New Growatt 12 Offgrid Solar Install Questions

NewGuyNoob

New Member
Joined
Jul 30, 2021
Messages
9
Hey Guys/Gals,

I have a background in a lot of different things, but not much in electronics :)

I plan to install this system below, I have already purchased these items below, but I go to physically pick these items up tomorrow.

1 x Growatt 12K offgrid Inverter
20 x 72cell 370W Rene Sola Panels
2 x Gill 48v LifePo4 5kw Batteries

Question: If I wire these as 5s2p (each string, total of two strings in my system) my Open Circuit Voltage is approx 240 volts (each MPPT is max 250). Should this be calculated as Open Voltage or Max power Voltage?

Also, I am aware there is a coefficient for cold weather and I could go beyond this threshold, so If Open Circurt Voltage, then I have to reduce this voltage, but if based on max, then it would be approx 219v, which I feel is safe. I plan to use 10AWG PV wire, the run will be approx 130/150ft away. Ground Mount installation, temporary as I am in my homes build site, in a fifth wheel.

Question: The gyll battery uses 6AWG to the battery "rack" busbars, which I do not own. What AWG gauge should I use to parallel these and connect to the Inverter? I have 00 gauge wire which is probably overkill, My use at the moment is not 12KW, about 5/6KW is my planned usage if running my two A/C's (13btu, 1500btu, 120V/15 amp) Generally speaking, I plan to use one only, maybe two for testing the system out. But that is alot of energy usage.

Question: The Growatt 12K inverter, what size are the battery terminals? 6mm? I could not find this in the User Manual or Spec Sheet. Does anyone know? I really need all the sizes actually of the terminals so I can purchase the proper wire sizes and end terminals.

I am new to this entire solar thing, I have completed research for a while now, but I have some many questions and this forum seems to be a wealth of knowledge. So feel free to offer any advice as well!

Thanks!
 

MisterSandals

Participation Medalist
Joined
Nov 5, 2019
Messages
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Location
Silicon Valley
Should this be calculated as Open Voltage or Max power Voltage?
You did not specify the individual panel Voc so have to assume that 5 in series is 240Voc.

This Voc is rated at 25C (77F) and when the temp drops below 25C, the voltage increases by about .3% so it only takes a half dozen degree drop to put your Voc over the 250V limit. And this will probably let out the magic smoke or if you're lucky shut down your SCC.
What AWG gauge should I use to parallel these and connect to the Inverter?
What is the distance, voltage and max amps?
You can determine what wire gauge will keep you below 3% voltage drop here:
 

NewGuyNoob

New Member
Joined
Jul 30, 2021
Messages
9
================== Moved to Off Grid Advice Forum ============================
 
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