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Adding second array with Micro-Inverters

  • 25-05-2023 11:55am
    Registered Users Posts: 62 ✭✭

    Hi there,

    Not sure how random this query is but here goes.

    I have an existing solar array (16 panels approx 5.7KWs) and a string inverter (5KW) facing south.

    However, I would like to understand if I can add a completely separate array on a different orientation East/ West and rather than adding another String inverter I would like to utilize micro-inverters for those panels. 

    I'm aware of the ESBN imposed limit on inverters going forward and want to see if the Micro-inverter system would be able to be fed directly back to the consumer unit and be utilized by the house. 

    I already have batteries being charged from the solar array and also have an EV charger. 

    We have one EV at the moment with a second (large battery model) coming in 2024 hence i'm looking to increase my generation potential. 

    Is this a bonkers suggestion? Does anyone have recommendations for installers that would be in any way confident of supporting such a set up. I've already reached out to my previous installer but they have not come back yet.


  • Registered Users Posts: 2,504 ✭✭✭bullit_dodger

    Your easiest route forward is to increase the panels on your existing setup. This is the simplest. When I was getting my main installation in, I could only get 14 panels in, while adhering to the 50cm distances from the edges in order to get the SEAI grant. Fair enough.

    Once the grant was obtained, it's my dime and my roof, and by reducing the distances down to 35cm, I was able to fit in 3 more panels. Could this be case for you? Can you add to your existing instllation? If so it's only panels you have to fork out for.

    I also went the route of micro-inverters as a second installation - but something I installed myself. Not super hard as you can hook into an existing circuit, if the power output is low (<1-2Kw)

    The micro-inverters make telemetry interesting though. Your original installation will just see the house load disappearing as the micro-inverters take more of the load. So telemetry becomes a bit harder to understand, but the power is there and being used - just harder to "see" it.

  • Registered Users Posts: 6,941 ✭✭✭10-10-20

    Hi, I looked at this recently and this was my finding:

    ESBN's microinverter conditions specify that the installed capacity (in kVA) of all "grid connected" inverters is summed. This is specified in 1.3.3 of the document below. Additionally you can't subtract the storage capacity of any "grid connected" energy store, even if it's considered to be an ideal/infinite energy store (ie, continuously able to store all produced energy and offset the grid connected VA rating). Don't quote me word for word on that last phrase but I think that @slave1 had a better way of communicating that in a previous posting (which I can't find just now).

  • Registered Users Posts: 558 ✭✭✭idc

    You state the telemetry may be harder to understand, but that may depend on the inverter he has. The inverter I have is pretty cool in this exact scenario in that you can link an additional meter to the standalone inverter or microinverter and that is connected to the main inverter. The system then runs in a hybrid mode where it reports the generation from both. the main inverter can also concentrate on charging battery if the secondary inverter can cover the house load

  • Moderators, Sports Moderators Posts: 18,873 Mod ✭✭✭✭slave1

    our group understanding is ALL inverters are added together so in your case it would be 5kW inverter + every micro inverter, even battery inverters come into our interpretation of the esbnetworks energy capability so anyone with a 3kW Sofar ME3000 need to add that to existing string inverter

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  • Registered Users Posts: 1,009 ✭✭✭Mr Q

    That's true but how many ME3000's or similar are actually notified to the ESBN, the percentage would be tiny.

    I'm not saying they shouldn't be, but they're not.

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  • Registered Users Posts: 6,941 ✭✭✭10-10-20

    And two question come out of this:

    1. What if you have a primary inverter and secondary microinverters but the microinverters aren't on the approved list (Hoymiles or Enphase, etc), does that create a problem in relation to the NC6?
    2. What if you have a small count of microinverters and no approved primary inverter but yet you export excess energy to the grid, how is this managed by ESBN if these microgenerators aren't reported to them by the householder?

  • Registered Users Posts: 62 ✭✭builder22

    thanks @bullit_dodger for the response.

    My panels are LG360N1T-E6 ones (spec sheet attached), and as you're probably aware they are no longer being manufactured. I've been trying to source remaining stock but without a huge amount of success. I've been informed that additional panels should be from the same manufacturer, and be within +/- 15 watts from the original and of the same type i.e. N-Type. I'm pretty sure the voltage issue is correct but do additional panels need to be from the same manufacturer too?

  • Registered Users Posts: 1,009 ✭✭✭Mr Q

    I wouldn't worry about the brand if you are happy everything else will work in your string.

  • Registered Users Posts: 62 ✭✭builder22

    My set up is a GivEnergy 5KW Hybrid inverter with 16.2KWs of batteries.

  • Registered Users Posts: 62 ✭✭builder22

    I "think" based on what has been mentioned here the only way to have an increased size "Sum" of inverters would be go go down the NC7 route and there are no guarantees that this would be approved. Also i'm sure there would be added "professional fees" needed to make such an application on top of the 1000 fee to ESBN.

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  • Registered Users Posts: 6,941 ✭✭✭10-10-20

    Yes, that's the quandary as I see it. Either that or have an off-grid (isolated) circuit.

  • Registered Users Posts: 2,504 ✭✭✭bullit_dodger

    Probably the same supplier as myself (I've a GivEnergy solution too). Technically you don't have to get the EXACT panel as you have previously. If you get a new panel with higher wattage, I believe that they will downgrade themselves to work at the same as the existing ones.

    Ideally you want a panel with roughly the same characteristics (voltage, wattage, performance in low light) as your existing ones, but as long as it's roughly the same, it should work fine.

    Can't remember what you can oversize the 5Kw, but you should be able to go to 7Kwp without too much drama I would think. Confirm with supplier is best though.

  • Registered Users Posts: 62 ✭✭builder22

    Cool thanks @bullit_dodger. Do you think if i approached a panel wholesaler indicating the ideal panel type might they be able to source additional ones? If this is feasible does anyone have recommendations of good wholesalers to contact?

    I'll check on the max ability to push the inverter to.

  • Registered Users Posts: 62 ✭✭builder22

    The isolated circuit is an interesting notion - but wouldn't that negate the possibility of the additional panels feeding to the existing batteries and/or EV charger because they would be on another circuit and "mixing" the circuits would be a problem anyway? I'm not an electrician so if i'm mixing or misusing terminology please forgive me.

  • Registered Users Posts: 62 ✭✭builder22

    I'm sure i know the answer to this is "don't be so stupid" but if you could introduce an export limit to my GivEnergy inverter - I assume this does nothing to forgo the dilemma with having additional micro-inverters and therefore a total Inverter potential that exceeds the KW limit for a household.

  • Registered Users Posts: 21,792 ✭✭✭✭ELM327

    The reality is anyone installing microinverters is not declaring for NC6 anyway

  • Registered Users Posts: 2,504 ✭✭✭bullit_dodger

    Your question/statement is not stupid at all, but unfortunately ESBN don't care about export limits, or array orientations, etc. All they care about is the max rated output of the inverter. If you have multiple inverters, even if just battery inverters, then they are all added together to get the limit.

  • Registered Users Posts: 558 ✭✭✭idc

    Mine is AlphaESS so no idea if GivEnergy can do the same and have its dashboard take into account a second inverter.