SolarAlternativesDesign
Senior Member
- Location
- Soulsbyville, California, USA
One of the sizing requirements conductors is that the conductor shall be protected by the OCPD, "where required." [2011 NEC 690.8(B)(2)(c)] Our common practice has been to size the inverter - service panel conductor to be protected by the backfed breaker in the panel. The only time the current would be higher than the inverter output is in the case of a fault causing current to flow from the panel to the inverter.
What about the PV output circuit between the combiner box and inverter? Our common practice has been to install fuses only in the combiner, between the combiner output bus and the modules, but not in the inverter.
Similarly, if there are only 2 modules we do not protect the circuit with fuses. We have assumed that current can only flow from modules to inverter and not the other direction.
Is this valid? Could there be some kind of fault current flowing from the inverter to the combiner box?
:?
What about the PV output circuit between the combiner box and inverter? Our common practice has been to install fuses only in the combiner, between the combiner output bus and the modules, but not in the inverter.
Similarly, if there are only 2 modules we do not protect the circuit with fuses. We have assumed that current can only flow from modules to inverter and not the other direction.
Is this valid? Could there be some kind of fault current flowing from the inverter to the combiner box?
:?