Amp limit reached. Why?

[Aquaponic Machine]

Hello I have a classic 250 and I put 2 strings of 5 panels in series the panels are 250w each... I have each string on 15 amp brakers and the 24v battery on a 60amp braker....

With only one string the classic is reading 46 amps and when I put on the other string it is reading amp limit is this ok?

Should I wire them differently?

[ClassicCrazy]

Did you use the Midnite string calculator ?
It will show you if your design is okay and also you can see other options to wire them up differently.
Since the Classic 250 amp limit is 62 amps it sounds like you have reached the limit of the output .
From what I understand the Classic can handle some over amps - but I am not quite sure - there are past discussions about this on the forum .
If you want to get full power from your PV you may need to either get a second Classic 250  or a Classic 150 that may be able to handle all you present PV . If using a Classic 150 you would need to change the 60 amp breaker to 100 amp and also any associated wiring to size for that.
Best to run some things through the Midnite string calculator .
http://www.midnitesolar.com/sizingTool/displaySizing.php
Do you have a Classic 250 because you need to run a higher voltage input ?

Larry

[Vic]

Hi Aqua ..,

Welcome to the Forum.

As Larry mentioned the Classic String Sizer  is a very useful tool for designing a PV power system.

Also,  please look at the graphic in the following Link:
http://www.midnitesolar.com/images/classicFrontPage/graphs.php

It looks like the outdoor temperature was cool,  when you noted seeing about 45 A (output current)  from the Classic 250.

The Classic 250 appears to be a bit overloaded,   and when the Classic Limits output current,   this indicates that come of the power from the PVs is not being used.   The output current can be further Limited if the Classic's temperature increases above about 40 degrees C.

The ratio between the PV voltage into the Classic verses the battery temperature will increase the Classic's operating temperature,   a bit.   Heating in the Classic can reduce its output current capability,  as noted above.

With strings of five PVs you would probably not be able to use a Classic 150.   Most 250 W PVs  have a Voc of about 38 V,  or so (guessing).   This would give an STC string Voc of about 190-ish V.

Five strings of two PVs would probably be OK with a Classic 150 (have not run this through the Sizer),   but you currently have the 250,  so that may not be in the cards.

FWIW,   Vic

[boB]

I wonder how much it is actually limiting ?  Do you see the limit all day pretty much and every day ?

Maybe you are just on the edge of limiting  now ?

boB

[FNG]

10 modules is 2500 watts divided by 25 volts gives you the potential of 100 amps charge current, So with a classic 250 it will limit to about 62 amps so the fact you see 46 amps with one string would tell us you have about 92 amps of current available. You are likely limiting by 30 amps most of the peak of the day. If the energy is needed I would suggest 2 Classics for this install

[Beyla]

I would not exceed three panels on a string with the Classic 150, if you take Temp extremes you might get yourself in trouble by exceeding the 150 volts. Ie: 37x3 = 111 volts. 37x4= 148 ... too close for comfort and stressing the Classic 150.