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Unequal number of panels in strings?

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  • Unequal number of panels in strings?

    We have twenty 170-watt panels connected in series in two 10-panel strings. The two strings are connected to a Fronius inverter. One of the panels' glass covers has shattered (for unknown reasons). Can I simply remove it, and run one string with 10 panels and the other with 9? Do two-string inverters require that the voltage from each string be equal, or are these types of grid-tied inverters capable of handling strings of differing voltages?

  • #2
    The question is,...
    Does your inverter have 2 MPPT inputs, or do the solar strings go into one set of terminals ?

    And if it does have 2 inputs, will a shortened string have enough voltage to properly run ?
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



    • #3
      You should be fine with unequal panel counts. The Fronius will treat the strings independently.

      It would be best to read the Fronius spec sheet to be sure that 9 panel output voltage fits within the window of the Fronius, but if it is like modern Fronius inverters, you'll be fine.
      7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV


      • #4
        Thanks for the answers. The Fronius was installed in 2014 and it will work with the 9 panel output voltage.