Can I add more PV panels, w/o damaging the charge controller?

[pvdude]

First time DIY solar, has been running fine since I turned it on in May.

I have learned that the actual output of the PV array @ the Charge Controller is less than the published numbers, due to normal system losses.
Charge Controller is the 100A- 600vdc version of this:

Conext MPPT 100 600 Charge Controller

The Conext MPPT Charge Controller offers optimum system performance for solar installations, with flexible installation of large PV arrays.

solar.schneider-electric.com

It maxes out @ 6kw.
Spec sheet says “allowance for over-sized arrays”, whatever that means???

There are two strings of 8 - 365watt panels, (REC 365AA) for a total of 5840 watts.
I have never seen more than 5200 watts, as per the losses.

Too many clouds here in Summer, so the efficiency and charge rate of the batteries suffers.
But if I had more PV, charge rate would be fine, even w/ clouds.

I can add 3 more panels to each string, (total - 11 per) and still stay within the voltage limit of 550VDC.
Not sure what the Winter temperatures will do to the 44.0 voc.
It can get into the 30’s here for a couple of hours, on the coldest day of Winter, just before sunrise.
Will know in about 5 months from now.

11x44.0voc = 484vdc.
12x44.0voc = 528vdc, too near the limit.

But 11x365watts is 4015watts per string, total of 8030 watts.
Not sure how to estimate the system losses, but if I use 11%, the Charge Controller could still see 7100watts.

Do you think this is OK, or will every molecule in the CC explode @ the speed of light?

 

[anadiner]

The allowance... is referring to whats called 'boost...' but dont concern urself cuz n/a to this situation.

Appears u have the voc criteria worked out. Just leaves amp allowance/limitation.

 

[Bud Martin]

Typicaly you will factor in +15% (or more based on spec of the panel) higher VOC for low temperature.
11x44.0voc = 484vdc. So 484V factor in +15% = 556V
12x44.0voc = 528vdc. So 528V factor in +15% = 607V

"Spec sheet says “allowance for over-sized arrays”, whatever that means?"
It means you can have panel power over 6KW to feed the SCC, it is helpful to overpanel so you can still get good power in cloudy and at longer period of time during the day if you arrange the panels so they can collect the power through out the day not just at peak time.

 

[MisterSandals]

But 11x365watts is 4015watts per string, total of 8030 watts.
Not sure how to estimate the system losses, but if I use 11%, the Charge Controller could still see 7100watts.

What is your battery voltage?
if 25.6V then 7100W / 25.6V = 277A
if 51.2V then 7100W / 51.2V = 138A

Either way, your SCC will only charge at 100A so worrying about system losses is moot. You're leaving a LOT of power out there by not having enough SCC.

What you could do would be to point one array east-ish to start charging earlier (and with half the array, half the amps) and one array west-ish to charge later in the day.
By charging longer (2x?), you will make better use of your undersize SCC by using it for longer periods.

 

[Fusion is the future]

What is your battery voltage?
if 25.6V then 7100W / 25.6V = 277A
if 51.2V then 7100W / 51.2V = 138A

Either way, your SCC will only charge at 100A so worrying about system losses is moot. You're leaving a LOT of power out there by not having enough SCC.

What you could do would be to point one array east-ish to start charging earlier (and with half the array, half the amps) and one array west-ish to charge later in the day.
By charging longer (2x?), you will make better use of your undersize SCC by using it for longer periods.

 

[Fusion is the future]

First time DIY solar, has been running fine since I turned it on in May.

I have learned that the actual output of the PV array @ the Charge Controller is less than the published numbers, due to normal system losses.
Charge Controller is the 100A- 600vdc version of this:

Conext MPPT 100 600 Charge Controller

The Conext MPPT Charge Controller offers optimum system performance for solar installations, with flexible installation of large PV arrays.

solar.schneider-electric.com

It maxes out @ 6kw.
Spec sheet says “allowance for over-sized arrays”, whatever that means???

There are two strings of 8 - 365watt panels, (REC 365AA) for a total of 5840 watts.
I have never seen more than 5200 watts, as per the losses.

Too many clouds here in Summer, so the efficiency and charge rate of the batteries suffers.
But if I had more PV, charge rate would be fine, even w/ clouds.

I can add 3 more panels to each string, (total - 11 per) and still stay within the voltage limit of 550VDC.
Not sure what the Winter temperatures will do to the 44.0 voc.
It can get into the 30’s here for a couple of hours, on the coldest day of Winter, just before sunrise.
Will know in about 5 months from now.

