Add more panels to system

[rmosborn]

I have a grid tie system. I have 8 , 315 watt panels on series and parallel. I run them through a combiner box. I have an extra breaker in the box and I would like to add 4 more 315 watt panels. I have a Radian 4048 grid tie inverter,
Is that possible if I find the same panels.
315 watt
9.4 amp
39 volts
To add more watts with no system changes?
Thanks

 

[sunshine_eggo]

"8 panels in series and parallel"?

4S2P?
2S4P?

What is the PV input current limit of the Radian?

 

[rmosborn]

"8 panels in series and parallel"?

4S2P?
2S4P?

What is the PV input current limit of the Radian?

I have 2 S and 2 P going in to combiner box
156 volts twice
156 to charge controller
I believe 200 limit into inverter
I was hoping to do one more set of 4 into one more combiner box breaker to get another 1260 watts for a total of 3780 watts

Hope that is enough info
Thanks

 

[sunshine_eggo]

I have 2 S and 2 P going in to combiner box
156 volts twice
156 to charge controller
I believe 200 limit into inverter
I was hoping to do one more set of 4 into one more combiner box breaker to get another 1260 watts for a total of 3780 watts

Hope that is enough info

Unfortunately, it is not, or it is not clear.

2S2P is 4 panels. You say you have 8, and you want to add 4 more. This doesn't make sense.

What is the PV input current limit of the Radian?

Do you have a separate charge controller? I can't find any data on the Radian being able to directly accept PV.

315 watt
9.4 amp (Isc)
39 volts (Voc)
To add more watts with no system changes?
Thanks

You're listing Voc and Isc?

If that's the case, it sounds like you have a 4S2P array. You say 156V into the controller, that's 4S * 39V = 156V.

Please provide the following:

1. Confirm you want to go from 4S2P (8 * 315W = 2520W) to 4S3P (12 * 315W = 3,780W)
2. Please provide a link to your charge controller's manual or datasheet OR
3. Please provide a link to your inverter's manual or datasheet.
4. Please provide a link to your solar panel's datasheet.

 

[rmosborn]

Sorry
I have two strings of 4 panels 2S and 2P
For a total of 8 panels
I have a midnite solar classic 200 feeding a Radian GS4048A grid tie up inverter
I put the panel array through a midnite MNPV6 PV combiner box currently using two breakers but have an extra breaker and spot in the box for one one.
That is why I was asking if I could add more watts same or less watt per panel
Thanks again for the replies

 

[rmosborn]

Goal is total 12 panels

 

[sunshine_eggo]

Sorry
I have two strings of 4 panels 2S and 2P

If you're seeing 156V at the controller, then you have 4S.

4S in parallel with another string of 4S

that's 4S2P

You want to be 4S3P.

For a total of 8 panels
I have a midnite solar classic 200 feeding a Radian GS4048A grid tie up inverter

Radian isn't relevant to the discussion.

Classic 200:

https://www.midnitesolar.com/pdfs/10-001-1_REV-V_Classic_Manual21FEB2023.pdf

78A * 48V = 3744W, which is greater than your proposed array.

No PV input current listed. 4S3P would be under 30A, so don't see a problem there.

I put the panel array through a midnite MNPV6 PV combiner box currently using two breakers but have an extra breaker and spot in the box for one one.

Have the same box. Assuming the plan is to pass a 4S string through a breaker; 3 strings, 3 breakers.

That is why I was asking if I could add more watts same or less watt per panel

I don't understand this at all.

Thanks again for the replies

I see no issues.

You can confirm for yourself here:

MidNite Solar - Classic Sizing Tool.

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

Since you didn't provide the requested information, I guessed at the panel values:

 

[rmosborn]

If you're seeing 156V at the controller, then you have 4S.

4S in parallel with another string of 4S

that's 4S2P

You want to be 4S3P.




Radian isn't relevant to the discussion.

Classic 200:

https://www.midnitesolar.com/pdfs/10-001-1_REV-V_Classic_Manual21FEB2023.pdf

View attachment 142279

78A * 48V = 3744W, which is greater than your proposed array.

No PV input current listed. 4S3P would be under 30A, so don't see a problem there.



