Breakers and Voc

Volvo Farmer
Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
Having just wired my 24V panels four-in-series, I now have a rated Voc around 176V. However my Vmp is only about 141V.

So these Midnite 150V Din breakers that I need at the panels, are they OK to use with these voltages? I would imagine that the V in might exceed 150V on a cold day or on a sweep. What's the proper way to disconnect an array like this?

Also, I need to upgrade my panel mount breakers on the charge controller from 60 to 80 amps, The only 80a small panel mount breakers I can find are rated to 125V. This will be fine on the output side, but it would seem my working voltage exceeds the rating of these breakers on the input side. Is there a product that would suit my needs?

Maybe I'll just call NAWS this morning. Seems like they have the Midnite Din rail breakers on sale right now anyway.
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Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Breakers and Voc

    Hi you might ask if they have Midnite solar's 80 and 100 amp Din rail beakers in stock! The discription states 150 VDC but you can read 125 VDC on the breaker.

    They do make panel mount breakers up to 100 amps and I think they are 150 VDC.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #3
    Re: Breakers and Voc

    That is a bit high for a standard 150 VDC maximum input charge controller.

    I believe that Midnite supports 150 VDC + Battery voltage--So if you have a 48 volt battery bank connected (and working), it would support 198 volt input array voltage.

    Midnite also has some higher input voltage controller models (with slightly reduced current capacity) too.

    As always, read the manual.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #4
    Re: Breakers and Voc

    Midnite makes 300 volt breakers:
    http://forum.solar-electric.com/showthread.php?p=126607#post126607

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    #5
    Re: Breakers and Voc

    Thanks folks.

    I have a Classic 200 so should be OK on not exceeding the voltage limit on the charge controller, though I am right at the bleeding edge of what this thing is rated for in cold temps. I called NAWS today and found the 300A panel mount breakers. Also the helpful fellow on the phone told me 171V was too high of a rating for these breakers, but Midnite makes a quick disconnect din rail fuse holder. So I bought some of those as well.

    Hehe, I think these Gudgel boys have something going on here, encourage everyone to go high voltage DC, because of nifty charge controllers, then sell all the nifty high voltage stuff you need to hook it up. Seriously though, the prices on the fuses and holders is pretty reasonable, and even the 300V breaker wasn't that bad.
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