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Off Grid Installation: Newb need help

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Nov 19, 2022
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Hi Everyone. I am currently in the process of installing my solar system for my Off Grid Cabin, soon to be home.
I will have a lot of questions as I proceed. The hardware I have is for a 48V system. I just set up my ground mount solar panel array, 6- 480Watt Qcells solar panels. Midnight MNPV6-Disco string Combiner Disconnect, Midnight Classic 150 charge controller, Samlex 4248 Split Phase Inverter, Samlex MN175SM-240 E-Panel by Midnite and a Sigineer 10KWH LiFePO4 Battery.
My cabin is a little over 100 feet away from my panels and I plan on using #4 stranded wire from my disconnect to the charge controller.
First question I have is hooking up the panels to my combiner box..I was going to run 3 strings of two panels? Also would like to know how I should ground this part properly?
tempImageDRKC5L.png
 
First question I have is hooking up the panels to my combiner box..I was going to run 3 strings of two panels?
What are the specs on the panels? Also, the record cold day of the year?

My guess without knowing the specs is that 3s is all that a 150 volt SCC can handle. There’s a temperature coefficient that pushes pushes voltage higher as temps drop. I’m guessing from the pine trees the winters are a bit chilly.

Your Midnite Solar 6 string combiner will leave you a bit of room for expansion. I assume you’re combining at the panels. Will you install wire that will handle the additional amperage?
 
Specs of my panels is attached.
Cold temperatures run about -15 degrees Celsius. Average cold temps are around -5 degrees Celsius.Solar Panel specs.jpg
 
Just measured voltage from one panel at 52.24 volts, at 6 degrees celcius
 
Just measured voltage from one panel at 52.24 volts, at 6 degrees celcius
If that's the case, you need to check the specs of the SCC prior to hooking 3S up. Normally, exceeding the 150 volts of the controller is bad, as in controller going up in smoke bad. Perhaps the Mindnite SCC has a Hyper-VOC mode where it can exceed that.

I'd run the panels at 2S. That's a shame because that could mean about 1/3rd the potential power won't happen. Matching the big panels to a charge controller is a bit hard.

2S does have a reasonable amount of loss for a 100' one way run of 4 AWG:
1669582255811.png
The numbers in you put in the calculator will change the loss a little, mine are a worst case loss scenario.
 
I'm adding a similar setup with 6 panels Q-395's & a Classic-150 to my existing Classic-200 with 2kw of solar. It got a tad bit trickier because I have an MNDC-250 E-panel which now has to accommodate 2 Classics and their output breakers (2x100A). I'm moving the PV Input breakers for both solar racks to my Midnite Big BabyBox to accommodate it all. At least now I'll be able to push 170A at my 1293AH/33.1kWh battery bank.
 
What abound grounding the system? Do I ground all the panels together to a grounding rod in the ground, or can I just run a ground wire from the combiner box to the grounding rod?
 
My solar racks are Wood with Kinetic Solar Rails with the panels mounted to them. Rails & Panels are bonded together and grounded to a Ground Plate 30" deep in the soil. They are NOT connected to my AC Common Ground as the DC at that point is independent. My Classics are attached to the E-Panel which is attached to the Common Ground, as is my inverter system. My Common Ground is actually my 6" Well Casing that goes 24' down and is sealed into the granite bedrock. I have Midnite DC SPD's in use on the E-Panel.
 
So I don't have to run a ground wire from my disconnect/combiner box to my e panel?
Essentially having two ground systems, one for the DC portion and one for the AC component? Is that correct?
 
Correct, the Panels, Rails and mounting hardware is not "electrical" as such but it can be a lightning rod. DC only has (+) & (-) so...

My Inverter, E-Panel etc are grounded to the Common Ground my AC uses which is the Well Casing.
 
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