Needing a wiring diagram : looking to wire in a 2nd MPPT 40amp controller into system.

offgridcabin2015 · December 2020

Hey peeps. i'm looking to draw on your expert experiences to wire in SRNE (ML2440) 40 Amp MPPT Charge Controller.

Note there is no more room on battery bank posts to run thick wires from charge controller to batts. Yes i can flatten a copper pipe and tap and die holes and thread in bolts and make my own Neg / and POs Bus bars, but i feel you folks have a cleaner and more efficient wiring method.
As always, Thankyou to all that you do.

Neil.

Photowhit · December 2020

offgridcabin2015 said:

Hey peeps. i'm looking to draw on your expert experiences to wire in SRNE (ML2440) 40 Amp MPPT Charge Controller.

Note there is no more room on battery bank posts to run thick wires from charge controller to batts. Yes i can flatten a copper pipe and tap and die holes and thread in bolts and make my own Neg / and POs Bus bars, but i feel you folks have a cleaner and more efficient wiring method.
As always, Thankyou to all that you do.

Neil.

If you are getting to the point of needing a 2nd charge controller, you really should start thinking about a breaker box.

1 connection to the battery bank and then every thing connected to busbars in the breaker box.

Here's a diagram of the incoming solar array's from behind the box at the top;

Image: https://us.v-cdn.net/6024911/uploads/editor/yb/0w42yg10tw2v.jpg

Here's mine, an E-Panel. The heavy wires are going to the battery bank, the circled blue bus bar is negative and the red is positive. I have 2 charge controllers off to the right.

Here's a picture of the setup overall, with the original inverter from my previous cabin.

offgridcabin2015 · December 2020

Thankyou Photowit ( dec 22 2020).

I"m trying to follow the wiring so i can somone copy it. i'm thinking i can just create a bus bar and perhaps have to breakers one for each charge controllers 40amp and 80 amp .

I think i may of found the weakness point in my solar arrays. I have one array ( 5x200watts) panels. So i'm thinking all other panels ( 2 other array (array# 1( 4( 250watts) ) + (array #2 (2x300wats) well be to that spec? for they are all ON THE SAME CHarge conroller. Right? So the charge controller see all arrays only at 200watt for the sum of all panels?

I"m thinking i can take 3* 300 watts solar panels to one charge controller / 40amp, it caps out at 1100 watts to it's own charge controller that should net me MORE solar?

Question am i right on that?

Photowhit · December 2020

offgridcabin2015 said:
I"m trying to follow the wiring so i can somone copy it. i'm thinking i can just create a bus bar and perhaps have to breakers one for each charge controllers 40amp and 80 amp .

I added some photos so you could better understand the setup.

You can buy insolated busbars at most electric supply places, Arizona Wind and Sun has them as well;

Outback Power Red Insulated Terminal Bus Bars | Northern Arizona Wind & Sun (solar-electric.com)

offgridcabin2015 said:
I think i may of found the weakness point in my solar arrays. I have one array ( 5x200watts) panels. So i'm thinking all other panels ( 2 other array (array# 1( 4( 250watts) ) + (array #2 (2x300wats) well be to that spec? for they are all ON THE SAME CHarge conroller.

Not sure what you are asking?
I took a quick look at your charge controllers spec's, Looks like a "Epever" SRNE (ML2440) 40 Amp MPPT Charge Controller. You want to be sure the panels fit the specs and not go over even during the coldest days of winter.

As I read the spec's it won't work for a single additionale charge controller, if you have "... 4( 250watts) ) + (array #2 (2x300wats)..."

But looks like you want to add 2 more? Really can't understand what you are asking.

Basically need some more info about the charge controllers and system voltage and the solar panels you'd like to connect.

littleharbor2 · December 2020

Ditto what Photowhit said. Watts are meaningless when trying to configure your array. We need the Voc. and Vmp. from the data tags on the rear of all the panels and a better description as to what you are trying to do.

offgridcabin2015 · December 2020

Thanks so much for the photo's (helps me alot better) ( Dec 23 2020)

NOw i'll try to give clarity to what i[m asking . if a man has 3 solar arraysa att at dirrent wattages (like i do) , i belive the charge controller see it as the wattage of the LOWEST wattage . correct? which mean i need to put the each array on it's own charge controller.

so for example array one> all 200watt panels 5 panel is 1000watts + array 2 > 4-250 panels which is also 1000 watts , and array # 3 (2-300watts) . but i feel the charge conroller only see's 800 of the 1000 watts. Am i making any since here? for it see' all panels as 200 watts /Reason being is they are all on the same Charge controller.. ( i hope that comes across clearly / makes sense)

BB. · December 2020

With the array, there is no Wattage issue (at least at this point--Yes, the controller ultimately has a limit to how much wattage it can feed into the battery bank--But it does not "take power" from only one array or the other because of wattage).

It is the specific Voltage and Current ratings of the solar panels (and the amount of sun hitting the panels at any instant in time) that will "steer" the solar panel current from string A, B, and/or C.

Can you tell us the specific Vmp/Imp of each solar panel... And how you have them wired? I.e. (note that "strings" are a single set of solar panels wired in series. Parallel are those strings of 1-x series strings of panel connected together in parallel):

String A: Vmp=18v / Imp = 8 amps; 3x panels in series on MPPT charge controller 1
String B: Vmp=30v / Imp = 4 amps, 2x panels in series on MPPT charge controller 1
String C: Vmp=36v / Imp = 5 amps, 1x panel on PWM charge controller 2
Battery bank: 24 Volt @ 200 AH @ flooded cell lead acid battery bank

What is confusing us is your Array configuration vs Charge Controller connection(s)... MPPT controller control the array differently vs PWM charge controllers.

More or less, each string of panels has to "match" Imp within 5-10% or better (i.e., 10 amp panel + 11 amp panel in series)

Paralleling series string into one array must match Vmp-string within 5-10% or better (i.e., Vmp-string A 35 volts in parallel with Vmp-string B 37 volts), etc...

Until we get this ironed out, don't worry about Watts just yet. It is like light bulbs--You can have a 7 Watt night light + 13 Watt LED + 100 Watt filament lamp all on one 120 VAC circuit in parallel--They all light independently of each other--The "wall switch" does not care about the individual bulbs.

-Bill

Needing a wiring diagram : looking to wire in a 2nd MPPT 40amp controller into system.

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