Wiring Size etc.

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Chris11
Chris11 Registered Users Posts: 130 ✭✭
in Solar Beginners Corner #1
Hi People,

I'm about  to connect just half of my offgrid future 10 panel system.  So I have 5  100 watt 12 volt panels going into a combiner, just using one of my two breakers.  From there onto the Flexmax 80 and then to the 4 Costco 6 volt batteries.

The panels are going to be in series...total voltage of approximately 90 here in the summer.

My questions....

The panels have 12 gauge mulitstrand wiring...no fuses inline....what wiring should I use to the combiner?  (i need an extension) And does wiring for AC differ from DC wiring?  Should i insert one fuse per panel line or?

What gauge wiring from the single breaker to the Flexmax?  And size from Flexmax to the batteries, allowing for the future expansion to 10 panels.  The distance is less than a foot or so from each component.

Thanks so much for your help.

Chris
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #2
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    Chris you won't need a breaker or fuse for 1 or 2 strings of panels. In fact you could/should just use a "Branch connector" unless you intend to add more than 2 strings.

    The panels will have a fuse rating on the back (generally). For strings of 100 watt panels you will usually find it's a 15 amp fuse or breaker for each string.

    Once combined the amperage doubles, but with 2 strings of 100 watt panels putting out about 90 volts (18 volt panels, summer voltage will actually be lower than fall and winter, colder panels =higher voltage) you could use a 25-30 amp fuse or breaker going into the charge controller, this would be handy for shutting down if needed.

    From the Charge controller to the battery bank will depend on system voltage, if it's 12 volts you will have a potential of 1000 watts at 12 volts or @83 amps. For a wire gauge to handle 83 amps (it will rarely if ever be this high) 6 gauge should be fine and likely even 8. For 24 volt battery bank 8 or 10 gauge.

    Outback has a string sizing tool, you can plug in numbers and I think it will give gauges and fuses.

    http://www.outbackpower.com/outback-support/string-sizing-tool

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Chris11
    Chris11 Registered Users Posts: 130 ✭✭
    #3
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    Thanks Photowhit.  I just went and bought some 8 gauge stranded.  Now to install that and the bats.  If you don't hear back from me send flowers to my widow. 

    Chris
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #4
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    I forgot to mention, be sure to get DC rated fuses and breakers! And check that they are designed for enough voltage!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Chris11
    Chris11 Registered Users Posts: 130 ✭✭
    #5
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    Yep, gottem already.  Thanks again.
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