MC Cable connections

I'm adding 3 more solar panels to my array. Because of availablility, I'm adding BP Solar panels instead of the original Matrix panels. In my original configuration, I've wired my Matrix in series using 6 gauge copper wire, pig-tailed from the box w/10 guage wire. I'm wondering if I should do the same for the BP panels or if I should use the MC cable connectors that are factory made. Any suggestions? For clarification, I ran the + side of the 6 ga from my pv breaker box to each individual panel (about 40 feet to the furtherest panel) and pigtailed the connection at the junction box. My - side is 6 ga, one wire run with all the panels spliced to it. Seems to me I'm going to have to splice to the mc connector at some point so why not just run the 6 ga all the way to the junction box at the panel? I'm saving 72 bucks on the cost of the cable. I already have the 6 ga wire to do the runs, I think. I may have to buy a little more. Thanks for the help, group.

Dusty

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: MC Cable connections

    if bp solar allows you to bypass the mc connectors without violating any warrantees, then by all means wire it up with the heavier wire into the box. many pv manufacturers don't want you to do that or even to cut off the mc connectors. i don't like that insistance as it limits our connection ability rather than expanding it.
  • dhilldhill Solar Expert Posts: 47
    Re: MC Cable connections

    Thanks, Niel. I'm not sure what I'll have to cut to wire into the box, but for sure, I'm going to have to cut the mc cable somewhere to bring the 6 gauge to it. Seems to me a waste of money to buy a 36 dollar cable just to have a connector on one end. Why not just cut the connector out and hardwire the cable from the box to the 6 gauge?
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: MC Cable connections

    I haven’t looked, but does anyone sell just the connectors you could wire to? If it is a normal junction box it would be easy, but if it just has pig tails to MC I would buy the wire and splice into it.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • dhilldhill Solar Expert Posts: 47
    Re: MC Cable connections

    I haven't seen a good diagram of the junction box so I'm not sure if it's accessible. The box has pre-wired cables and it's suggested to me by the retailer to buy the mc connector to hook into the pre-wired connection. I'm just wondering if I should buy the mc connector cable and splice into it or splice into the pre-wired cable. It seems redundant to buy the mc connector when I'm going to have to splice into the wire somewhere anyway. Thanks for the input, Brock.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: MC Cable connections

    I am so with you on this. I have avoided the MC connectors so far, but I keep wondering about them, it would be easier to connect, but then again if your series and paralleling them you need to get to some other connection anyway.

    Someone must sell just the bare ends?
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: MC Cable connections

    actually to keep the warrantee and have a different gauge wire to it it is best to splice something like this http://store.solar-electric.com/20inmcpisetf.html to the mc connector on the pv or get a length of wire say 3 or 6ft long with mc connectors on both ends and cut it in half allowing for 2 pv connections to be made. these are great for idiots to make connections, but we aren't idiots and need different gauge wires most of the time. the mc wires actually introduce higher v drops for long runs. if you must standardize connections it has to fit the bill for all occasions and these don't because you have little choice in the wire gauge unless you splice to the mc connections like i outlined above. gee we aren't supposed to be smart enough to make connections in a junction box, but we're smart enough to have to splice outside of the jbox with possibly another box or exposed connections using other methods. kind of defeats the purpose and makes matters worse in most cases along with higher unnecessary costs, imo.
  • dhilldhill Solar Expert Posts: 47
    Re: MC Cable connections

    Thanks, niel for showing me those pigtails. I wish I'd seen them when I put together my wire runs for my Matrix. With those panels, I had to go inside the j-box because they allow for establishing 12 volt or 24 volt for each panel. The pigtail would have made it easier for me to run my wiring had I used MC connector cables. Anywho, I made my own pigtails and ran much heavier guage wire in order to control voltage loss. I think I'll do the same thing with the BP panels, only I may be snipping the factory set mc connections and using that as a pigtail. I think it will work just fine, but you are also so right about having the splice exposed to outside elements when it must be done outside the box. Thanks for the help, Brock and niel.
  • System2System2 Posts: 6,290 admin
    Re: MC Cable connections
    Brock wrote:

    Someone must sell just the bare ends?

    for whatever it's worth, i heard the guys at krannich (where i got my suntechs) are now selling the double insulated pv wire that everyone's talking about - with and without the connectors.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: MC Cable connections
    Brock wrote:
    I haven’t looked, but does anyone sell just the connectors you could wire to? If it is a normal junction box it would be easy, but if it just has pig tails to MC I would buy the wire and splice into it.

    http://store.yahoo.com/wind-sun/20inmcpisetf.html
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: MC Cable connections
    joule-r wrote:
    Brock wrote:

    Someone must sell just the bare ends?

    for whatever it's worth, i heard the guys at krannich (where i got my suntechs) are now selling the double insulated pv wire that everyone's talking about - with and without the connectors.

    All MC cable is double insulated, always has been
    62.7417-00122%20FLEX-SOL%204,0%20SN_b.gif
  • System2System2 Posts: 6,290 admin
    Re: MC Cable connections
    wind-s2 wrote:


    All MC cable is double insulated, always has been
    62.7417-00122%20FLEX-SOL%204,0%20SN_b.gif

    cool...i remember their connectors were ul "recognized" but i didn't realize their cable and connectors finally went from recognized to listed. i posted previously about the ny inspector from hell and my buddy's installation...the pv runs were another sore spot...he actually made us pull them and install whatever the other brand is...aarrgghhhhh!!!!
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