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diy solar

diy solar

65kw panels+ ~600kwh storage DIY build

empowered

Solar Enthusiast
Joined
Mar 15, 2025
Messages
484
Location
michigan
hey all, newbie here. i'm about in the middle of building my giant solar/battery setup.

its comprised of 2 systems: ~12kw panels+160kwh batteries for the house, and ~53kw panels+~500kwh batteries for my shop/barn.

last fall i got my small system panels installed on the barn, 30 440w sunpal power bifacial panels feeding into SEI 12k UP inverter. as you can see in the pictures, not ideal location, however i did cut down the trees throwing shade on these panels, but they are facing west, and eventually i think i'll relocate them to the big ground array that will be feeding the barn.
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clearing out the area for the big ground array
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as the snow started melting away, i began to install my battery banks.
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temporarily testing battery/inverter comms
1742761831851.png

the battery packs are from work, they were used for development, and cant be sold, so i saved them from getting destroyed. the ones for the house i had to butcher up and rewire to work in 48v config, as the pack is set up for 360v nominal voltage. for the big shop system, i have a 50kw Deye 480v 3 phase inverter that does directly communicate with the pack bms.

so i just finally got some of the battery groups hooked up, still 3 groups to go, and then i'll also have a 2nd pack that will sit in this small shed that i'll need to hook up.

wiring all the 16s groups in parallel to the JK 300 amp bms, finally got it talking to the inverter and working through getting all the settings correct etc.
its been quite the challenge as i'm not very electrically inclined, lol. but the guys from work are helping me out with some pointers etc.

still trying to figure out this SEI inverter settings, seeing some different readings between the inverter and my main house meter, as well as it doesnt want to pull charge out of my battery up to the limit set in the BMS.

anyone out here using SEI/SRNE inverters thats well versed in their settings/config?
 
Welcome to the forum.

Damn that's a massive amount of storage and panels, I'm jealous. I can understand why you would need / want that much.
I considered packs similar to them from Battery Hookup awhile back.

Sorry I can't help with the inverter / BMS comms, if you search for the HESP you might find some more info.
I've been running my ASP's open loop. Can you change your battery type to user / lead acid for a test to see if the AIO or BMS is limiting discharge?
 
only ONE BMS?
the way i understood it, my inverter can only talk to 1 bms, even though i can parallel several of them together, and therefore wont report things like SOC properly.

what are the downsides? as long as i dont draw more current than the BMS is capable of controlling, shouldnt be an issue?
 
Lack of redundancy and heavy loads on a single BMS would be my biggest concerns.

I'm pinging @agtcovert , pretty sure he is successfully using those BMS in parallel with communications.
:waves:

I have 5 in parallel, will be 8 in the next 2-3 months. I don't use closed loop though, I've tried it but didn't like how the battery charged.

If you're doing 48V 16 cell configuration, you definitely want each grouping of 16 cells to have its own BMS. Any standard RJ45 cable run between the two rightmost connectors as you face the IO board will let the master BMS communicate w/ all. First BMS should have the DIP switches all down (id=0).

These 5 are reporting data that's all coming from one BMS connected to Solar Assistant.
1742770784039.png
 
:waves:

I have 5 in parallel, will be 8 in the next 2-3 months. I don't use closed loop though, I've tried it but didn't like how the battery charged.

If you're doing 48V 16 cell configuration, you definitely want each grouping of 16 cells to have its own BMS. Any standard RJ45 cable run between the two rightmost connectors as you face the IO board will let the master BMS communicate w/ all. First BMS should have the DIP switches all down (id=0).

These 5 are reporting data that's all coming from one BMS connected to Solar Assistant.
View attachment 287187
which bms and inverters are you using?
 
the way i understood it, my inverter can only talk to 1 bms, even though i can parallel several of them together, and therefore wont report things like SOC properly.

what are the downsides? as long as i dont draw more current than the BMS is capable of controlling, shouldnt be an issue?
Single point of failure.
 
If your dead set on comms you could leave one bank connected to the SEI with your current BMS then add the original JKs, or other BMS, to the other packs.
Install a shunt on the main negative and call it a day. Oh, I'd also strongly consider quality fusing and/or a high quality breaker.
 
wiring all the 16s groups in parallel to the JK 300 amp bms, finally got it talking to the inverter and working through getting all the settings correct etc.
its been quite the challenge as i'm not very electrically inclined, lol. but the guys from work are helping me out with some pointers etc.
I believe best practice is breaker or fuse per parallel string, along with separate bms. We've seen at least one total loss house fire when a large parallel system had a failure in a megafuse based fusing system where all parallel strings ran through a single fuse.
 
Because they said dip switches and RJ45, it's definitely the inverter BMS.
No need to buy the expensive one, unless you plan on closed loop communication with the inverter.
what do you mean by inverter bms? my inverter does not have a built in bms
 
Check this post out steve knows his shit he’s been working on it

JKBMS Inverter Edition Problems/Issues | No Support / Help to fix major issues. - DO NOT BUY ! Warning (as of Oct.12.2024)​

 
do you know which ones are designated as ones capable of communicating vs not?
For the JK BMS's
If the model number starts with "B" it's the standard (old faithful) version.
If the model number starts with "P" it's the newer inverter BMS.

I use either the B2A20S20P or the B2A24S20P. Whichever is available at the time I'm shopping.
 
For the JK BMS's
If the model number starts with "B" it's the standard (old faithful) version.
If the model number starts with "P" it's the newer inverter BMS.

I use either the B2A20S20P or the B2A24S20P. Whichever is available at the time I'm shopping.
mine is

JK-B2A24S30P-HC and it communicates with my inverter, seems not right?​

 
mine is

JK-B2A24S30P-HC and it communicates with my inverter, seems not right?​

The original versions can communicate with some inverters, with the correct adapter cables.
The newer version was designed as a direct connect closed loop communication model. With all of the standard protocols, ports, and dip switches.
 

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