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Three String PV array options

  • 25-02-2021 1:14pm
    #1
    Moderators, Sports Moderators Posts: 16,073 Mod ✭✭✭✭ slave1


    I see DrPhil and I and quite possible a few others are looking at a third string of PV panels.
    I thought it would be an idea to have a separate thread as otherwise could get buried in the Tips thread when it deserves its own thread.

    For me I've 10 410w panels on one string and 8 of same on second string, this covers my front and back roof and maxes out my 6kW Solis MPPT inverter.

    I am toying with the idea of putting up to 3kWp on my back fence in order to top up my Winter production as my 3.3 string does not get direct sunlight and my 4.1 string is caught by tree shading.
    My back fence is quite high at around 15feet and my idea is to place the panels vertical, however with sun movements different part of the string will be in various shades throughout the day.
    I was thinking dual micro inverters that would handle two panels but these add up and if I put up say, 10 panels then that would be 5 micro inverters.
    Other option would be a 4kW dual MPPT inverter but I think the shading would again catch me out.

    I would also like to monitor the production, with a second Solis inverter I would just add to my existing Solis app so easy peasy, not so sure about the micro inverters though?

    Any tips advice?
    DrPhil, you could throw your thoughts up here too if you don't mind as v similar to mine


Comments

  • Registered Users Posts: 409 ✭✭ phester28


    There are 4 input micro inverters from a main supplier in Ireland. Each input would be individual mppt. Also avaliable in double input


  • Moderators, Sports Moderators Posts: 16,073 Mod ✭✭✭✭ slave1


    I keep changing my mind about micro inverters and a dedicated dual MPPT inverter.
    I need to keep in mind to manage my export limit as I'll (on paper) have a ~11kWp system, I'm not sure if a series of micro inverters will talk to my Solis inverter and somehow limit the export (should it occur) or even whether another Solis inverter will either....
    I also need to figure out the mounting as I want to do it myself.


  • Registered Users Posts: 125 ✭✭ Ballylad


    I was also thinking of adding a third string of panels on ground ballast.
    I currently have 18 panels (3 rows of 6, 290w, 5kw) going to a 4kw SMA invertor.
    I have a 2 EV household with Zappi charger, a heqt pump that runs at 5.3kw max mostly at night rate and couple of hours during day, granny flat, one EV mostly at home plugged into zappi for excess electricity. All panels facing SSW, no shading. No grant support will be requested.
    To increases PV production throughout year,
    I was hoping to get an extra 14 390w panels to give a total of 10.5kw output.
    A 8.5kw fronius dual MPPT inverter with export limitation would be preferred inverter.
    How do I add these strings to the inverter, no knowledge of this.
    Would I get away with that inverter for 6kw export limit, cant see I would have that excess going to grid in first place.
    Any suggestions/ information appreciated.


  • Registered Users Posts: 125 ✭✭ Ballylad


    Ballylad wrote: »
    I was also thinking of adding a third string of panels on ground ballast.
    I currently have 18 panels (3 rows of 6, 290w, 5kw) going to a 4kw SMA invertor.
    I have a 2 EV household with Zappi charger, a heqt pump that runs at 5.3kw max mostly at night rate and couple of hours during day, granny flat, one EV mostly at home plugged into zappi for excess electricity. All panels facing SSW, no shading. No grant support will be requested.
    To increases PV production throughout year,
    I was hoping to get an extra 14 390w panels to give a total of 10.5kw output.
    A 8.5kw fronius dual MPPT inverter with export limitation would be preferred inverter.
    How do I add these strings to the inverter, no knowledge of this.
    Would I get away with that inverter for 6kw export limit, cant see I would have that excess going to grid in first place.
    Any suggestions/ information appreciated.

    Just realised, the voltage would be exceeded with this many panels and placing some of them in parallel would be no better?
    probably better off with two fronius inverters, 4kw for 5kw array already there and 5kw for the new ground mounted array, both can use the one export limitation software?


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    itshappening.gif, third array has been ordered!


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  • Registered Users Posts: 2,789 ✭✭✭ irishchris


    mp3guy wrote: »
    itshappening.gif, third array has been ordered!

    What size third array have you gone with?

    Had anyone run into problems with the Esb when submitting nc6 form? Are the Esb particular about the size of inverters going above 6kw?


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    irishchris wrote: »
    What size third array have you gone with?

    Had anyone run into problems with the Esb when submitting nc6 form? Are the Esb particular about the size of inverters going above 6kw?

    Adding another 5.76kW. My max inverter output will still be 11kW between two inverters (leveraging DC oversizing). But both actually support export limiting, one of them entirely shuts down if it loses meter reading so it'll be doubly failsafe if a fault occurs.

    Didn't have any issues with my initial 9.2kW, see my posts starting here https://www.boards.ie/vbulletin/showthread.php?p=116323839#post116323839.


