Requirement of Overcurrent Protection
As per IS/IEC 62548, an overcurrent protection device (or a DC Fuse) is required in a system, if the below mentioned condition is true:
[(Ns – 1) x Isc_mod] > [Imod_max_ocpr]
Where,
Ns = Number of strings connected in parallel (To be determined from design considerations)
Isc = Short Circuit Current of Solar PV Modules at STC (To be determined from Datasheet)
Imod_max_ocpr = Max Series Fuse Rating (To be determined from Datasheet)
Sizing of solar DC fuse
As per IS/IEC 62548, current rating of an overcurrent protection device (or a DC Fuse) should be calculated as:
In > 1.5 x Isc_mod
In < 2.4 x Isc_mod
In <= Imod_max_ocpr
Where,
In = Current rating of DC Fuse
Isc = Short Circuit Current of Solar PV Modules at STC (To be determined from Datasheet)
Imod_max_ocpr = Max Series Fuse Rating (To be determined from Datasheet)
Voltage rating of a DC Fuse should be equal to or more than the string maximum voltage