Wire size for sure shine inverter ?

Thom
Thom Solar Expert Posts: 196 ✭✭✭
in Off Grid Solar & Battery Systems #1
Is #6 NM-B ok for inverter to battery ? The batteries are less then 4 feet from inverter.

Thanks
Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat 
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #2
    Re: Wire size for sure shine inverter ?

    What size inverter is it (and model number would help).
    And will this still be on 12v as your sig shows?
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • Thom
    Thom Solar Expert Posts: 196 ✭✭✭
    #3
    Re: Wire size for sure shine inverter ?

    SureSine Inverter-300W, 115V 60Hz . It is a 12v system
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat 
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #4
    Re: Wire size for sure shine inverter ?

    How you can work this out: (6awg is about 13mm2).

    First you need the peak amps. Dont need to get carried away with surge or drop out voltages.
    I= P/V/efficiency

    Resistance of the cable (using metric units)
    R (ohms) = 2 * cable length (m) * resistivity of Cu (0.000000017 ohm.m) / cable area (mm2) * 1000 * 1000

    Then lastly the voltage drop is:
    Vdrop= I * R

    So for you thats:
    I= 300W/12v/0.88 eff = 28.4A
    R= 2* 1.2m * 0.000000017 / 13mm2 * 1000 * 1000 = 0.00313 ohms
    Vdrop= 28.4A * 0.00313 ohms = 0.09V

    Which is 0.09/12 = 0.7%, which is just dandy.

    If you use a online calculator like http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=1.296&voltage=12&phase=dc&noofconductor=1&distance=4&distanceunit=feet&amperes=24&x=47&y=14

    note that they want the one way distance, whereas in the formulas above ive used 8 feet.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • Thom
    Thom Solar Expert Posts: 196 ✭✭✭
    #5
    Re: Wire size for sure shine inverter ?

    Thanks for the help
    I got my NZ wool sox on :0)

    Thom
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat 
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  • cupcake
    cupcake Solar Expert Posts: 254 ✭✭✭
    #6
    Re: Wire size for sure shine inverter ?
    Thom wrote: »
    Is #6 NM-B ok for inverter to battery ? The batteries are less then 4 feet from inverter.

    Thanks

    I use this inverter and use 6awg going about 4 feet to the batteries...

    --cakie
    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Wire size for sure shine inverter ?

    In continuous use the Sureshine draws about 30 Amps maximum (30 * 12 = 360 Watts). Therefor the minimum wire size you could use would be 10 AWG. In 4 feet the V-drop would be about 2%.
    6 AWG will never show a problem at that short a distance: V-drop <1%. :D
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