Fronius IG Plus vs Primo 11.1/11.4

quique
quique Solar Expert Posts: 259 ✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
I have installed Fronius IG Plus A 11.1 with 4 strings of solar panels connected to them, interfacing to a 240VN uniphase grid.

Im looking over the Fronius Primo 11.4 but Im unsure if should use it.  The datasheet says it can either be used with 2 MPPTs or 1 MPPT.   According to their tool, with 2 MPPTs I can get:

5 strings of 9 panels each on MPP1 and 3 strings of 9 on MPP2.

If I combine the MPPTs (which I guess is a jumper or some other setting on the inverter itself) I can get:

5 strings of 8 panels.

What would the advantage of the separate MPPT be?  In case some strings are in a less than optimal location vs another set of strings?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    MPPT estimates the optimum solar array voltage.

    Mostly, this voltage varies with number of cells/panels in a string (your physical design) and the cell temperatures.

    This gives you the option to have different numbers of panels how many you can fit on s roof plane) and/or optimize the energy harvest with different roof plane (facing southeast vs southwest).

    As always, read the specifications & manuals closely. There maybe limitations in array configurations that a single 2 input gt inverter beyond the basic Voc/Vmp limitations.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Ethan Brush
    Ethan Brush Solar Expert Posts: 235 ✭✭
    #3
    The IG+A inverters are transformer based, while the primos are transformerless.  The latter will be lighter, safer, slightly more efficient, and easier to install.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Ethan Brush said:
    The IG+A inverters are transformer based, while the primos are transformerless.  The latter will be lighter, safer, slightly more efficient, and easier to install.
    How does removing a isolation transformer make the inverter "safer" ?   It won't crush all your toes if you drop it ?
    Powerfab top of pole PV mount | 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

    solar: http://tinyurl.com/LMR-Solar
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  • Ethan Brush
    Ethan Brush Solar Expert Posts: 235 ✭✭
    #5
    I believe that ungrounded, transformerless inverter systems can detect lower fault levels and do not have the ground fault "blind spot" issue that has caused fires (think bakersfield).
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