Have the same box. Assuming the plan is to pass a 4S string through a breaker; 3 strings, 3 breakers.



I don't understand this at all.



I see no issues.

You can confirm for yourself here:

MidNite Solar - Classic Sizing Tool.

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

Since you didn't provide the requested information, I guessed at the panel values:

View attachment 142280

If you're seeing 156V at the controller, then you have 4S.

4S in parallel with another string of 4S

that's 4S2P

You want to be 4S3P.




Radian isn't relevant to the discussion.

Classic 200:

https://www.midnitesolar.com/pdfs/10-001-1_REV-V_Classic_Manual21FEB2023.pdf

View attachment 142279

78A * 48V = 3744W, which is greater than your proposed array.

No PV input current listed. 4S3P would be under 30A, so don't see a problem there.



Have the same box. Assuming the plan is to pass a 4S string through a breaker; 3 strings, 3 breakers.



I don't understand this at all.



I see no issues.

You can confirm for yourself here:

MidNite Solar - Classic Sizing Tool.

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

Since you didn't provide the requested information, I guessed at the panel values:

View attachment 142280

Sunshine you are correct
I relooked at my solar diagram.
Final question.
What are my limits on additional panels? As long as I stay below 3780 do I need to look for 39 volt panels and 9 amp but a different panel wattage.
Just not sure I will be able to match the panel stats
I thought I had pasted the specs.

 

[sunshine_eggo]

Sunshine you are correct
I relooked at my solar diagram.
Final question.
What are my limits on additional panels? As long as I stay below 3780 do I need to look for 39 volt panels and 9 amp but a different panel wattage.
Just not sure I will be able to match the panel stats
I thought I had pasted the specs.

For another string in parallel, the series Vmp needs to be as close as possible, at least no worse than 5-10%. The array will run somewhere in between the two Vmp values (usually closer to the lower), and you can expect a 5-10% penalty to the entire array (all strings).

If you end up mixing in series with your other panels, you will need to match the 9.44 max power current (Imp). Panels in series will operate at the LOWEST rated panel at all times.

The "-60" indicates 60 cell panels, so you will have the best luck searching 60 cell panels.

 

[rmosborn]

Sunshine I am having trouble finding panels that are close to current panel specs.
I am trying to understand your last help. What if I found 320 or 350 watt panels with 9 + amps and 37+ volts and just lose the watts? I believe you said system would operate at the lowest rated panel which would be 315. If I understand I might be willing to except that to get me more watts in total to max out inverter
thanks for your time. I am not in a hurry just really enjoying the watts I am generating to offset our usage and want some watts During the summer
thanks

 

[sunshine_eggo]

Watts doesn't matter much.

In series, you want the same Imp. All panels will operate at the current of the lowest rated panel - current - not power.
In parallel, you want the same voltage. All panels will tend to operate at the lower Vmp.

 

[rmosborn]

Sunshine. Happy US Memorial Day.
still looking for a new string. I have about 1250 watts left on my 4000 watt inverter. I am finding panels for 37 volts. Current panels are about 39. I am sending about 150 volts to a combiner box. Will the lose be significant if I add 37 volt panels? I am almost inclined to just replace all panels so they match.
I am really pleased with my backup system. I am generating about 11 to 12 killo watts per day here in north Texas.
what would you suggest?

thanks

 

[rmosborn]

Good morning Sunshine.
Still looking for panels.
Based on what you said above, I believe I have found 4 panels to as close as I can to current panels.
Old panels 39.61 volts, new panels 40.3
I believe the IMP is 9.44 old and 9.7 new.
It is less than 2% difference.

Will you take a look and confirm what I am seeing.

Thanks again.

 

[sunshine_eggo]

Good morning Sunshine.
Still looking for panels.
Based on what you said above, I believe I have found 4 panels to as close as I can to current panels.
Old panels 39.61 volts, new panels 40.3
I believe the IMP is 9.44 old and 9.7 new.
It is less than 2% difference.

Will you take a look and confirm what I am seeing.

Thanks again.

Those numbers are well matched. Would expect no more than a 3% total penalty on the rated array power.

 

[rmosborn]

Thanks again sunshine for confirming.