Additional strings

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yodbar
yodbar Registered Users Posts: 2 ✭
in PV Installers Forum - NEC, Wiring, Installation #1
After combining 3 strings in a combiner box is it ok to put all that power on just one line into the inverter. To give some history, I have a solar edge 10kw inverter and 2 strings of 18 for a total of 36 panels at 280 watts a piece. Checking with solar edge they say I can go up to a max of 12.25 kw and it won't be a problem. I bought 7 panels at 330 and took 3 panels off each of the 2 existing strings and combined them in a combiner box. My question is can I now run the single existing wire that has been combined from the 3 strings and run it into 1 of the 2 existing openings? 
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,046 ✭✭✭✭✭
    #2
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    Do you have the Solar Edge optimizers connected? A combiner box is for raw DC voltage from the panels. Optimizers have a proprietary trunk cable which as far as I know you wouldn't be using a combiner box on. Maybe things have changed with Solar edge?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    edited October 2022 #3
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    Likely, You don't give specs for the panels, but in series they will have the same amperage, just the voltage increases. So check the current coming from 1 panel and add it to the the other strings and check the wire gauge and see if it meets the NEC code for ampacity of that gauge wire;

    What is wire ampacity and how do you find ampacity rating

    BTW - yodbar said:
     I bought 7 panels at 330 and took 3 panels off each of the 2 existing strings and combined them in a combiner box. 
    This might not be a good idea. The strings likely should be similar size and the voltage 30% above the line voltage you are feeding after losses.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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