12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

GreenerPower
GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
in General Solar Power Topics #1
I wonder where this "12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts / 60 VDC Systems 5000 Watts" STC NEC spec is comming from. This seems to refer only from Outback charge controllers spec and not other CC vendors. I looked though my NEC book and any other references to NEC regarding PV and still couldn't find any. Curious what the basis for these limitations.

GP
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
    Re: 12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

    GP,

    Continuing our earlier discussion from the OutBack forum, I suspect the 125% difference between the FlexMax 80's "maximum solar array" specs and its "NEC recommended solar array specs" is derived from 690.8(A).

    I disagree that these derated specs don't seem to apply to other CC's. The manuals for the Apollo T-80 (page 7), the Blue Sky 6024 (page 13), the Morningstar TriStar (page 1), the OutBack MX60 (page 82), and the Xantrex XW (page 2-2) all include derating discussions.

    Regards,
    Jim / crewzer
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  • GreenerPower
    GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    #3
    Re: 12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

    Jim, I agree with you on the 125% of the Isc STC. I was thinking if I have a 48V system, what limits me from having only 4000W STC worth of PV. Sure I can have 8000W worth of PV if I size the wiring and circuit breakers properly. I think i get it now, I missed the keyword "name-plate". This is for a single FLEXmax80 device. It can handle that much PV wattage. The NEC reference just threw me off to think this is for the whole 12V/24V or 48V system. Thanks,
    GP
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #4
    Re: 12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

    :cool:

    Regards,
    Jim / crewzer
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #5
    Re: 12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

    There may also be UL1741 specific limitations that make this stuff somewhat harder to define.

    boB
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  • GreenerPower
    GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    #6
    Re: 12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

    UL1741 did cross my mind but then I thought this was just the CC and for off-grid system, UL1741 doesn't apply. So my train of thoughts went for more generic case rather than grid-tie.
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #7
    Re: 12 VDC systems 1000 Watts / 24 VDC systems 2000 Watts / 48 VDC systems 4000 Watts

    UL1741 applies to both on grid and off grid, as does NEC. All that fire prevention and shock hazard stuff etc...

    I seem to remember that there used to be a state or two where UL wasn't absolutely required, but I don't know if
    that's still true or not.

    boB :D
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