  • Registered Users Posts: 2,789 ✭✭✭ irishchris


    mp3guy wrote: »
    Adding another 5.76kW. My max inverter output will still be 11kW between two inverters (leveraging DC oversizing). But both actually support export limiting, one of them entirely shuts down if it loses meter reading so it'll be doubly failsafe if a fault occurs.

    Didn't have any issues with my initial 9.2kW, see my posts starting here https://www.boards.ie/vbulletin/showthread.php?p=116323839#post116323839.

    Cheers, I see the initial post now alright where you said the Esb had in writing said there's was no issue. Had you emailed them and if so what email did you use as tried contacting esb networks but no reply from them here


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    irishchris wrote: »
    Cheers, I see the initial post now alright where you said the Esb had in writing said there's was no issue. Had you emailed them and if so what email did you use as tried contacting esb networks but no reply from them here

    It was my installer that emailed the Network Services Bureau, might be why they got a response rather than an individual.


  • Registered Users Posts: 125 ✭✭ Ballylad


    irishchris wrote: »
    Cheers, I see the initial post now alright where you said the Esb had in writing said there's was no issue. Had you emailed them and if so what email did you use as tried contacting esb networks but no reply from them here

    This is my ground mount foundation, sun fixings frame on top


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  • Registered Users Posts: 125 ✭✭ Ballylad


    irishchris wrote: »
    Cheers, I see the initial post now alright where you said the Esb had in writing said there's was no issue. Had you emailed them and if so what email did you use as tried contacting esb networks but no reply from them here

    This is my ground mount foundation, sun fixings frame on top eventually


  • Registered Users Posts: 125 ✭✭ Ballylad


    irishchris wrote: »
    Cheers, I see the initial post now alright where you said the Esb had in writing said there's was no issue. Had you emailed them and if so what email did you use as tried contacting esb networks but no reply from them here

    This is my ground mount foundation, sun fixings frame on top eventually


  • Registered Users Posts: 125 ✭✭ Ballylad


    mp3guy wrote: »
    Adding another 5.76kW. My max inverter output will still be 11kW between two inverters (leveraging DC oversizing). But both actually support export limiting, one of them entirely shuts down if it loses meter reading so it'll be doubly failsafe if a fault occurs.

    Didn't have any issues with my initial 9.2kW, see my posts starting here https://www.boards.ie/vbulletin/showthread.php?p=116323839#post116323839.

    Seems like a great set up, what inverters did you originally use?


  • Moderators, Sports Moderators Posts: 16,073 Mod ✭✭✭✭ slave1


    mp3guy wrote: »
    itshappening.gif, third array has been ordered!

    Jazus, given your massive production currently why go even higher?
    I know you have an EV but still??

    Fair dues though, will watch with interest


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    Ballylad wrote: »
    Seems like a great set up, what inverters did you originally use?

    SolaX X1-Hybrid 5kW and SolaX X1-Boost 4.2kW.
    slave1 wrote: »
    Jazus, given your massive production currently why go even higher?
    I know you have an EV but still??

    Fair dues though, will watch with interest

    I'm not too concerned about peak, but more about the bottom line. We are currently a 1 EV household with OFCH. In the next few years that'll change to 2 EVs and a heatpump, which should soak up most of that energy.


  • Registered Users Posts: 125 ✭✭ Ballylad


    mp3guy wrote: »
    SolaX X1-Hybrid 5kW and SolaX X1-Boost 4.2kW.



    I'm not too concerned about peak, but more about the bottom line. We are currently a 1 EV household with OFCH. In the next few years that'll change to 2 EVs and a heatpump, which should soak up most of that energy.

    The issue with heat pump is the large current they draw, unless you have a well insulated A rated house, my 5kw array won’t cover my heat pump 5.3kw so have to run it at night rate, I’d say your 11kw array would cover a heat pump but what will it produce in winter when heat pump works the hardest


  • Moderators, Sports Moderators Posts: 16,073 Mod ✭✭✭✭ slave1


    Oh okay, I think differently, over the years I’ve insulated the house to the hilt, now all it takes to heat it is half a bucket of coal a day in Winter and with that’s with bedroom windows open every night of the year. B1 BER. Can't see a heat pump adding any value or savings in this scenario.


  • Registered Users Posts: 125 ✭✭ Ballylad


    slave1 wrote: »
    Oh okay, I think differently, over the years I’ve insulated the house to the hilt, now all it takes to heat it is half a bucket of coal a day in Winter and with that’s with bedroom windows open every night of the year. B1 BER. Can't see a heat pump adding any value or savings in this scenario.
    If it’s B1 rated, you won’t need a large heat pump so will be extremely efficient, underfloor heating would be a plus, mine is 12 years old, I’ve a 3400sq ft house extra insulation added but there is only so much you can do with 12 year old house.


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