Wiring Question: 600W Grid Tie System

Hi everyone, I bought six 100W Solar panels and one 22-65V, 1000W Grid Tie inverter. I'm looking for guidance on how to wire the panels properly before starting the job.
It says that the panels are rated at 5.72 Amps and 17.9 Volts each.
I'm having trouble figuring out how to wire them so that I have about 53 Volts going into the inverter. 
Would appreciate some guidance on this. Thanks in advance.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,680 admin
    Welcome to the forum Bryan,

    If you have a link for the GT Inverter--It would be nice to confirm the specifications.

    And a link to the solar panels you have (or the Voc/Vmp/Ioc/Imp ratings and the series fuse protection).

    And, roughly, where are you located and what is your minimum temperature.

    Vmp and Voc rise as temperatures fall... So the actual array configuration is location/temperature dependent (as well as double checking the specifications for the GT inverter).

    You have two configuration options... The first is 2 series * 3 parallel panels. That should work 100% of the time. However, with 3 strings in parallel, you should have a combiner box with fuses/breaker rated for the "series protection fuse" listed in the solar panel specifications. The series fuse/breaker is there to prevent a short circuit in one panel from being fed too much current by the other two parallel strings.

    You also do not want Vmp-array-hot to be too low and not start/run the GT Inverter on hot summer days.

    If you are in the Florida area, you may have pretty warm winter temperatures, which means that Voc-cold will not rise that much (Voc/Vmp/etc. are at 75F/25C). For very cold regions, the Voc rating can rise and exceed the Vinput rating of the GT inverter on very cold mornings.

    If you can run 3 series x 2 parallel strings--You do not need the "combiner box" (saves costs on box and fuses/breakers). You do not want Voc-array-cold to exceed Vinput rating of GT inverter.

    In general, you would prefer the 3sx2p configuration. Higher Vmp-array voltage allows you to use smaller AWG wiring (save copper wiring costs, as well as the cost of combiner box assembly). 

    In North America, the GT inverter output should be wired to its own dedicated circuit (120 or 240 VAC--Depending on your GT inverter's output rating). For safety reasons, you should not share a single branch circuit with loads and GT inverter output(s)... In some failure conditions, you can overload the branch circuit wiring and smoke your wiring/cause a fire.

    Lastly--You want the panels to be securely mounted to the rack/structure/etc. so that hurricane winds do not blow them free... And if you are in a region with lots of lightning, you want to ensure the array is probably grounded (short/straight shot from solar panel frames/racking to ground rod with "soft rounded" wire run corners--typically 6 AWG minimum.

    Also, you would want SPDs (surge protection devices) on the GT Inverter solar panel input, and on the GT Inverter output or in the main panel to dump lightning energy to earth ground, and not to your solar array/GT inverter/House wiring...

    https://www.solar-electric.com/search/?q=spd+midnite 

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,274 ✭✭✭✭✭
    You need to look at the Voc spec on the panels, and I suspect it will be about 22V.  So realistically, (unless you live in the warm tropics) you can only wire 2 panels in series = 35.8 into the inverter.   Three strings in parallel will require a combiner box with overload protection for 3 solar channels, using breakers no larger than the ""Series Fuse Spec" on the PV panel label.

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