11x44.0voc = 484vdc.
12x44.0voc = 528vdc, too near the limit.

But 11x365watts is 4015watts per string, total of 8030 watts.
Not sure how to estimate the system losses, but if I use 11%, the Charge Controller could still see 7100watts.

Do you think this is OK, or will every molecule in the CC explode @ the speed of light?

split up your solar area and take a second charger controller of 100 A

 

[MisterSandals]

split up your solar area and take a second charger controller of 100 A

If battery voltage is 25.6V, then it'd take 3 SCC's. More info about the system would help.

 

[Fusion is the future]

If battery voltage is 25.6V, then it'd take 3 SCC's. More info about the system would help.

I would go for sure for 48V / 51V, rearrange the batteries .
Half the amps and a lot less lost

 

[pvdude]

Battery voltage is 48vdc.
CC typically delivers about 53vdc.
I have seen an instantaneous peak of 95A @ 53vdc.
Rolls said to limit the charge rate to about 80% (445Ah of FLA).
However, the system seems to self limiting.
When the Sun comes up, the charge rate slowly ramps up.
During the day, the PV energy goes to the load, and the batteries are not used.
Except.
When clouds shadow the PV, the inverter takes energy from the batteries to make up for the missing PV energy.
After the clouds pass is interesting, after lowering the battery capacity during the shade, when the PV gets hit w/ full Sun, it spikes to 5kw for a few seconds, and then ramps down as the batteries fill.

I’m hoping that adding more PV will let the CC obtain enough energy during shade so as to avoid the big inrush spikes.
I realize adding more PV panels than the CC can use seems wasted, but if the average PV output, under cloud, is raised a bit, seems like it would help.
I just hope to flatten out the spikes, and gain more PV output during clouds.
I like the idea of another array facing West, but not sure how much that would help during the cloud power attenuation cycles.

 

[pvdude]

The system consists of a Schneider XW Pro+ inverter, Schneider 100A-600vdc MPPT charge controller, 8 Rolls S6 L16-HC 6 volt 445Ah batteries for 48vdc, some Schneider control electronics & monitoring equipment.
The inverter is rated @ 6800watts continuous, 8500watts for 30 minutes, 12000watts for 30 seconds.

 

[Fusion is the future]

Battery voltage is 48vdc.
CC typically delivers about 53vdc.
I have seen an instantaneous peak of 95A @ 53vdc.
Rolls said to limit the charge rate to about 80% (445Ah of FLA).
However, the system seems to self limiting.
When the Sun comes up, the charge rate slowly ramps up.
During the day, the PV energy goes to the load, and the batteries are not used.
Except.
When clouds shadow the PV, the inverter takes energy from the batteries to make up for the missing PV energy.
After the clouds pass is interesting, after lowering the battery capacity during the shade, when the PV gets hit w/ full Sun, it spikes to 5kw for a few seconds, and then ramps down as the batteries fill.

I’m hoping that adding more PV will let the CC obtain enough energy during shade so as to avoid the big inrush spikes.
I realize adding more PV panels than the CC can use seems wasted, but if the average PV output, under cloud, is raised a bit, seems like it would help.
I just hope to flatten out the spikes, and gain more PV output during clouds.
I like the idea of another array facing West, but not sure how much that would help during the cloud power attenuation cycles.
View attachment 63388

It looks to me that you controler charger start to soon by a to low area voltage, normal is to start at 70 % of the area voltage that is why you have so an iregualar charge patron, my 10 cents
Can you adjust that ?
I know that in my Flexmax 80 i can change it .
You need an overhead between your area voltage to start charging and the battery voltage

 

[Fusion is the future]

The system consists of a Schneider XW Pro+ inverter, Schneider 100A-600vdc MPPT charge controller, 8 Rolls S6 L16-HC 6 volt 445Ah batteries for 48vdc, some Schneider control electronics & monitoring equipment.
The inverter is rated @ 6800watts continuous, 8500watts for 30 minutes, 12000watts for 30 seconds.

Schneider is quality stuff, see my other comment .

 

[pvdude]

The MPPT CC starts charging the batteries when there is enough light to produce 195vdc from the PV array.
That is a good thing, I want it to charge the batteries!

 

[Fusion is the future]

It looks to me that you controler charger start to soon by a to low area voltage, normal is to start at 70 % of the area voltage that is why you have so an iregualar charge patron, my 10 cents
Can you adjust that ?
I know that in my Flexmax 80 i can change it .

