was not keeping the 2 buildings separate . In this case each building needs its own battery supply and inverter. I am wondering if the 2 sub DB boards in the diagram would be able to feed/pull from the main DB and meter at the same time with correctly placed CT coils?



  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Thank you, yes it definitely would be!

    If I wasn't trying to keep the 2 buildings separate. With each having its own set up.



  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Thank you. Assuming ESBN clearance.

    Would the set up work? With correctly placed CT coils on the 2 sub DB boards ?

    Would this prevent one set up feeding while the other was drawing?



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  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Thank you. Defiantly a solution if I was not keeping the 2 buildings separate . In this case each building needs its own battery supply and inverter. I am wondering if the 2 sub DB boards in the diagram would be able to feed/pull from the main DB and meter at the same time with correctly placed CT coils?



  • Registered Users, Registered Users 2 Posts: 2,646 ✭✭✭SD_DRACULA


    I assume this is some sort of granny flat situation.

    A neighbour of mine got pv and batteries and he was wondering that if he exports will the 2nd building capture the export, it doesn't.

    It's about where you place the CT, in his situation on the cable feeding his board but not on the one going to the second board.

    Single esb connection so going by that example maybe it is possible, essentially DON'T put the CTs on the main incoming cable.



  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    I was thinking 2 CT clamps.

    One for each Sub DB . Connected between the Sub boards and their respective Inverter.



  • Moderators, Home & Garden Moderators Posts: 7,102 Mod ✭✭✭✭graememk


    In that case it will only take Care of any load after the CT, eg the sub boards only. it won't cover any load on the main CU.



  • Registered Users, Registered Users 2 Posts: 100 ✭✭daesal


    Yes exactly. So the main CU splits directly to 2 different sub DB'S (one for each building) with all loads coming off the sub DB'S .

    Sorry , the sketch is very basic and doesn't make that clear!



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