A Forum run by Enthusiasts of MidNite Solar

Charge Controllers and Clippers => The "Classic" charge controller => Topic started by: russ_drinkwater on December 02, 2015, 05:22:15 AM

Title: 12 volt solar panels in 24 volt array
Post by: russ_drinkwater on December 02, 2015, 05:22:15 AM
I have 2 strings of 4 x 200 watt 12 volt solar panels connected to make a 24 volt input to my solar reg.
How do I calculate the wattage and amps that the reg should show? The panels as linked show 31.2 voc and 861 watts peal output.
This feeds into a 24 volt battery bank and then to a 3 kw latonics inverter.
Russ
Title: Re: 12 volt solar panels in 24 volt array
Post by: ClassicCrazy on December 02, 2015, 09:42:02 AM
Did you use the Midnite Solar string calculator ?
It will give you all the details that you probably want to know about the input.

http://www.midnitesolar.com/sizingTool/

I don't quite understand if you want to know what your Classic should be showing after they are connected ?

Larry
Title: Re: 12 volt solar panels in 24 volt array
Post by: zoneblue on December 03, 2015, 02:36:11 PM
Quote from: russ_drinkwater on December 02, 2015, 05:22:15 AM
I have 2 strings of 4 x 200 watt 12 volt solar panels connected to make a 24 volt input to my solar reg.
How do I calculate the wattage and amps that the reg should show?

As per your other thread those are 60cell panels, Vmp on the low side at around 28V. (60 cells normally run 30-32Vmp). They arent really "12 volt" panels. A "12 volt" panel is Vmp 17-18V. (Hence why we dont like the term "12 volt panel"). For the record "12 volt panels" are 17V Vmp so that they will work with a PWM controller into a 12v battery. You lose a couple of volts to panel heating, a volt in your cables, that leaves 14V for the asborb. With MMPT you need that plus a little more for the controller headroom.
Title: Re: 12 volt solar panels in 24 volt array
Post by: russ_drinkwater on December 05, 2015, 03:29:59 AM
The panels are 18 volt open circuit.