48v vs 24v

[labusker]

I am looking to set up a 24 or 48v battery bank system, whichever is better for the Classic 150 to operate at. Total panel watts = 2600w (I am limited to 8 panels). Input to the Classic will be 81V voc and 41A Isc. A 48v system will give me a nominal 54A out. A 24v system will give me a nominal 108A out, but limited to 96A. If at 48v, is 81V voc high enough to maintain battery equalization? If at 24v, is the 96A continuous too hard on the classic causing too much heat? I would prefer the 24v system because it can be managed easier when adding or subtracting batteries.

[mike90045]

I'd suggest 48V.   Smaller battery cables, everything in a series string. 

[ClassicCrazy]

Not the  best to add batteries to a system later on since it is best to have all batteries the same age ( lead acid ) . So better to do whatever batteries you choose the best for your needs at the beginning.

Larry

[boB]

I think that the Classic 150 will current limit before 96 amps output on a 24V battery.

96 amps, if I remember correctly is for  12V battery.    Not sure what the limit is for 24V but yeah, you might be running it close  or current limiting a lot of the time if you have enough sun. 

48V should ensure better usage of your array I think.  Either way, if you can connect your batteries that WOULD have been used for 24V, then you still have the same energy storage for either system.

You can sure try 24V though.  It's just that if you buy and install 24V inverter(s) then that would have to be changed out.

[Vic]

Hi lab..,

Here is a Classic Power Comparison Chart:
http://www.midnitesolar.com/images/classicFrontPage/graphs.php

Would guess that you might be considering using the LG Neon 325 W PVs.  These,   or any similar 60 Cell Pvs  will not have sufficiently high String Vmps,   in strings of two PVs,   for a 48 V battery,   particularly a Flooded LA battery.

At 24 V,  strings of two should be fine with MPPT Charge Controllers,   like the Classic.

Strings of three PVs would be fine with a 48 V FLA battery,   but,   this would not work well,   trying to maximize power production,   with only 8 PVs.

You can use the Classic String Sizing Tool,  with your exact PVs to get a better idea of what you might expect,   be sure to look at the Notes at the bottom of the Sizer's form.

String Sizer:
http://midnitesolar.com/sizingTool/index.php

FWIW, Vic

[qrper]

 I guess you could use a 72 cell panel as well, to provide the extra kick for 2 panels in series for a 48 v system. provided you haven’t already purchased your solar panels.
  Is there a reason why you are limited to eight panels?

Mike