Schneider Conext 100a Charger Controller wiring help please

[hammick]

Our 2.6 kw roof array has been damaged by wind and insurance has paid out. I have ordered an Iron Ridge ground mount that can hold 12 Q-cell 360w panels. I just ordered 12 panels but am considering changing to nine panels for wiring simplicity. 9 panels will give me 630 more watts than I currently have plus a much better winter angle with the ground mount (18 degrees for current roof mount vs. 35 degrees for ground mount).

I have been told that with Schneider's 100a charge controller that I can put 9 360 watt panels in series with a 14 gauge wire run to the charge controller and be fine. However, I want the option down the road to expand the system to 12 panels (2 strings of 6) and use the same wiring to the charge controller.

I was told the 100a CC has three different inputs that are in parallel to each other. I have no desire to have two 100' wire runs.

If I want to have 2 strings of 6 in the future can I just put a combiner box at the ground mount with one wire run to the CC just like my current 60a Schneider controller?

If this works what size wire should I use (assume it will be in liquid tight conduit).

Thanks.


PS: I have to stick with Schneider because I have remote configuration/monitoring working just the way I need it.

 

[sunshine_eggo]

If I want to have 2 strings of 6 in the future can I just put a combiner box at the ground mount with one wire run to the CC just like my current 60a Schneider controller?

Maybe.

What is the input current limit on a single MPPT connection? It may prohibit 2P.

If this works what size wire should I use (assume it will be in liquid tight conduit).

Calculate your voltage drop for distance, 6X Imp and 2X Isc

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

estimated resistance tab.

Pick a wire gauge that results in 3% or less loss.

 

[hammick]

Maybe.

What is the input current limit on a single MPPT connection? It may prohibit 2P.



Calculate your voltage drop for distance, 6X Imp and 2X Isc

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

estimated resistance tab.

Pick a wire gauge that results in 3% or less loss.

Do you mean short circuit current or current at MPPT? Here are the specs from the CC and panels. Thanks.


MPPT 100 600 Electrical Specifications
Nominal battery volatage 24 and 48 VDC
PV array operating voltage 195 to 550 V
MPPT voltage range 195 to 510 VDC
Max PV array open circuit voltage 600 V including temperature correction factor
Battery voltage operating range 16 to 67 VDC
Max. array short circuit current at STC 35 A
Max. charge current 100 A
Max. and min. PV wire size in conduit #6 AWG to #14 AWG (13.5 to 2.5 mm2 )
Max. output power 6000 W (nominal 48 V systems)
Charger regulation method Three-stage (bulk, absorption, float) plus manual equalization Two-stage (bulk, absorption) plus manual equalization Supported battery types Flooded, GEL, AGM, Lithium-ion, Custom

 

[sunshine_eggo]

Do you mean short circuit current or current at MPPT? Here are the specs from the CC and panels. Thanks.


MPPT 100 600 Electrical Specifications
Nominal battery volatage 24 and 48 VDC
PV array operating voltage 195 to 550 V
MPPT voltage range 195 to 510 VDC
Max PV array open circuit voltage 600 V including temperature correction factor
Battery voltage operating range 16 to 67 VDC
Max. array short circuit current at STC 35 A

35A should allow 3P

use the following in the voltage drop calculator:

6X 33.89V
2X 10.62A

A wire size that results in 3% or less in losses is good.

 

[hammick]

I spoke with Schneider tech support and they told me I could put 12 360w panels in series on their 100a Charge Controller. He said the charge controller goes into standby fault mode at 550 volts and clears the fault when voltage drops to 540 volts. He said the CC won't fry unless it sees 600 volts. I am hoping you guys who are a lot smarter than me can double check my math and clue me into anything I might be missing. I used an online calculator. Thanks.

Solar panel wattage =360w
Battery bank voltage = 48v
Estimated low temp = negative 20 degrees Fahrenheit
Panels STC = 25 degrees Celsius
Panels VOC = 41.2
Panel IMP = 10.62
Temp Coef of VOC = negative .27
Temp Coef of Pmax = negative .35
Panels in series = 12
Parallel strings = 1

Max volts per panel at negative 20 degrees Farenheit = 47.1946
Array max voltage at negative 20 degrees Farenheit = 566.3352
Max amps to charge controller = 10.62
CC max amp output = 104.42



The reason I want to put 12 in series verses 2 strings of 6 is wire size. We are going to try to route the wire under the sidewalk surrounding my building so I don't have to cut concrete.

My calculations are showing 14 gauge wire will work for a 100' run at 1% loss. I'll probably use 12 gauge though.

 

[sunshine_eggo]

Looks about right. I didn't check your math, but there's about an 8% voltage increase between 25°C/77°F and freezing. You're about about a 15% change.

 

[JBertok]

You can combine multiple series strings into a Schneider MPPT's single input. This is exactly what I'm doing with all four of my MPPT 60-150 controllers, each with 6 strings of 3 panels. Every string needs a blocking diode installed inline or the MPPT functions won't work right. Inline diodes with MC4 connections are available on Amazon and they're cheap.

 

[hammick]

Thanks for the all the advice guys. I'm going to connect all 12 panels in series and probably use Southwire 12/2 direct burial wire. I have a couple questions.

I was planning on putting a Square D 30 amp 120/240v NEMA 1 rated disconnect where the array wiring enters the building. The disconnect is a lever throw type and will be mounted inside. Can I use this type of disconnect for high voltage DC wiring or is arcing a concern? I already own it but if it's not a good idea I will spend the $$$ for a 600v DC disconnect.

Is there any reason to have a disconnect outside at the ground mount array? I was planning on using the Midnight Solar combiner box that I already own for the wiring from the panels to the 12/2 wiring to the building and putting a 600v Midnight Solar surge protector on it. It won't have any breakers or fuses. I can't think of any reason for a disconnect at the array. We are off grid, remote and outside of any code jurisdiction.

Since I will be using a grounding rod as required by Iron Ridge I'm guessing grounding the array to my solar equipment and main breaker panel is a bad idea? I won't use the grounding conductor in the 12/2 direct burial wire.

I plan to cover the panels with blankets or cardboard when making the electrical connections for added safety.

I need to figure out what type of breakers to use for the charge controller. I'll be using Schneider's new 600v CC.