why solar panel can use maximum 72 cell?

JAYMIN · July 2016

Hello dear friends

I have a question why solar panel can use maximum 72 cell in solar panel , we can not use more than 72 cell in solar panel ?

BB. · July 2016

A 72 cell panel has Vmp~36 volts (working voltage of panel).

There are panels with higher output voltage. And the higher the voltage, the smaller copper cable needed (savings in copper costs).

For grid tied systems with GT inverters that can have 200 to near 1,000 volts input voltage--Higher voltage panels can make sense for larger installations.

For Off Grid systems... With 48 volt battery banks and "typical" MPPT solar charge controllers with a maximum input of ~140-150 VDC maximum, it turns out there is a "difficult to use" Vmp rating for solar panels.

Roughly, you need a range of of Vmp-array from 72 VDC to ~100 VDC (standard test conditions/aka name plate rating). It turn sout that ~50 VDC to ~71 VDC Vmp rated panels are difficult to match to the system... Below ~71 volts is "too low" to charge a cold battery bank in hot weather (Vmp falls as solar panel temperature rises, and cold batteries need higher voltages to charge). And you cannot put two (or more) panels in series, because (again roughly), cold panel Voc (voltage open circuit) and exceed the ~140 volt maximum input voltage (Vmp/Voc rises as panel get very cold).

At this point there are not many panels with Vmp in the ~50-70 volt range for residential solar power systems (or higher voltages). For awhile, there were a fair number of "high voltage" thin film panels out there (mostly for Grid Tied system). And we did have a few posters that were in the "voltage bubble" with panels they had picked up on sale that would not work with their 48 volt battery systems and available MPPT solar charge controllers.

These days we do have a few "high voltage" MPPT solar charge controllers, and rumors of more high voltage MPPT solar charge controllers in the near future (next year or less?).

The only constant is "change"--And it is not a good idea to say something is "impossible"--There is always somebody out there that will prove you wrong.

-Bill

JAYMIN · July 2016

BB. said:

A 72 cell panel has Vmp~36 volts (working voltage of panel).

There are panels with higher output voltage. And the higher the voltage, the smaller copper cable needed (savings in copper costs).

For grid tied systems with GT inverters that can have 200 to near 1,000 volts input voltage--Higher voltage panels can make sense for larger installations.

For Off Grid systems... With 48 volt battery banks and "typical" MPPT solar charge controllers with a maximum input of ~140-150 VDC maximum, it turns out there is a "difficult to use" Vmp rating for solar panels.

Roughly, you need a range of of Vmp-array from 72 VDC to ~100 VDC (standard test conditions/aka name plate rating). It turn sout that ~50 VDC to ~71 VDC Vmp rated panels are difficult to match to the system... Below ~71 volts is "too low" to charge a cold battery bank in hot weather (Vmp falls as solar panel temperature rises, and cold batteries need higher voltages to charge). And you cannot put two (or more) panels in series, because (again roughly), cold panel Voc (voltage open circuit) and exceed the ~140 volt maximum input voltage (Vmp/Voc rises as panel get very cold).

At this point there are not many panels with Vmp in the ~50-70 volt range for residential solar power systems (or higher voltages). For awhile, there were a fair number of "high voltage" thin film panels out there (mostly for Grid Tied system). And we did have a few posters that were in the "voltage bubble" with panels they had picked up on sale that would not work with their 48 volt battery systems and available MPPT solar charge controllers.

These days we do have a few "high voltage" MPPT solar charge controllers, and rumors of more high voltage MPPT solar charge controllers in the near future (next year or less?).

The only constant is "change"--And it is not a good idea to say something is "impossible"--There is always somebody out there that will prove you wrong.

-Bill

THANKS DEAR but i searched in google but i did not find any panel which has more than 72 cells.

BB. · July 2016

Thin film panels like these (long out of production/business), see if link works (these panels were being discontinued in 2010 or even earlier):

http://www.secondsol.de/index.php?page=ad_showup&ID_AD_UPLOAD=5194

Are you looking for "high voltage" panels? More or less, there is a relationship between the size of the solar cell (raw silicon wafer) diameter and the size of the overall panel. Wafers have been made larger in diameter to reduce costs over the years.

