detached garage

dubdeere
dubdeere Registered Users Posts: 2 ✭
in PV Installers Forum - NEC, Wiring, Installation #1
When adding a pv system to a detached garage that has a subpanel from the house can you use the same feeders to backfeed the ac if the inverter is installed in the garage?
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    Backfeeding is something that can potentially create hazardous conditions to workers repairing line faults in the case of an outage, it is something I would highly discourage, especially from a liability point of view. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,894 ✭✭✭✭✭✭
    #3
    If it is done correctly this is an option. If the PV system is grid-tied the distance, wire size, and panel sizes need to be be checked for correct sizing against the PV sizing.
    "we go where power lines don't" Sierra Nevada mountain area
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #4
    I would certainly run this past the local code department.  Mine wanted it attached to the main panel and the disconnect had to be fully accessible by the fire department and the meter available to the power company.
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited May 2019 #5
    Dubdeere,

    This can be done but to pass the inspector and Fire Marshall the breaker at the main panel feeding the garage must be labeled as the solar feed breaker,  the red alternate power source warning placard must be located there (at the main panel) as well as a pointer to the sub panel where the solar is located, with possibly another red placard at the garage sub panel. This is for firefighter safety.  Wiring must be of ample ampacity to serve this load........This might not be true if your utility uses the two meter type of solar installation. PG&E does not require two meters AFAIK the "smart mater" does this for PG&E. 

    david
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • dubdeere
    dubdeere Registered Users Posts: 2 ✭
    #6
    Just for clarification, this is a grid tied system.   Thanks for your responses.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #7
    Without the inclusion of grid tied in the original text, I had assumed a battery system backfeeding the house, my mistake.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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