Sizing Solar Panel String to CL150

[NevMog]

I have (12) QCell 390 watt panels that I need to run into a combiner box before the CL150 Charge Controller. I am unsure how to series/parallel the strings. ISC 10.14, VOC 48.48, IMP 9.66, VMP 40.38/PMPP+/-3%, VOC+/-5% at STC.
We will operate our system on a Conext SW4048 w/CL150 and an Absolyte GX (AGM) 48 volt battery bank. The goal is to install more solar panel and charge controllers to the system after we are up and operating. Thank you for assistance. I am just getting back to good health after a heart attack and still moving a little slower than I like but I need to get this system up and operating as soon as I am able.

[boB]

I hope you feel better soon !

Since each of the 12 panels have a Voc of 48.5 volts, four strings of 3 in series would just barely   make it under 150 volts.  But, as soon as the weather gets colder than about 20 degrees C, or 68 degrees F, the Classic could go over-voltage.   But you are using a 48V battery so six strings of 2 in series should work great with plenty of headroom for the cold days.

I recommend wiring 6 strings  of  2 panels in series.  Then you could connect that to simple 6 position PV combiner with 15 or 20 amp CBI breakers to get that down to 2 wires to bring down to where the Classic is.

A MidNite product for this is the MNPV6

Make sure it has all of the breakers.   If the series fuse rating of the panels are 15 amps then 15 amp breakers will be fine.

Don't forget the PV disconnect that usually connects to the Classic PV input from the combiner positive output.  Six strings times 10 amps of short circuit current would be a 60 amp breaker but you have to add 25% on to that figure for NEC reasons (edge of cloud effects can bring that up) so an 80 amp breaker should work fine.

We have a string sizing program tool online that should verify all this but would also tell you the wire size for the 2 wires coming down from the combiner box.  Probably 8 gauge or maybe 6 gauge wire depending on how far that wire run is from the combiner to the Classic.  If less than about 50 feet then I think 8 AWG would be fine.  You might verify all this with the string combiner tool but it's close.

boB

[ClassicCrazy]

Here is the string calculator that Bob mentioned.
https://www.midnitesolar.com/sizingTool/index.php

Larry