Choosing kAIC on PV inverters (AC Side)

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• mike95490 Solar Expert Posts: 9,270 ✭✭✭✭✭

  December 2016 #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)
  

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• BB. Super Moderators, Administrators Posts: 31,646 admin

  December 2016 #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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