Combining Valence batteries

[Jrv8984]

Just found this forum. I'm in the process of installing my PV system (2) 12k sol-ark inverters, 26kw of panels. I've got (20) U27-12xp batteries and interconnect cables from the smith trucks to make (5) 48v strings. How are you guys combing your strings in parallel? Busbar, midnite solar mnlbc-w250, etc?
Are you using some type of overcurrent protection on each string?
Also what is the amperage of the batteries? The Sol-Arks continuous battery charging output is 185a.
Thanks

 

[svetz]

Not an expert on combiner boxes (I have the Enphase, but they're AC), but have heard good things about Midnight. Not trying to plug them, but everything on the AltE store looks like quality stuff to me. Did Sol-Ark not have a recommendation?

 

[fisherus]

Do you have two Sol-Ark 12k's or thinking about one? The reason I asked is it shows you how to string your panels to run and connect to the Sol-Ark 12k in your installation manual. Shows you options for stringing panels in series and parallel coupling which, when used with the proper Y's can eliminate any combiner boxes. I think that the Sol-Ark 12k EMD hardened is without anything close by comparison and has the best and longest warranty in the business. But, you either need to read the instructions printed in the manual or admit to just looking at possibilites before posting questions that you should already have the answer for.

 

[Jrv8984]

I have 2 sol-arks. But I am asking about connecting the battery bank to the inverters.

 

[fisherus]

How many amps on each string? I'm assuming that you are connecting 12 volt batteries per string. The amperage will dictate what you will need to parallel your strings to the 4-0 cable to your Sol-Ark 12K. I think that you should look at David Poz's YouTube channel and search how he fused and buss barred his "Tower of Power." I backfed my LTO SCiB batteries through a 225amp Square D breaker box using 2-pole 20AMP breakers. I think that your AMP's are too high with your battery mix as each of my batteries are at 60V 45AMPS ea.. I liked the way David Poz did his large 24V batteries he ran 4 strings of 2 paralelled on 2 large buss bars then to fuse and disconnect switches. Disconnect switches are a little overkill with a Sol-Ark 12K but are additional safety. You don't need anything from Midnight Solar to accomplish what you need at a much lower cost.

 

[Samsonite801]

I have 2 sol-arks. But I am asking about connecting the battery bank to the inverters.

Well the good news about Sol-Arks is they have all master breakers built-in inside right on the inputs/outputs, so you only really need combiner function on the DC bank connection... (you do still require a DC breaker disconnect on your PV input near the panels)...



If you have multiple banks going in parallel though, it's good to consider having a breaker on each individual parallel string, so if you need to do maintenance, you can disconnect that one string and not kill the other battery banks' connection to the inverter... Or you could just be really careful not to ground your wrench as you are disconnecting a live string...

 

[Jrv8984]

Recommendations for breakers for the individual strings.