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Adding an additional Inverter without panels

  • 16-02-2023 5:56pm
    Registered Users Posts: 1,123 ✭✭✭

    I have a 16 panel system with two separate linked 3kw GoodWe GW3000-XS Inverters (6KW in total). There is 8 panels linked to each 3kw inverter. Can I add a third 3Kw Goodwe inverter? I don't plan to add any additional panels yet but will add another string of panels to this inverter in the future. I am just wondering will the extra inverter on its own linked to my other two increase my production capacity from 6kw to 9kw in the short term on the existing panels? I'm assuming they will work in conjunction with each other but I could be wrong? Also would this be an issue with the ESB as I am currently on a single phase connection and an additional inverter will bring the size to 9kw?


  • Registered Users Posts: 4,851 ✭✭✭paulbok

    What size panels (Wh) are they and what direction do they face?

    Even at 420Wh each and all facing south with a good roof pitch, you will only be pushing more that 6kWh into the 2 inverters for a couple of hours on the sunniest days of the summer. I have 6.84kW of panels facing south on a 6kW inverter and haven't lost out on too much production when the inverter clips anything over 6kW. when this would occur, you are likely to be exporting it anyway, so unless you are on a smart meter with measures FIT exports it won't benefit you either.

    It wouldn't make financial sense to add another inverter without panels to go with them. You might be better looking into adding more panels first to your existing setup, string limitations excepted, and max the 2 existing inverters out more during the year, especially if you have a mixed aspect setup. You will have more clipping (inverter restriction) on the sunny summer days, but will have more production available to use this time of the year for example, when the panels aren't really producing what they are rated for.

    Those with more experience on setups can answer better but I think you would have to restrict the exports off the 3rd inverter (when you have panels to provide juice to go with it) when you are generating/ exporting over 6kWh if you are on the standard NC6 connection.

  • Registered Users Posts: 3,145 ✭✭✭irishchris

    Problem is most inverters are dc powered so will need a certain amount of panels connected to bring it up to the startup voltage required to turn on

  • Registered Users Posts: 2,330 ✭✭✭bullit_dodger

    Could just add panels with micro-inverters? In theory you would be breaking the NC6 6Kw limit, but that might not be an actual issue if your panels aspects didn't allow 6Kw to be broken. Yes, before someone mentions it, technically the aspects doesn't actually matter - you'd still be non-compliant, but just saying.

    E.g. Get two panels and use one of these....

    Hoymiles HM-600 600w Microinverter (

    and then add more panels as you see fit.

  • Registered Users Posts: 20,948 ✭✭✭✭ELM327

    NC6 limitation is on export and not on the total connected capacity. Once your setup is not exporting more than 6kW then you are in compliance with NC6

  • Moderators, Education Moderators, Home & Garden Moderators Posts: 8,025 Mod ✭✭✭✭Jonathan

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  • Registered Users Posts: 164 ✭✭oaklands

    Seems to say inverter capacity up to 6kW for single phase & 11kW for 3 phase

    All related info available via:

  • Moderators, Sports Moderators Posts: 18,428 Mod ✭✭✭✭slave1

    It's capacity to generate not to export, this was covered quite some time back so I can't remember when and on what thread

  • Registered Users Posts: 20,948 ✭✭✭✭ELM327

    It would be helpful if there were a link , most times I've seen this discussed here or elsewhere it's pretty much always mentioned that the NC6 is export not production limited.

  • Registered Users Posts: 164 ✭✭oaklands

    It is explained very well (in my opinion) via the link posted above => click on Step 1 for the pdf.

    (PS: I also noticed that there are at least 2 versions of the NC6 form on the ESBN site)

  • Registered Users Posts: 2,330 ✭✭✭bullit_dodger

    I think this is the relevent section.....

    1.3.3 Installed Capacity

    ➢ Where the Energy Source Capacity is connected through, and therefore limited by, an inverter then the Installed Capacity shall be deemed to be the inverter rating (in kVA), as shown in Figure 1. For the avoidance of doubt the rating of the inverter shall be taken as the continuous steady state rating of the equipment and may not exceed 25 A (c. 6 kVA) single phase or 16 A (c.11 kVA) three phase. 3 This equates to approximately 6 kVA 4 This equates to approximately 11 kVA Copyright © 2021 ESB Page 5 of 19 This document is uncontrolled when printed. Check its validity before use.

    For inverter connected generation connected through multiple inverters, the Installed Capacity shall be the sum of the inverter ratings directly exporting through the DSO network connection point, as shown in Figure 2.

    ➢ Where there is no inverter the Installed Capacity shall be deemed to be the Energy Source Capacity, as shown in Figure 3.



    Basically this is in alignment which what I always suspected that it's the sum of the inverters, not the panels themselves. In theory many of us are breaking that rule.....however, with my aspects, I can't actually export more than 6Kw. But yeah, technically I'm in breach of it myself.

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