Putting It All Together

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System
System Posts: 2,511 admin
in Off Grid Solar & Battery Systems #1
I have finally acquired all the major components for my off-grid system. I have limited space, so instead of using my needs as the deciding factor, I just bought what would fit. I will just have to live with what I've got. Now, I have to put it all together. Here's what I have:

8 Sharp ND-167U1Y 167 Watt Solar Panels
8 Energizer GC2 6v Golf Cart Batteries (24v bank)
Apollo T80 Charge Controller
Magnum Energy MS4024AE 120/240 Inverter/Charger
Midnite Solar MNE250STM-L-240 E-panel

I have a couple questions.

The E-panel, at one time, came with a kit for use with the T80. Now it doesn't. I think it included 80 amp breakers. Do I need these?

The MS4024AE manual says to use dual 4/0 cable to and from the batteries up to 15 ft. And not recommended for use with batteries further than 15 ft. Mine may be nearly 20 ft. Would the dual 4/0 cable still be alright? Is there a dual lug I can get for the dual cables or do I just use 2 lugs?

Thanks
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  • Robin Gudgel
    Robin Gudgel Registered Users, Solar Expert Posts: 58 ✭✭✭✭
    #2
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    Re: Putting It All Together

    We discontinued the Apollo kit because all E-Panels now have the panel mount knockouts necessary to hold the 80 amp style breakers. You will need to get the MNEDC80 breakers though.
    I wouldn't worry about using dual 4/0 cable. It just isn't necessary. You can measure voltage drop, but in 20 years of building inverters I don't see the need for this. 20 feet is getting a bit long, but unless you have huge surge loads, it will not be an issue.
    Robin
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  • System2
    System2 Posts: 6,290 admin
    #3
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    Re: Putting It All Together

    Wow, straight from the MAN himself! Thanks Robin.

    I think I can get the distance down to 16 or 18 ft.
    I'll order those 80A breakers ASAP.

    I also need to get a combiner box.
    I like the MNPV6 but I'm leaning toward the Baby Box.
    I'll have 4 strings of 2 panels each.

    This the info for my panels.

    Open Circuit Voltage (Voc) 29.04V
    Maximum Power Voltage (Vpm) 22.97V
    Short Circuit Current (Isc) 8.02A
    Maximum Power Current (Ipm) 7.27A
    Rated Power (Pmax)* 167W (+10% / -5%)
    Module Efficiency (hm) 12.7%
    Maximum System Voltage 600VDC
    Series Fuse Rating 15A

    I guess this tells me I need four 15A (MNEPV15) breakers.
    Can I fit those, a ground lug and a couple of short bus bars in the Baby Box?
    Does NAWS carry the Big Baby Box?

    Thanks
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  • Robin Gudgel
    Robin Gudgel Registered Users, Solar Expert Posts: 58 ✭✭✭✭
    #4
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    Re: Putting It All Together

    You don't want to use the Baby box as the PV combiner. The Baby and Big Baby are intended to be used where you just need a few DC breakers. They are not an outdoor box. The Baby has no room for a PV negative or ground bus or plus busbar. You could possibly fit these into the Big Baby, but it is not a combiner either. By the time you added up the Big Baby, a PV minus busbar and a plus busbar, you would be at $73.00. You will notice that the MNPV6 is quite a bit larger than the Big Baby. The MNPV6 is as small as you want for a 4 position combiner. It is also listed to UL1741 and th Big Baby isn't. Naws sells all our stuff, so ask what they will get you an MNPV6 for. There is a reason the MNPV6 is the largest selling PV combiner in North America. Of all the stuff I have designed over the past 20 years, That little combiner is one of the most successful.
    Robin
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