System wiring/sizing help

SystemSystem Posts: 2,511 admin
I am looking for suggestions on the best way to wire 4 panels in parallel to the charge controller and then to the battery bank on a houseboat. I have been reading posts here and understand the importance of having an opcd on the positive leg of each panel. Where is the best place to locate a combiner box/breakers for this type installation: near the panels on the roof or inside the cabin approx. 25 feet from the panels? Can the negative wire be daisy chained from panel to panel and then run to the combiner box if sized correctly?

I am using 4 Solarex VLX53 panels

Morningstar Sunsaver Duo charge controller

3 flodded 110Ah batteries

I appreciate any suggestions.

Comments

  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: System wiring/sizing help

    Best place to put the combiner box would be at the panels. Best to run separate negatives to the combiner. Blue Sea calculator suggests #4 wire from combiner to charge controller (25' 1% voltage drop). That Help?
  • System2System2 Posts: 6,290 admin
    Re: System wiring/sizing help

    Thanks audredger, that is helpfull.

    What would you suggest as the best weather proof combiner box?
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: System wiring/sizing help

    My preference is; http://store.solar-electric.com/pspv.html or http://store.solar-electric.com/mnpv6.html both very good!
  • BilljustBillBilljustBill Solar Expert Posts: 212 ✭✭✭
    Re: System wiring/sizing help

    In reading the wire size recommendations, I'm a bit fuzzy about the number size #6 listed. What I found when I bought 5 Seimens 75 watt panels and their wiring harness that had a volt meter, amp meter, master switch, and solar controller that had a #6 stamped on wiring running between the panels and the controller.

    I took apart an old/outdated Highway Department solar powered sign. It has a 12v system once powered by 6 panels. The cables running from the panel rack that held the panels is stamped a "#6 Essex Excelene....Welding Cable", but it appears the fine wires making up this cable make a much thicker wire than what a #6 is that is for home/commerical use.

    Is there a difference in copper size because one is for a high amp welding/battery cable rating system?

    Bill
    Bill
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: System wiring/sizing help

    Stranded wire does tend to be larger than single wire. Stranded wire should be used anywhere the wire will move. Welding cable has fine wires so it is flexible.

    #6 solid, #6 stranded & #6 welding all have the same amperage rating.

    I have seen cheap extension cords where the #12 gage looked like #14 and #14 that looked like #16!

    If you are going to crimp lugs on wire.... make the lugs are for the correct type of wire.. solid vs stranded vs welding.. they are different.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: System wiring/sizing help

    as to this "Where is the best place to locate a combiner box/breakers for this type installation: near the panels on the roof or inside the cabin approx. 25 feet from the panels?"
    if there is easy access during any time of the year to replace the fuse(s) that may pop or go bad then i'll agree to do this all on the roof. most roof installations are not accommodating so it should be at the first accessible place after the roof and all paralleled wires must run to the combiner box separately and fused in the accessible area usually in the same area as the combiner and is often in the same box.
  • BajaGringoBajaGringo Solar Expert Posts: 40 ✭✭
    Re: System wiring/sizing help
    pwabbott wrote: »
    I have been reading posts here and understand the importance of having an opcd on the positive leg of each panel.

    I did a search here on the forum and the only reference found to opcd was this post. So what is "opcd"??? Sorry for the hijack...
  • BB.BB. Super Moderators, Administrators Posts: 29,724 admin
    Re: System wiring/sizing help

    I think it should be OCPD--Over Current Protection Device (fuse/breaker/etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BajaGringoBajaGringo Solar Expert Posts: 40 ✭✭
    Re: System wiring/sizing help

    Yikes - I should have caught that. I was trying to put something together that made sense for opcd and came up blank. Thanks!

    We now return you to your regularly scheduled programming...

    :roll:
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