How do you connect 30A MC4 Y connectors to 50A MC4?

hmong2017hmong2017 Registered Users Posts: 39 ✭✭
edited March 2018 in Solar Beginners Corner #1
I am building my own solar system. 
Here is my solar information:
24V, 260 Watt per Panel. I have 6 Panels. Each solar panel rates 8.37AMP. 
I am at 50.22 AMP running down the line to the 80A charge controller if I parallel them. 

The problem I am stuck on was, I can't seem to find any 50A MC4 adapters to attach on my 2 Gauge wire. 
My 2 gauge wire is 50 ft long, from my Charge Controller to my solar panels. 

I plan on using the standard 30A MC4 2 to 1 Y adapter to connect 2 panels,  I then connect all of the 2 to 1 Y adapters ( total of 3 Pos and 3 neg) into the 3 to 1 MC4 Y connector 50A pos and neg.  

Now I am stuck, I don't have &  can't find a 50A adapter to crimp my 2 gauge wire on it to connect to my panels. 
I hope I made sense and that you understand. 
I am starting to assume that I will have to use a 30A to crimp my 2 gauge huge wire and use a 30a mce to connect to a 50a MC4? 

Also, Can standard 30a MC4 clip on with 50a MC4s?  or is the 50a MC4 is a lot bigger? Never seen one before. 
If these two question is solved then I am ready to order my stuff in. 


  • littleharbor2littleharbor2 Solar Expert Posts: 1,862 ✭✭✭✭✭
    You need to terminate your strings in a Fused Combiner box.  Anything more than 2 parallel strings require individual circuit protection.   From there you don't need MC-4 connectors and can run from combiner to controller or breaker box in conduit.

    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.

  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    You'll need something like this to combine the panels, maximum  two panels in parallel, any more than that, there is the possibility of a failed panel being back fed by a potential greater than a single panel. Having a single breaker per panel is useful in trouble shooting, combiner are available with more breakers than the linked example.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • Raj174Raj174 Solar Expert Posts: 795 ✭✭✭✭
    What is the VMP voltage of the 260 watt panels. If it's around 31 volts, it's a 60 cell panel and not a true 24 volt nominal panel. Which means this panel wired in parallel will not have sufficient voltage to charge a 24 volt battery and the panels will need to be wired 2 in series by 3 in parallel. If the VMP voltage is about 36 volts then it should work ok.

    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
  • PhotowhitPhotowhit Solar Expert Posts: 5,991 ✭✭✭✭✭
    To continue with @Raj174 thoughts on the voltage of panels and your overall system. What 80 amp charge controller are you using? Most that handle 80 amps are MPPT type. 

    MPPT type are good for this type of problem because they allow you to connect the panels in series, perhaps 2 strings of 3 panels to avoid needing fusing, as @mcgivor has said. When you add panels in strings, the voltage adds and the amperage stays the same. This is desirable for traveling longer distances with less loss of power(wattage) due to voltage drop in wires.
    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, 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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