Classic 150 Charge controller to 48v bank # of panels max in wattage i can have installed

offgridcabin2015

Hello experts.

I"ll be purchasing this charge controler and i'm trying to figure out the max number of panels for an array i can have to it. 
wil be a 48v config.

I' know how to calculate the voc for in series but i'm a bit lost of how many strings i can have . IN other words
whatis the max total panel watts . 

I've attached a chart . but where i'm lost is the Vmp what's that?

So this is my train of thought.   300 watt panel voc is 39.61x 3 panels x 1.25 (cold factor) i'm still under 150vdc. Good here. This is string one.
so i think i can do 5 strings that bring me to 4500 watts? is that right? Based on chart below if i'm reading it right . i can do 4672watts at 80amps? Sure  that means i can have 15 panels on one array to this Classic 150 Charge controller and this even has  HyperVOC which extends VOC limits when needed.. so basically 150+48v (wiggle room for extreme cold) i feel i'm safe. 

Thoughts?

Vic

Hi o g c,

Have you used the MN Classic String Sizing Tool(?):

MidNite Solar - Classic Sizing Tool.

Busy now,  be back,  Vic

offgridcabin2015

Ty i'll see what i can learn from this tool. Ty for sharing.

Photowhit

offgridcabin2015 said:

Hello experts.

I"ll be purchasing this charge controler and i'm trying to figure out the max number of panels for an array i can have to it. 
wil be a 48v config.

I' know how to calculate the voc for in series but i'm a bit lost of how many strings i can have . IN other words
whatis the max total panel watts . 

I've attached a chart . but where i'm lost is the Vmp what's that?

So this is my train of thought.   300 watt panel voc is 39.61x 3 panels x 1.25 (cold factor) i'm still under 150vdc. Good here. This is string one.
so i think i can do 5 strings that bring me to 4500 watts? is that right? Based on chart below if i'm reading it right . i can do 4672watts at 80amps? Sure  that means i can have 15 panels on one array to this Classic 150 Charge controller and this even has  HyperVOC which extends VOC limits when needed.. so basically 150+48v (wiggle room for extreme cold) i feel i'm safe. 

Thoughts?

5 strings of 3 should be fine.

Not a copletely simple question, The Classic 150 can be 'overpaneled' without harm, and costeffective to use up to 20-30% more panels than normal, since panels tend to have a maximum output of about 75% of their panel rating.

All of thiis info is available at Midnites Classic sizing tool that Vic gave you a link to...

offgridcabin2015

So i did the tool but and i'll post the results here for my 10 panels but why does it show in red over voltage no matter if i choose 1 or 5 or 10 panels. That part makes no sense to me. 

Photowhit

offgridcabin2015 said:

So i did the tool but and i'll post the results here for my 10 panels but why does it show in red over voltage no matter if i choose 1 or 5 or 10 panels. That part makes no sense to me. 

There is no setup for 10 panels that works, not sure how you are plugging them into the tool. Due to your VMP and VOC only strings of 3 panels works. The voltage doesn't reach the 30% above working voltage for 48 volts for 2 panel strings and the VOC is too high for 4 panel strings.

I'd bet 5 strings of 3 panels should work and 6 strings of 3 panels should be too high, but cost effective (I don't think that's their words for it)

Vic

Agree with Photowhit,

Generally,  with Flooded Lead Acid (FLA) batteries in a 48 V system,  strings of two 60 Cell PVs has a too low string Vmp for these 150 V MPPT CCs,  strings of three are fine,   and strings of four PVs has excessive input voltage.

The thing about the Classic HyperVoc,  is,  that,  in this state,  the Classic goes to Rest  --  where it produces NO power,   until the temperature of the PVs increases,  which caused the Voc to be reduced.   It is great,  that the Classic is protected from damage of very high input voltage,  when in HyperVoc,  though.

Would run your PVs through the sizing tool,   but really would help to know your lowest temperature at the site.

Later,  Vic

littleharbor2

Vic said:

Agree with Photowhit,

Generally,  with Flooded Lead Acid (FLA) batteries in a 48 V system,  strings of two 60 Cell PVs has a too low string Vmp for these 150 V MPPT CCs,  strings of three are fine,   and strings of four PVs has excessive input voltage.

The thing about the Classic HyperVoc,  is,  that,  in this state,  the Classic goes to Rest  --  where it produces NO power,   until the temperature of the PVs increases,  which caused the Voc to be reduced.   It is great,  that the Classic is protected from damage of very high input voltage,  when in HyperVoc,  though.

Would run your PVs through the sizing tool,   but really would help to know your lowest temperature at the site.

Later,  Vic

Really surprised to see somebody disagrees with your post here. I, myself agree with  Vic and Photowhit.  Midnite controllers are the best built, robust and smartest controllers out there. Maybe just a typo.