DIY Combiner Panel

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
Quick question for a newbie. Is this DIY panel a good idea or should you use DC breakers vice AC?

http://www.solar-power-sales.com/solarpowerdiycombiner.html

Thanks, Sam
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: DIY Combiner Panel

    A couple of comments.

    First, the only breakers that I know of that are DC rated (up to 48vdc) are Square D QO series. Others could cause you trouble with arcing, and potentially welding themselves shut.

    As for the combiner box. How many panels? What kind of inspections are required?

    I don't know why you couldn't use a DC rated breaker box, with a breaker on each panel or several panels, with the breakers sized for the amperage of the panel(s), and then feed the controller from that breaker buss.

    Another option would be to install terminal strips in a weather proof box with lugs big enough to accept the wire size you need, wire the panels to the terminal strip(s) and then home run it.

    A question I once asked, and have never really gotten an answer, is, do you need to fuse (breaker) a PV wire on both ends? In other words, we know there is enough potential energy from the battery to the panels to cause a fire. (Huge capacity of the battery feeding backwards) and so we fuse the battery, but is there enough potential FROM the panels even if the battery fuse would open to cause a fire? I think the smart guys here suggested to me that that couldn't happen, but my memory may be faulty.

    Good luck,

    Icarus

    PS: I'm sure that Bill, Neil, et all will chime in with better info than I can offer.

    PPS: After looking at how they are doing it (following your link) it would work fine if you are wiring your panels in paralell. If you wire your array in series, each string would have to be combined on each breaker, and the every string would have to have similar voltage, which wouldn't allow you to say string 4 panels together in series (48vdc) and then let the mppt controller regulated it back down to say 12vdc. If you are going to buy a good mppt controller, you have to consider the advantage of running the panels at a higher voltage so that you can use smaller wire, and have less line loss.

    T
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: DIY Combiner Panel

    Or possibly another question would be do I need a combiner at this time?
    I have three unisolar-64 panels 12v, Xantrex c40 controller and two lifeline GPL-4DL batteries 210ah each.
    I haven't found an inverter I liked yet, looking for a decently priced true sine one.
    This is just for me to have fun with learning solar and possibly growing it slowly over the years so I would like to have each stop done correctly.
    Thanks, Sam
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: DIY Combiner Panel

    You can plug it all together with Anderson Connectors. Do a search on this forum. We had a long conversation a few days ago on a similar subject. Instead of restating everything, do a quick search,,,

    Tony
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: DIY Combiner Panel

    your first order of business in expanding might be to get another pv because even if those us64s are outputting their rated current of 3.88a that you are on the low side for a charging % being about 2.8%. generally this should be between 5 and 13%, but those batteries can handle an amp for each ah rating or 100% charge rate. i doubt you'll ever need to charge it with that high of current let alone have that much in pv. if the pvs have been allowed to charge without a load or a rare light load then you may be getting away with this being that low. you start utilizing the power (which is a good idea to do or why have it) then you may find your present level of pvs to be insufficient on charge power for your 2 concordes with a ah rating of 420ah totally.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #6
    Re: DIY Combiner Panel

    At this point lets "KISS" ( keep in simple, stupid ) go for these:
    http://store.solar-electric.com/maxfusholinw.html
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  • Redford
    Redford Solar Expert Posts: 38 ✭✭
    #7
    Re: DIY Combiner Panel

    I don't know if I would run 12 guage solid from the modules to the combiner box. Even if it were less than a 10 foot run at 2 amps.

    Other than that it seems like it would work unless it were an older breaker box that used a common ground and neutral buss bar. I don't think those are NEC rated anymore, but I have seen some around.
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #8
    Re: DIY Combiner Panel

    Or you could just get a baby-box + the size and amount of breakers you need and save all the hassle of making your own.

    http://store.solar-electric.com/baby-box.html
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