Changing from 24v battery bank to 48v

solarhills99

I'm thinking of changing out a battery bank that was 24v to a new 48v either AGM carbon or lithium

Panels are 12v 4 in series VOC22 and VMP17.7

I'm running through Midnight charge controllers that can't take 8 panels wired in series. (easy rewire)

I know this is not ideal for 48v bank but can these work somewhat effectively to charge the bank?

Live in upstate NY, 90 degrees top summer, -15 in winter.

Thanks,

Charles

Photowhit

solarhills99 said:

I'm thinking of changing out a battery bank that was 24v to a new 48v either AGM carbon or lithium

Panels are 12v 4 in series VOC22 and VMP17.7

I'm running through Midnight charge controllers that can't take 8 panels wired in series. (easy rewire)

I know this is not ideal for 48v bank but can these work somewhat effectively to charge the bank?

Live in upstate NY, 90 degrees top summer, -15 in winter.

Thanks,

Charles

Run your panels through Midnite's sizing tool and you'll find that's really not enough voltage. Midnite likes 30% above the charging voltage, so you'd want to add to the strings of panels. Assuming lead acid charging up to 58 volts, and NOCT of around 17 VMP for the panels.

I guess you understand you'll need to replace the inverter too?

BB.

Agree with Photowhit's post... More or less, the Vmp-array needs to be around 80 volts to ~100 volts "ideally".

But that depends on temperatures (highs and lows), and if you have one of the "higher voltage" MPPT Midnite controllers or the standard 150 VDC max input.

Here is one link to the Classic string sizing tool that Photowhit typed about.

https://www.midnitesolar.com/sizingTool/index.php

As panel temperatures drop, Vmp and Voc rise. As the panels get hot, the Vmp and Voc voltage drop.

-Bill