Off Grid Cabin Wiring with my Xantrex TR2412

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #32
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    Re: Off Grid Cabin Wiring with my Xantrex TR2412

    Yes, flooded cell batteries should be vented to the outside--The mist from charging can be a pain. Water Miser caps can help, but not eliminate. Also, from a safety point of view, AGM/Sealed/GEL batteries can vent too (over charging, near end of life, etc.).

    If you use sealed batteries, I would high suggest a Battery Monitor (Victron is another good brand). You cannot measure specific gravity with sealed cells, so a battery monitor (correctly setup) is almost a requirement. If you are the only one running the system, you can possibly get away with using a volt meter to monitor the system--But is it not as easy (or as fun:roll:) as a battery monitor.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Timinator
    Timinator Solar Expert Posts: 32 ✭
    #33
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    Re: Off Grid Cabin Wiring with my Xantrex TR2412
    Cariboocoot wrote: »
    If you've never had a system before, don't buy any type of sealed battery to start with unless it is absolutely necessary. It's much easier to keep an eye on flooded cells and they are more forgiving of mistakes.

    Something that needs to be clarified about the N-G bond:
    Blackcherry04 speak of 'lifting' it when shore power is supplied. This applies where the external AC power is from 'shore', as in a marine or RV dock hook-up which will already have an N-G bond at the supply. In that instance you do not want a redundant bond within your system.

    For a stand-alone application such as a cabin there would be only one N-G bond, usually in the AC distribution box, and it does not need to be 'lifted' ever as the generator would not have one.

    Thanks for the clarification about the N-G bond. With everybody's help, I think I got that right now.

    I've never had an off grid house system before, but I've used Trojan T-105's for probably 20 years now in several motorhomes and two golf carts. Same with inverters. I've got a little PWM controller for the one big solar panel and I've been very happy with the performance and longevity I've been able to get with T-105's. The AGM's just seemed to be "newer" technology and I thought it would be nice to be able to keep them inside the cabin instead of boxed outside. But I'm fine with the 105's and know how to keep them happy.
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  • Timinator
    Timinator Solar Expert Posts: 32 ✭
    #34
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    Re: Off Grid Cabin Wiring with my Xantrex TR2412

    I wanted to update my progress on the cabin. A few things have changed and I wanted to make sure I have my ducks in a row. I have two Power Sonic AGM PG-6V210-FR batteries and a new Outback FM60 Controller. I'll be using two DMSolar DM145 12v panels (specs below). I also have another 12v panel, maybe 120 watts or so, no other info known. So, now that I have a MPPT controller, how should I run the panels to the controller; series or parallel? I don't need to run that third panel if that's a problem. I only stay at the hunting cabin a few days at a time and will be coming with fully charged batteries. The panels will be removed when I leave. I do have a backup inverter generator and well as an inverter/charger if the batteries drop below 50% or so.

    DM145 Panels x2

    * Pmax: 145W
    * Vmp: 18.7V
    * Imp: 7.75A
    * Voc: 22.3V
    * Isc: 8.37A
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #35
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    Re: Off Grid Cabin Wiring with my Xantrex TR2412

    If the panels are "near" the controller/battery bank, you don't need to run a higher Vmp-array voltage (may require heavier gauge wire).

    Series would be nice--But if you want to use the "free" solar panel, putting all three in parallel would be "safe". You can only put the 3rd panel in series if its Imp is within ~10% or better of the Imp for your other panels.

    If you put three or more panels (or panel strings) in parallel, you should have a combiner box with a series protection fuse per string (three strings, three fuses/breakers) that matches the panel's requirements (usually around 10-15 amps for your panels listed). The "unknown" panel--You may just need to take a SWAG--Measure its output shorted current and pick a fuse/breaker that is ~1.5x measured Isc (round up to next standard size).

    -Bill

    Hopefully, the unknown panel is Vmp~17.5 to 18.6 volts or so... If it is >>17-18 volts, it may confuse the MPPT charge controller and actually cut your array's performance rather than add to it.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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