Wire connection question

bgu1982
bgu1982 Registered Users Posts: 73 ✭✭
in Solar Beginners Corner #1
Hello guys, I have a fairly simple question I'm having some trouble with.

 All I want to do is connect 4 100 watts solar panels running 12 awg wire into a (?) 1 8 awg out that goes to charge controller. I apparently don't know the correct term for what I'm looking for. What I want is a simple screw down type connecter box. Where the 4 sets of 12 awg go into the box( don't know correct term so I'll say box) screw down on the wire for connection and 1 8 awg out with the same type screw down connection. I found car audio things like this but it's in reverse. 1 8 awg in and 4 12 awg out. Would it work in reverse? I don't want any mc4 splitters or anything like that. Just a simple screw down junction type thing.

Thanks for any help
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,102 ✭✭✭✭✭
    #2
    You need a Combiner Box. With 4 (strings of) panels each string needs to be fused. If you have a 100 max Voc MPPT charge controller you could series wire all four panels, creating a single string, eliminating the need for a combiner and 8 awg wire.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • bgu1982
    bgu1982 Registered Users Posts: 73 ✭✭
    #3
    I have a HQST 40 AMP 600 watt mppt controller. 12 awg would suffice for that voltage?
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  • bgu1982
    bgu1982 Registered Users Posts: 73 ✭✭
    #4
    That is what I'll do. I'll wire them in series. Less wire,less work. Thank you. That's why I come to you guys
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #5
    bgu1982 said:
    That is what I'll do. I'll wire them in series. Less wire,less work. Thank you. That's why I come to you guys
    If that controller has a max 100volts input and you live in a climate that get well below freezing, you might want to run 2x2, in series and parallel to keep the VOC below 100 volts (as voltage adds in series and cold weather increases voltage output) Still not a bid issue as you can use 'Y' connectors to combine the strings.

    BougeRV Solar Connectors Y Branch Parallel Adapter Cable Wire Plug Tool Kit for Solar Panel
    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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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,102 ✭✭✭✭✭
    #6
    What is the Voc of these panels?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • bgu1982
    bgu1982 Registered Users Posts: 73 ✭✭
    edited November 2022 #7
    24 volt DC, 6.2 amps max

    So that would would be 96 volts max correct. My charge controller says it's 100 voc input. Is that to close? Can the solar panels make more power than the max rating? In cold weather?
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #8
    bgu1982 said:
    24 volt DC, 6.2 amps max

    So that would would be 96 volts max correct. My charge controller says it's 100 voc input. Is that to close? Can the solar panels make more power than the max rating? In cold weather?
    Yes they can!

    You say 24 volt, Do you mean 24 volt nominal? Which would be to charge a 24 volt battery bank?

    Usually, you can look at the information on the back of the panel and read the VMP and VOC of the panel.

    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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  • bgu1982
    bgu1982 Registered Users Posts: 73 ✭✭
    #9
    No sir, it's for a 12 volt system, usually runs around 19v

    SKU(s)
    57325
    Brand
    THUNDERBOLT SOLAR
    DC Volts
    24
    Accessories Included
    SAE connector
    Amperage (amps)
    6.2 max
    Product Height
    1.4 In.
    Product Length
    36.5 In.
    Product Weight
    15 lb.
    Product Width
    27 In.
    Shipping Weight
    20.90 lb.
    Wattage (watts)
    100
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #10
    Harbor freight stuff, no info available. Really sad.

    In the future, I'd recommend buying from someone who will give you 'real' info about what you are buying.

    Renogy having a Turkey day sale 20% off, 100 watt panels $85 delivered;

    https://www.renogy.com/100-watt-12-volt-monocrystalline-solar-panel-compact-design/

    Specs;

    Maximum Power at STC: 100W

    Cell Efficiency: 22.00%

    Optimum Operating Voltage (Vmp): 20.4V

    Open-Circuit Voltage (Voc): 24.3V

    Optimum Operating Current (Imp): 4.91A

    Short-Circuit Current (Isc): 5.21A

    Operating Temperature: -40°F to 176°F

    Maximum Series Fuse Rating: 15A

    Certifications: CE, ISO

    Maximum System Voltage: 600V DC (UL)

    Weight: 14.1lbs/6.4kg

    Dimensions: 41.8 x 20.9 x1.4 in



    100 watt panels with info and free shipping are available off Amazon for less than $100.

    Here's an example claiming to use high efficency cells, $80 delivered;

    https://www.amazon.com/JJN-Monocrystalline-Efficiency-Battery-Caravan/dp/B09V4ZDJTJ/

    Spec's;

    100w Panel Solar Specifications

    • Module Type: JJN100D-36-M6
    • Maximum Power: 100W
    • Open-Circuit Voltage (Voc): 24.3 V
    • Short-Circuit Current (Isc): 5.21 A
    • Optimum Operating Voltage (Vmp): 20.4 V
    • Optimum Operating Current (Imp): 4.91 A
    • Maximum System Voltage: 600VDC UL
    • Maximum Series Fuse Rating: 15 A

      It will also use connectors designed to be used out side;
      MC4 IP67 connectors for solar panels

      Without Specs, just assume the VOC is too high to do 4 in series, and do 2 in series and 2 in parallel. I think they use auto connectors, you can build your own 'Y' connectors, Do your best to make them water proof and shade/hide them under the panels.


    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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  • bgu1982
    bgu1982 Registered Users Posts: 73 ✭✭
    #11
    Yes, any future solar panel purchase will be of a higher quality brand. But i I have 6 of the harbor freight 100 watt ones that seem to be working fine. I will do as you said and probably do 2 sets of 2 in series the parallel them together. I believe that would be the correct way.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #12
    I usually make this type of post for others who might be following the thread.
    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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