Help with Growatt SC 48120 installation

[jkb458]

If anyone could help me with wire, breaker, fuse details, I would like to order my missing parts soon. The panels will be on an attached garage, Growatt and batteries in the garage.
This system will independent of the grid.
Parts I have:
*(12) Santan 250W (used)
VOC 37.6V
VMP 30.3V
ISC 8.85A
Max pwr curr 8.27A
Max system voltage 600
Fuse Rating 15A


*Growatt SC48120 (Purchased directly from Watts247)
https://watts247.com/manuals/gw/Growatt SC48120 SC48100 Charge Controller Manual.pdf

I think I can wire the panels in 3S4P. This Growatt has 2 PV inputs. The longest run from the panels to the controller will be less than 60 feet.

Question: Should I be running wires from each group into a breaker box, or combining on the roof, then through a breaker and into the MPPT? I am unclear on the exact way I need to connect the 4 sets of panels down to the 2 inputs. I would like to have a way to isolate for troubleshooting.

Question: 8 gauge wire from panels to breakers?

Question: Batteries: I have not purchased batteries yet. I am considering two of the Ampere Time 24V 100 Ah. The Growatt manual shows a chart with minimum battery capacity, but I think this is only referring to lead acid. Will two of the the 24V 100Ah, wired in series be compatible with this system?

Question: Breakers or fuses between Growatt and batteries? Size, type?

 

[jkb458]

Correction: I just received the Growatt and unboxed it. It only has 1 PV input. The diagram in the online manual showed two inputs.

 

[timber1111]

check out this handy pv panel calculator for for calculating series/parallel connections:

MidNite Solar - Classic Sizing Tool.

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

Then, my thoughts

4s3p (this will bring your voltage up to what i consider a better voltage for the inverter),
then bring parallel strings to a combiner box that has (3) 15A DC breakers (this provides safety isolation cutoff prior to the charge controller,
from the combiner box go to the charge controller using 6 gauge stranded (due to your 60 foot run and to allow for additional panels later if needed)

You mentioned batteries, 2-24v batteries in series, which sounds fine.......but what about your inverter?

 

[timber1111]

Correction: I just received the Growatt and unboxed it. It only has 1 PV input. The diagram in the online manual showed two inputs.

with your planned configuration and the setup i mentioned, you only need 1 pv input

 

[jkb458]

The Growatt is an all-in-one.

 

[timber1111]

The Growatt is an all-in-one.

Not the one you mentioned....

SC48120 MPV- 120A 48V, 24V and 12V battery MPPT 250V PV 120A Charge Controller only​

 

[jkb458]

with your planned configuration and the setup i mentioned, you only need 1 pv input

The Growatt is an all-in-one unit. My 60' run would be coming from the farthest panel, along the roof, then down into the combiner box. What would be the proper gauge wire for connecting the panels to the combiner box?

 

[jkb458]

The Growatt is an all-in-one unit. My 60' run would be coming from the farthest panel, along the roof, then down into the combiner box. What would be the proper gauge wire for connecting the panels to the combiner box?

Oh...maybe it's linking to the wrong manual...I'll check.

 

[timber1111]

Your post is "

Help with Growatt SC 48120 installation"​

This model is only a charge controller.

As far as your series strings going to the combiner box (which should be located near the panels), 8 or 10 gauge would be fine. But once you combine those strings in the combiner box, you need to go to 6 gauge (some will say 8 awg but I thing 6 awg is safer)

 

[jkb458]

You are correct, my friend. I linked to the wrong manual...hence the mismatched number of pv inputs. Here is the spec sheet for my unit.

 

[timber1111]

Don't mean to beat a dead horse, but can you look on the actual equipment and verify the model number?

 

[jkb458]

SPF 3000TL LVM-48P

 

[timber1111]

ok, then the above config already mentioned will work fine EXCEPT....
use 3S4P as you originally intended, my input into the calculator was wrong when i told you 4S3P

 

[jkb458]

Thank you. I appreciate the advice.