PV DC Breaker Sizing for 6500ex MPPT

[jfharper]

We size the PV DC breakers for the Max input amperage rating of the MPPT, not the wire size, correct?

With a Max Input Current Draw = 18A per MPPT, would it be better to go 16amp DC breaker or 20amp? Someone posted go close and a bit over, but I just didn't want to risk damaging the AIO. I know you stay under for the volts calculated for temp, but wasn't sure about the current. The panels will be single series wired and rated at no more than Isc = 13.70 A at STC, I couldn't find the Imp for the highest rated panel, but the ELECTRICAL DATA at Nominal Module Operating Temperature (NMOT) was less then the stated 13.70A.

Similarly, how would I size the SPD? 20KA, 40KA?

 

[pvgirl]

Manual recommends a 30 amp breaker, NEC calculations for an 13.7 amp Isc result in needing a 25 amp breaker. Per NEC breaker size must be greater then the Isc @ STC multiplied by 1.56

 

[pvgirl]

there is no requirement to have over current protection on a single string of panels, so all you really need is a disconnect switch, such a the IMO pv disconnects, but could be a breaker as well.