Getting ready to setup 48V setup to solark 12k just need some input

myles

Autonomy Expert
Joined
Jan 24, 2021
Messages
84
Hey guys

getting ready to hook up my 48v batteries and get wiring setup for use this summer. My entire house will be off grid, all the heating loads, cooking loads, drying loads will be from the propane or wood heat sources. so the loads are not too high, the biggest load will be a senville 48,000 BTU 4 head mini split AC for summertime, and the dishwasher when it runs during the daytime, it runs everyday as we have 3 young kids. the solark will be tied to the main house panel as this is off grid.

My current hardware:
solark 12k off grid setup
12.5 kw standby propane generator with auto start
12kw of solar input
i have a total of 68 matched cell batteries @ 280ah each. I want to build two seperate banks in a 16s2p config
i have a total of 4 16s 100A chargery BMS, they came with a standard 100A shunt

I need help with the following:
1. what size of battery wiring should i be using, my reading tells me 2/0 battery cabling. The batteries will be within 10' of the elec panel and the solark inverter
2. Do i need a fuse or a breaker after the battery pack? If so what are people using? is this placed after the shunt if the battery is the first thing in the line, or is it between the shunt and the battery pack?
3. i don't think the shunts that came with the BMS are good enough in hind sight. What shunt should i be using? or should i be using jason's 300A DCC instead? Logic also tells me that hoooking up each bank to a bus bar, will yield me a 200A service like this: https://www.mobile-solarpower.com/uploads/1/2/9/6/12964626/cescdsdcd_1_orig.jpg

4. I bought double bus bars and plan to double up the bus bars on the terminals of the batteries. is this a good idea?
5. Why the two battery packs you ask? One complete for backup, and i plan to put a switch on each bank so that i can excercise the backup pack once a month for a few days to keep it in "action" and charged, since it takes months to get these cells from china, i want the redudency.
6. Each battery bank will be on a different shelf in the cabinet, once hooked up in a 16s configuration, can i think put the larger battery leads to an external large bus bar to join the two packs, then output to the shunt/dcc and inverter? see attached diagram. If so, how do we size that bus bar?
6. I have researched ALOT, and i think i have the optimal sizing for our needs, including filling out endless spreadsheets of energy modeling. Am i missing something?

any other input is greatly appreciated!! Very hack wiring diagram attached. The solar part is going to all be hooked up by a profressional solar company that is local, the part i need to take care of on my own is the connection from the battery, to the solark, that is why i am asking here for input.

thanks so much!

my battery post here:
 

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myles

Autonomy Expert
Joined
Jan 24, 2021
Messages
84
battery pack very rough wiring diagram, revised as i realize i need to use each 100a seperate for each back, then a shunt or DCC after the bus bar making the two packs paralell.

again, looking for guidance, correct is much appreciated
 

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