circuit breaker rating

[Vishnu]

Hallo PVSol Team,

I was wondering how PVSol calculates the rating of circuit breakers needed after the inverter and after the bidirectional meter for a system. z.B. the following system uses Solaredge SE7K 3 phase inverter with max output current per phase of 11,5 Amp. PVSol suggested a 16A breaker. Could you please explain how this suggestion was made?

Thanks.

[developer_mh]

Dear Vishnu,

the current rating for the circuit breakers is determined as follows:

• Determine the maximum AC current of the connected inverters (taking into account the maximum AC output power, the grid voltage and the number of phases)
• Apply safety factor of 1.1
• Choose the smallest current rating that is bigger than this current from the list:
  • 6, 10, 13, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125 A
• The characteristic is always B, except for inverters with transformator (K) oder with ENS (C)

Hope that helps, kind regards,

Martin

[Vishnu]

Hey Martin,

I remember that NEC requries rating the breakers at 125% the full load current. Please correct me if I am wrong. 

Is it different in case of PV systems when it comes to breakers for inverters?

Danke!!!

-Vishnu