The MPPT CC starts charging the batteries when there is enough light to produce 195vdc from the PV array.
That is a good thing, I want it to charge the batteries!

That seems to me a bit high for an 48 Volt system , what is your open area voltage according the specs ? start at 70 % from that voltage.
how much panels , how much in serial and how much strings parallel , specs from the panels ?

 

[anadiner]

The allowance... is referring to whats called 'boost...' but dont concern urself cuz n/a to this situation...

Appears u have the voc criteria worked out. U didnt mention amp allowance/limitation. U may have ran panels in series to keep amps low hence higher voltage and yes gotta watch limit doing it that way.

Speaking of, u could try adding panels parallel which wouldnt affect voltage. I assume u r aware to keep ur panel voltage higher than batteries. Ur using MPPT which gives u more leeway than some repliers r accounting for.

So Im saying, ur doing awesome watching voltage limitation. I do not recommend pushing the limits cuz cloudy etc... if ur close and want to add, play around with adding in parallel.

 

[Fusion is the future]

I have 5 string of 3 panels, area voltage is 114 V, MPPT Charger/controller wake up at 70% =78 V plenty of headroom for a 48 V system

 

[pvdude]

Thanks very much for all the great ideas & tips!
Looks like I need to add more parallel strings.
Currently have two 8S, soon to become two 11S.
The 11S upgrade will produce somewhere between 7-8kw @ about 480vdc = about 16A from the PV to the CC.

The CC can accept up to 29A from the PV array;


My goal is to have enough PV so as to allow the inverter to operate near the 6800watt continuous limit specification.

No idea how to position a second PV array facing West, all I can find is info on locating Solar South, and insolation maps for South facing.
Is there a “Solar West” chart somewhere?
Red bar in photo would be the possible location for a West-facing PV array.

 

[Fusion is the future]

Thanks very much for all the great ideas & tips!
Looks like I need to add more parallel strings.
Currently have two 8S, soon to become two 11S.
The 11S upgrade will produce somewhere between 7-8kw @ about 480vdc = about 16A from the PV to the CC.
View attachment 63430
The CC can accept up to 29A from the PV array;

View attachment 63431
My goal is to have enough PV so as to allow the inverter to operate near the 6800watt continuous limit specification.

No idea how to position a second PV array facing West, all I can find is info on locating Solar South, and insolation maps for South facing.
Is there a “Solar West” chart somewhere?
Red bar in photo would be the possible location for a West-facing PV array.
View attachment 63432

http://greenerenergy.ca/PDFs/Tilt%20and%20Angle%20Orientation%20of%20Solar%20Panels.pdf

Solar Panel Angle Calculator: The Definitive Guide - Today's Homeowner

Installing solar is a significant investment. Whether you’re a homeowner looking to spend a few thousand dollars, a business looking at a system

www.semprius.com

put 3 panels in a string for the right voltage and make more strings, parralel is BETTER !

 

[anadiner]

http://greenerenergy.ca/PDFs/Tilt%20and%20Angle%20Orientation%20of%20Solar%20Panels.pdf

Solar Panel Angle Calculator: The Definitive Guide - Today's Homeowner

Installing solar is a significant investment. Whether you’re a homeowner looking to spend a few thousand dollars, a business looking at a system

www.semprius.com

put 3 panels in a string for the right voltage and make more strings, parralel is BETTER !

Find west chart then pls pass it on. The face South thing is pushed here but I still lean on side each is diff case.

My house position is this crazy west to east. Peaks around 2pm and burns u up as sun setting. I didnt believe it until a friend brought equipment to prove it.

 

[Fusion is the future]

Find west chart then pls pass it on. The face South thing is pushed here but I still lean on side each is diff case.

My house position is this crazy west to east. Peaks around 2pm and burns u up as sun setting. I didnt believe it until a friend brought equipment to prove it.

My panels are angled 17 degrees NORTH must be 17 degrees SOUTH, but my panels are in the same time my carport and some panels more to compensate for the wrong angle is cheaper than building a new car port and it is in this way a lot more esthetic .
Still producing on a good day 16/18 KW not bad for 3,5 Kw installed after 8 years with a complete wrong solar angle , thinking to add a 2 strings , the equipment can handled it easy, and the construction i made have enough spare room for 2 more strings , the combiner box is already ready for 2 strings more.
Trying to get my power bill a bit down in the summer running 3, 2ton airco,s 2 double inverter type and 1 classic type .
My bill is now 75 bucks a month in the high summer,