optimum PV array voltage for 24 volt classic 150 charge controller

Started by TommY, January 31, 2021, 10:10:48 AM

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TommY

I would like some help trying to decide the correct PV voltage for my Midnight 150 classic.  I have 8 Vikram 325 solar panels in 4 strings of 2 panels that I am currently using.  The OCV on each panel is 46.2 volts, and  Short Circuit current  is 9.05 amps.  The classic is putting out max amperage easily in full sun, and very good in the bad days now with over 20 amps in cloudy conditions.  I have over paneled it so we can get more current in low light conditions.  I was wondering if I could put them in parallel and be easier on the midnight charger or would it be better to leave them series parallel like I have them.  I have a 24 volt trace inverter with lead acid batteries ( old and abused) with two other outback MX60 charge controllers on 2 more arrays.  The MIdnight always out performs them, but they all work well together.  I am trying to build another battery bank with 10 Battle Born 24 volt 50 AH lithium batteries, but can't combine them with the lead acid batteries so it will be totally stand alone with another Trace 4024 inverter system.  I have purchased 20 amp breakers for the combiner box if I do parallel the panels so they don't trip the 15 amp breakers I have now.  I have a midnight 12 breaker combiner box on the PV array now that takes the 2 paralleled panels through 1- 15 amp breaker to the buss bar and out on a 4 ga THHN wire to the charge controller. One side to the midnight 150 and other to one of the outback MX 60.  I hope this makes some sense.  Thanks.

Robin

Sounds like you already have the correct combination. 2 in series times 4. Yes, you could put all 8 panels in parallel, but it doesn't sound like you have enough breaker slots left. That would be easier on the Classic, but you will have additional losses in the wiring. I think you should probably stay where you are. When the Trace inverters give out, we should be ready with a few alternatives. All of which will talk to the Classic.
Even though your OutBack and MidNite arrays may not be equal, it always brings a smile to my face when I hear the Classic is outperforming bob's former MX60. The MX60 is also a very good controller.
Thanks,
Robin
Robin Gudgel

Vic

This Post deleted,  for clarity purposes,   we hope ...

Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

TommY

Thanks Robin,  I am in awe of your opinion!  I have owned the original trace 4024 for over 20 years and still no issues... great piece of equipment.  I was thinking I could use the combiner MC-4 plugs  and change the breakers to 20 amp if it would be better, but the line losses and high amperage into the Classic ( have a 60 amp breaker in the panel before the classic) from the combiner might need upgraded too.   I have been trying to read every post in the forum to get educated enough to post and make sense of what I have questions on.  You guys really help everyone a lot.
Thank you very much.

TommY

PS/  I do love the outback chargers too, the cable lugs are larger and the interface is easy to understand.  Don't get me wrong, I love them both but the Midnight has a few more aux capabilities and options that are great.  Thanks again.