How to fish MC4 through a RV gelcoat roof?

Dumbdumbhead
Dumbdumbhead Solar Expert Posts: 28 ✭
in Solar Beginners Corner #1
Hello, I would like to snake some MC4 cable ends through the roof of my rv, however, I believe the solar panel I plan on getting has factory installed MC4 cables on it, 3 ft. to be exact. I was wondering how to minimize the size of the hole I have to drill in order to fish the cable through the roof. The MC4 cables have big connecters on the ends so what's the best method to accomplish this?

I have no experience in cutting or crimping MC4 cable and I really don't want to have to invest in an expensive MC4 crimper just so I can fish the cable through the roof once.

Thanks
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #2
    Re: How to fish MC4 through a RV gelcoat roof?

    The MC connectors aren't good for anything other than connecting the solar panels to each other. To connect the solar panels to something else - such as a charge controller or combiner box - you have to have a normal wire end.

    But you can't cut the MC off or you void the warranty. So you need a way to convert from MC to normal wire end.

    The trick to accomplish that, is to buy an MC extension cable which has one male and one female end, and then cut it in half. Then you have a converter from MC to regular wire for both the positive and negative leads off the solar panel.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,622 admin
    #3
    Re: How to fish MC4 through a RV gelcoat roof?

    Our host Northern Arizona Wind & Sun has pre-made MC4 cables in various lengths.

    As DWH says, just cut them in 1/2 and thread the cut ends into your RV.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dumbdumbhead
    Dumbdumbhead Solar Expert Posts: 28 ✭
    #4
    Re: How to fish MC4 through a RV gelcoat roof?
    dwh wrote: »
    The trick to accomplish that, is to buy an MC extension cable which has one male and one female end, and then cut it in half. Then you have a converter from MC to regular wire for both the positive and negative leads off the solar panel.

    Oh, I get it, I think. But I have another question. What does the inside of an MC extension look like? Are there 2 separate conductors inside? A Neg and Pos lead? Or is it one conductor? I'm guessing there are two conductors by the way you describe it.
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  • Dumbdumbhead
    Dumbdumbhead Solar Expert Posts: 28 ✭
    #5
    Re: How to fish MC4 through a RV gelcoat roof?
    BB. wrote: »
    Our host Northern Arizona Wind & Sun has pre-made MC4 cables in various lengths.

    As DWH says, just cut them in 1/2 and thread the cut ends into your RV.

    -Bill

    Thanks for the link BB, The picture of the MC extension appears to show a single multi fine strand conductor. How do I convert that into a Pos and Neg lead? Sorry, I am totally new to this and trying to piece together the minutia.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,622 admin
    #6
    Re: How to fish MC4 through a RV gelcoat roof?

    No, they are two separate connectors. One Male and one Female with one pin inside.

    wind-sun_2155_48910141
    Also, there are pair of tools to unlatch the connectors for servicing (another NRTL/NEC requirement).

    wind-sun_2155_1558959Disconnect Tool for MC4 Connectors (set of 2)
    Price: $9.00

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dumbdumbhead
    Dumbdumbhead Solar Expert Posts: 28 ✭
    #7
    Re: How to fish MC4 through a RV gelcoat roof?

    Ok, one more question. Can the female end of the MC4 extension be opened so that I can release the cable/conductor it is holding on to or are they permanently married? It would make more sense if this were possible, that way I could release the cable, fish the cable through the roof and then re-marry the female MC4 adapter to the cable/conductor on the inside of the trailer.

    :-)
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  • Dumbdumbhead
    Dumbdumbhead Solar Expert Posts: 28 ✭
    #8
    Re: How to fish MC4 through a RV gelcoat roof?

    Nevermind, I get it. I just watched a video on YouTube about MC4 connectors, makes sense now. Thank you for the help.
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