Choosing kAIC on PV inverters (AC Side)

squelchea
squelchea Registered Users Posts: 6 ✭✭
in Grid Tie and Grid Interactive Systems #1
Hi Guyz,

on selecting PV inverter breaker, what will be my baseline on choosing its kAIC rating ? this refers to AC side breaker.

any formulas ?

thanks
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    It almost doesn't matter.  Breakers are designed to easily trip on overloads when Hover Dam is powering the circuit,  An inverter is a "soft source" and may not always be able to trip a properly sized breaker,   So you install breakers anyway, properly, but I don't know about a main output breaker.   My inverter has a pretty beefy surge rating for motor starting, and may never be able to trip a breaker sized to pass the starting surge,  Say it's a 10 amp rated, with 20A surge for 30 sec.   How to size a breaker for that ??? (this is an example, not my actual spec)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #3
    Standard US AC breakers are 10,000 AIC rated. This is the designed Pole top transformer and AC drop to home's maximum current.

    No home sized inverter or genset is going to come close to this amount of current...

    10,000 Amps * 240 VAC = 2,400,000 Watts  (VA) = 2.4 MWatts surge current

    That is about 500 to 1,000x larger than the average off grid system's power capability.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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