Figuring out Breaker Sizes For a 48V Off-Grid System
I am upgrading a 48V off-grid system in Haiti (equipment in my signature); I have posted in a couple other forums and received some good feedback. I also got some great advice from an esteemed "old friend". I will be travelling by the end of he month to do the upgrade, and would definitely appreciate if you could help reviewing and filling the gaps on my configuration.
Array 6 X 315W panels (1890W) in a 3S2P configuration - Array VMP 111 Volts - PV Array Current 17.04 Amps - ISC Array 17.86 Amps - Max Output current based on this configuration 76 Amps
Combiner Breakers: 2 MNPV15 – Breakers may not be necessary for 2 parallel strings, they will be handy for testing and troubleshooting.(Panel fuse is 15 A)
PV Output Disconnect Breaker = 100 Amps (76 Amps CC Max output * 1.25 NEC derating = 95 Amps) Cable 4AWG THHN
PV Input Disconnect Breaker = 50 Amps ?? - This breaker will make it easier to service the controller.
17.86 Isc-array *1.25 NEC derating =22.32 Amps
8 AWG RHW PV cable(33ft) will run in conduit from the combiner to a PV+bus added to the MNDC enclosure - a 4 AWG THHN cable will go from PV+bus to breaker to Classic P+
A 50 Amps breaker was chosen because of the ampacity of the 8 AWG PV cable, and since smaller breaker rating can be used on a heavier wire, the rated ampacity for the # 4 AWG wire was ignored. Thoughts?
I have another question reading inverter breaker, but I am saving it for later.
I appreciate you took the time to read this post.
48V Off-grid System - 1890W panel array (6 x 315) in 3S2P configuration, MNPV3 Combiner, MNDC Enclosure, Whiz Bang JR, Classic 150 CC, 2.5K Inverter Cotek SD-2500-148, 4 x 12v 204 AH FLA Trojan (SPRE 12 225)...