How do I size OCPD, Fuse sizing, wire sizing for a 3 phase inverter for a PV install

[wenefredov]

Hi,

I need some help with a project that im working on. Its a 3 phase 480V 4 wire main. I am using 8 qty 20 kW inverters. Output current comes out to 27.3 Amps per phase, per inverter. Can some please let me know if I am doing this correctly??

27.3 A x 1.56 = 42.58 A, so I am using 50A 3 phase PV breaker per inverter in my load center/sub panel.

from my sub panel/load center to the ac disconnect and main service panel I am using:

42.58 A x 8 inverters = 340.7 A, so I am using 350A 3 phase PV breaker and 350A fuses in my AC Disconnect.

my wires calcs from my sub panel to my ac disco and main panel are:

340.7A / .87 / .8 = 489.51A = 700 kcmil where i will use 750 kcmil to accomodate Voltage drop.

Can someone please confirm. I would really appreciate it. Thanks hope to hear back from someone.

 

[Smart $]

Hi,

I need some help with a project that im working on. Its a 3 phase 480V 4 wire main. I am using 8 qty 20 kW inverters. Output current comes out to 27.3 Amps per phase, per inverter. Can some please let me know if I am doing this correctly??

27.3 A x 1.56 = 42.58 A, so I am using 50A 3 phase PV breaker per inverter in my load center/sub panel.

...

How did you determine 27.3A per phase? 20kW is 24A per phase... but if there is an actual maximum output current rating on nameplate or otherwise provided by manufacturer, you have to use that rating.

Also, why are you multiplying by 1.56? The minimum is 125% of output current rating.

 

[ggunn]

What output do your inverters have? 480V 3 phase or 277V single phase?

There is a PV subforum, you know?