Wire size from panels

System
System Posts: 2,511 admin
in PV Installers Forum - NEC, Wiring, Installation #1
Hi
Have 10 Evergreen 200 watt panels, the run is appox 60 feet to Evergreen Ctrl.

To achieve 3-5% voltage loss what size wire should be used, i have run some rough numbers and come up with 00. Would like some other opinions. Is this really needed? Someone told me that a pair of #8's would do it but it seems to me that it would be very ineffcient!

Thanks
Jerimiah
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #2
    Re: Wire size from panels

    What is the make/model of Charge Controller?

    What is the voltage of the battery bank (and AH rating if handy)?

    What is the Vmp/Imp of the Evergreen panels?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
    #3
    Re: Wire size from panels

    Use this handy calculator: http://www.csgnetwork.com/voltagedropcalc.html

    If you are wiring them in parallel for 12V system, then to get 5% loss you need 4/0 AWG.
    With 150V max input MPPT charge controller you can get 4.2% wire loss using only 10 AWG wire, if you wire your panels for 90 Vmp (5 panels in series x 2, assuming panels are 18Vmp each). MPPT controller loss is around 2 - 5% depending on output voltage.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: Wire size from panels
    jerimiah wrote: »
    Hi
    Have 10 Evergreen 200 watt panels, the run is appox 60 feet to Evergreen Ctrl.

    To achieve 3-5% voltage loss what size wire should be used, i have run some rough numbers and come up with 00. Would like some other opinions. Is this really needed? Someone told me that a pair of #8's would do it but it seems to me that it would be very ineffcient!

    Thanks
    Jerimiah

    is this for a gt system or a battery backed system? if for a gt system the pvs are wired in series and as such the current is low and the wire requirement will also be low.
    now in a battery backed system there will be more current to go along with a lower voltage and depending on how it is arranged can help us determine just what is sufficient. most would recommend staying with a 2-3% drop as solar power is more expensive to be losing to being cheap on the wires. also, for battery backed systems, it is recommended that losses between the controller and batteries be kept well under 1% as many controllers will otherwise think the batteries are at a higher voltage than they actually are and thus not reach a full charge.
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