PV inverter sharing circuit breaker

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cris-nov-eng

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Electromechanical Engineer - Electrical an HVAC drawings reviewer
Hello
I was wondering what is the rule that allows to an PV inverter output share circuit breaker already used to protect a LOAD already running?
 
PV inverter output circuits require dedicated circuits. That means there can be no other source or sink of power, between the inverter and the first OCPD protecting its dedicated circuit. One inverter, one breaker. Loads go on a separate breaker, other inverters go on a separate breaker.

The exception is microinverters that are allowed to be paralleled in advance of the branch circuit OCPD, provided that they are paralleled with a method listed specifically for the application. Such as the brand-specific trunk cable that connects a group of microinverters in parallel, to connect that group to the branch circuit breaker. Or the brand-specific aggregator that allows for paralleling multiple trunk cables, to fit it on a larger branch circuit.
 
Carultch said:
PV inverter output circuits require dedicated circuits. That means there can be no other source or sink of power, between the inverter and the first OCPD protecting its dedicated circuit. One inverter, one breaker. Loads go on a separate breaker, other inverters go on a separate breaker.

The exception is microinverters that are allowed to be paralleled in advance of the branch circuit OCPD, provided that they are paralleled with a method listed specifically for the application. Such as the brand-specific trunk cable that connects a group of microinverters in parallel, to connect that group to the branch circuit breaker. Or the brand-specific aggregator that allows for paralleling multiple trunk cables, to fit it on a larger branch circuit.
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Thank you Mr Carultch for the explanation. It will be plenty useful. ¿Do you know in what part of the NEC or IEEE can i find this subject?
 
690 is the article that is specific to PV in the NEC. 705 is another common article that applies, which provides the rules that apply for combining power sources.

The first four chapters also apply, as they contain general electrical construction standards that apply to all installations.
 
The NEC section is in 705.12 and is titled 'Dedicated Overcurrent and Disconnect.' (It's section number has changed repeatedly. )

I really don't think there's a prohibition on having multiple string inverters on one breaker, provided all field wiring is sized for the breaker. However it will usually be limited by manufacturer instructions or practical considerations such as terminal sizes. If the manufacturer specifies a max overcurrent device that only handles one inverter then that will be it.
 
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