How to wire using mc4 style connectors?

nobody928
nobody928 Solar Expert Posts: 62 ✭✭✭✭
in Solar Beginners Corner #1
I am using standard pv wire ( I think 10 gauge if not mistaken). I have a run of about 25 feet from roof to charge controller.

I have four panels and 6 "Y" style connectors. I have the panels run parellel using two Y connector for each set of two panels. I then have an additional two Y connectors to join both sets of panels together along with a 3ft run of additional pv wire to inter connect the second set of panels to the common Y connectore.

Is there too many connections here? Could this be a problem?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: How to wire using mc4 style connectors?

    Yes, there could be a problem here. For one thing you have three parallel connected panels with no circuit protection. Not required to work and probably nothing will ever happen but it is recommended that when you go beyond two parallel connections some form of over-current protection is added to each string just in case one of them goes bad and becomes a shorted conductor.

    Second, how much current are you adding up and putting down that 10 AWG wire to the charge controller over 25 feet away? The factors of wire size, Voltage, and current lead to issues with overloaded wire and too much Voltage drop over the distance.

    The normal course of action would be to join the panels at the array in a weather tight combiner box with circuit protection. Then run wire of appropriate size for the power from there to the controller.

    Those 'Y' connectors are meant for small, two-panel installs on things like RV's and such.
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #3
    Re: How to wire using mc4 style connectors?

    Does anyone make inline MC4 cable fuse/holders?
    That would make life rather easy.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: How to wire using mc4 style connectors?
    jcheil wrote: »
    Does anyone make inline MC4 cable fuse/holders?
    That would make life rather easy.

    I believe so. Think they popped up on the forum before.
    But the problem there is that when you start needing the fuses the current has got to the point where the standard 10 AWG PV wiring is possibly not the right choice for the run to the controller.
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