The same Solar modules, different cable length

[tom14]

Hi,

i'm new to the forum. I'm trying to figure out how to connect 5x 410W panels.

I have 2x EPEver tracer 4210AN. It is MPPT and can handle 40A, 100V, max input is 1040W/24V(battery voltage system)

Panel speicification:
Max voltage Vmp: 38,80 V
Max Current Imp: 10,57 A
open circuit voltage Voc: 46,60 V
short circuit current Isc: 11,07 A

all panels are placed on the same west site 3 vertically 2 horizontally (should not matter?).

What is the best option for connection? 2 x 2 (parallel / seriell) to the first tracer and the last one alone to the tracer 2? It is better to connect the modules parallel (each two) and then this 2 strings seriell or first seriell and then parallel?

shall I take longer cables (max 6 meter distance) for each solar module and make the parallel / sequentiell connection in one place?

• positive: I have access to all module strings separatelly, can disconnect, test, reconfigure the modules.
• negative: need more cables/costs.
• Not sure: Is there any negative impact to the performance of the MPPT Tracer if the length of the cable differ by 1-2 meter?

or shall I make the configuration (sequentiell/parallel) directly under the solar Panels?

• positive: less costs/cables
• negative: for reconfiguration I need to dissamble modules, I cannot test the modules separatelly.

I hope, you could share your expirience, knowledge with me...

 

[time2roll]

Five? If all are to be connected they need to be all series or all parallel. With 100 Vmax on the controller I would be worried about 93.2 Voc with even a pair in series. So for me it would be all parallel and probably a second controller as the input could exceed 50 amps.

On edit... I see now there are two controllers. Yes all parallel due to the high Voc. 2 to the first and 3 to the second controller.

At 10 amps per panel I would probably pull individual wire for each panel to the controller. Possibly combine the pair and run a single #10 or #8 extension down to the controller. The 3 together are over 30 amps and would need a combiner box that I would try to avoid.

 

[MichaelK]

Is there any chance you can return the controllers, or perhaps sell them and upgrade to Epever's higher amperage models? You've kinda painted yourself into a corner with the purchase choices you've already made.

Assuming you de-rate panel performance to 85% what you will get with just three panels is {(410W X 3 panels)/26V charging} X 85% = 40.2A. that will max out one of the controllers. The second controller would be dealing with about 25-26A of current. All MUST be wired in parallel.

How cold are your winter lows? You can only wire your panels in parallel, because even just two in series will probably bump up the voltage past 100Voc on a cool, not even frosty morning. According to Midnite Solar's string calculator, you'll reach 100Voc at ~37 degrees F.

With a higher amperage controller, say the Tracer 8415, you could wire all five panels in parallel. You can not wire them in series unless you are willing to put aside one panel and wire them 2S2P.

Here is one thing you might try. Position three panels facing due south, wired in parallel to one controller, and position the other two panels either Southeast or Southwest with the second controller, again in parallel. I think most people need more power in the late afternoon rather than the early morning, so SW is what would work best for me.

 

[tom14]

Is the Max voltage Vmp: 38,80 V not to low for 24V Battery system? Let's formulate it in another way. Will the power output to battery be better if the panels are serial connected vs parallel? Will Prowse in his top 10 mistakes is speaking about minimal solar voltage needed for MPPT to start work...

I know 46,60 V * 2 = 93,2V is on the limit...

 

[tom14]

If I understand correctly the Rated charge power is a limited factor, so if could take another MPPT charge controller, then the Tracer10420AN is the only epever with 100A device that will work with 5x 410W solar panels and 24V Battery system?

Edit: I checked the prices. I already bought 2x epver for 2x 115EUR = 230EUR. Compare to this EPEver 10420AN costs 500EUR... Is there any advantage using Tracer10420AN vs 2x EPEver tracer 4210AN?

 

[Northernchateau]

Let me try a different approach and do Solar Math:

1st. 2 P configuration will work:
410 w panel x 2 = 820 w
Max voltage Vmp: 38,80 V x 1 = 38.80v
Max Current Imp: 10,57 A x 2 = 21.14 amps
open circuit voltage Voc: 46,60 V x 1 = 46.60 v
short circuit current Isc: 11,07 A x 2 = 22.14 amps

2nd 3 P will over panel the SCC watts by 18%:
410 w panel x 3 = 1230w
Max voltage Vmp: 38,80 V x 1 = 38.80v
Max Current Imp: 10,57 A x 3 = 31.71 amps
open circuit voltage Voc: 46,60 V x 1 = 46.60 v
short circuit current Isc: 11,07 A x 3 = 33.21 amps

3rd. 2 S configuration will work:
410 w panel x 2 = 820 w
Max voltage Vmp: 38,80 V x 2 = 77.6 v
Max Current Imp: 10,57 A x 1 = 10.57 amps
open circuit voltage Voc: 46,60 V x 2 = 93.2v

4th. 2S2P NOT Recommended as it will over panel your SCC watt by 58%:
410 w panel x 4= 1640 w
Max voltage Vmp: 38,80 V x 2 = 77.6 v
Max Current Imp: 10,57 A x 2 = 21.14 amps
open circuit voltage Voc: 46,60 V x 2 = 93.2v
short circuit current Isc: 11,07 A x 2 = 22.14 amps

My suggestion depends on your weather.
Above 60 degs F one wired 2P and one wired 3P
Below 60 degs F both wired 2P because the solar panel output voltage increases as temperature decreases.

 

[time2roll]

Is the Max voltage Vmp: 38,80 V not to low for 24V Battery system?

I know 46,60 V * 2 = 93,2V is on the limit...

Yes Vmp 38,8 is fine on 24v system.

Voc rises in cold temperatures. Depending on location I would keep Voc less than 80 to 90 volts with a 100v controller.

 

[tom14]

My suggestion depends on your weather.
Above 60 degs F one wired 2P and one wired 3P
Below 60 degs F both wired 2P because the solar panel output voltage increases as temperature decreases.

Hi, thank you for your math... After I have read from many information sources, I slowly understand the idea behind... Regarding to your math, I think you mean
1) Above 60 degs F: one wired 2S and one wired 3P and not "Above 60 degs F one wired 2P and one wired 3P"???
2) Below 60 degs F: you mean first:2P and second:3P and not "both wired 2P because the solar panel output voltage increases as temperature decreases."???

In warm days I could use 2S becouse the voltage will not be > 100V and in cold days it is saver then to switch to 2P...

Could somebody answer hopefully the last questions:
1) Is there any advantage using 2S vs 2P in warm days? If I understand correctly in warm days the voltage is lower and will not exceed 100V. In my case if the Vmp is 38,80 V and battery 24V, could 2S perform better becouse of more time the panels provide higher voltage > 24V and MPPT perform better? Or it is negligible?

2) At the and of the day I think it is better to use 2x EPever Tracer 4210AN vs 1x EPEver Tracer10415AN...

• 2x EPever 4210AN costs 240EUR can handle max 2x 1040W/24V (2P=820W < 1040W, 3P=1230. It is 15% oversized, but the tracker can reduce the power and there will be in rare cases PV 100% output.
• 1x Tracer10415AN can handle 100A 2500W/24V > 5x410W but the costs are about about 450EUR

Do you see any advantages using 1x Tracer10415AN for all 5 panels and pay double price?

 

[Pi Curio]

Hi,

i'm new to the forum. I'm trying to figure out how to connect 5x 410W panels.

I have 2x EPEver tracer 4210AN. It is MPPT and can handle 40A, 100V, max input is 1040W/24V(battery voltage system)

Panel speicification:
Max voltage Vmp: 38,80 V
Max Current Imp: 10,57 A
open circuit voltage Voc: 46,60 V
short circuit current Isc: 11,07 A

all panels are placed on the same west site 3 vertically 2 horizontally (should not matter?).

What is the best option for connection? 2 x 2 (parallel / seriell) to the first tracer and the last one alone to the tracer 2? It is better to connect the modules parallel (each two) and then this 2 strings seriell or first seriell and then parallel?

shall I take longer cables (max 6 meter distance) for each solar module and make the parallel / sequentiell connection in one place?

• positive: I have access to all module strings separatelly, can disconnect, test, reconfigure the modules.
• negative: need more cables/costs.
• Not sure: Is there any negative impact to the performance of the MPPT Tracer if the length of the cable differ by 1-2 meter?

or shall I make the configuration (sequentiell/parallel) directly under the solar Panels?

• positive: less costs/cables
• negative: for reconfiguration I need to dissamble modules, I cannot test the modules separatelly.

I hope, you could share your expirience, knowledge with me...

Hi Tom,

did you notice "Max. PV open circuit voltage:100V(at minimum operating environment temperature) 92V(at 25℃ environment temperature)" in the MPPT description?

If I didn't accidentally look into the wrong MPPT details, this MPPT is a no-go for connecting your panels in series.

You could try one SCC with 3p and the other one with 2P, 10AWG

 

[Northernchateau]

Hi, thank you for your math... After I have read from many information sources, I slowly understand the idea behind... Regarding to your math, I think you mean
1) Above 60 degs F: one wired 2S and one wired 3P and not "Above 60 degs F one wired 2P and one wired 3P"???
2) Below 60 degs F: you mean first:2P and second:3P and not "both wired 2P because the solar panel output voltage increases as temperature decreases."???

1. You can run either the 2s or 2p.
2. The reason I went with 2p and 3p is it avoid you going over voltage and then you are also setting up both arrays the same way.
3. As far as I understand there will not be a difference with 2p or 2s as you stay within the input limits when using an MPPT SCC
4.I would always recommend panels in series where possible as higher voltage and lower current reduces wire size and voltage drop.
5. As far as 1 controller or 2, I personally run 2 controllers as it gives me a back up if something happens to one of them or something else in the system.