Thin film panels have completely different construction and can be made in higher voltages without regard to physical raw material size.

First solar has some Vmp~178 volt panels:

http://www.firstsolar.com/-/media/Documents/Data-Sheets/Products/Module-Data-Sheet/Series-5-Datasheet.ashx

Don't know if you can purchase them retail.

-Bill

JAYMIN · July 2016

BB. said:

Thin film panels like these (long out of production/business), see if link works (these panels were being discontinued in 2010 or even earlier):

http://www.secondsol.de/index.php?page=ad_showup&ID_AD_UPLOAD=5194

Are you looking for "high voltage" panels? More or less, there is a relationship between the size of the solar cell (raw silicon wafer) diameter and the size of the overall panel. Wafers have been made larger in diameter to reduce costs over the years.

Thin film panels have completely different construction and can be made in higher voltages without regard to physical raw material size.

First solar has some Vmp~178 volt panels:

http://www.firstsolar.com/-/media/Documents/Data-Sheets/Products/Module-Data-Sheet/Series-5-Datasheet.ashx

Don't know if you can purchase them retail.

-Bill

Thank you sir for helping me actually we try to make panel of size of 2400mm * 1100 mm * 45 mm

littleharbor2 · July 2016

Image: https://us.v-cdn.net/6024911/uploads/editor/t3/t3ypgwh9ir3r.jpg

Here's

Image: https://us.v-cdn.net/6024911/uploads/editor/ho/yl9lzo9lywer.png

Here's a 196 and a 96 cell panel.
The 96 cell panel puts out 50.7 volts VMP and the 196 cell panel is a 12 volt panel.

Dave Angelini · July 2016

Hi Dear

Send us some cool SF breeze please!

littleharbor2 · July 2016

No such thing this time of year. The best we can hope for is low humidity....Dear lol

BB. · July 2016

Jaymin is probably from India.

Jaymin, you need to look at the application to figure out what will work.

For example my gt inverter needs around 3kWattt at 300 to 400 volts.

For me, 12 years ago, that was a string of 10 panels in series x 2 parallel strings (175 watt panels, 30 Vmp/60 cells).

If you have 450 watt panels at 100 Vmp, and 4kw rated gt inverter... Then 3-4 panels in series x 3 to 4 parallel strings.

It would not make sense to manufacture panels with no market. Or could not compete with others already in the market.

-Bill

Dave Angelini · July 2016

littleharbor2 said:

No such thing this time of year. The best we can hope for is low humidity....Dear lol

We get your monsoon sneaking up the east side of the Sierra and for about 2 weeks all the locals who use evaporation cooling are SOL.
Take care down there Dear....

JAYMIN · July 2016

BB. said:

Jaymin is probably from India.

Jaymin, you need to look at the application to figure out what will work.

For example my gt inverter needs around 3kWattt at 300 to 400 volts.

For me, 12 years ago, that was a string of 10 panels in series x 2 parallel strings (175 watt panels, 30 Vmp/60 cells).

If you have 450 watt panels at 100 Vmp, and 4kw rated gt inverter... Then 3-4 panels in series x 3 to 4 parallel strings.

It would not make sense to manufacture panels with no market. Or could not compete with others already in the market.

-Bill

yes dear i am from india and our company wants to install and make BIPV and size of panel can be 2400mm * 1100 mm * 45 mm so howmany power can produce by this size?

BB. · July 2016

Jaymin,

The size and power ratings of your panels will depend on the source of your raw products (for example, the diameter of cells you can purchase) and whether you choose to use "round" or square cells (ingots/cells are "cut square"--Wasting material but increasing active cell density for your panel). Mono vs Poly silicon cells, how you will wire them, by-pass diodes, etc. Or will you be using thin film panels (have their own issues).

This is stuff that your design/manufacturing engineers will have to pencil out for you (price of panels vs performance vs market acceptance) will have to give to your sales/management teams.

I can estimate output power (y square meters of your panel vs a sample panel of x square meters) for a generic panel. But, at some point, the details matter--And I do not have the information or knowledge to really help with that level of detail.

-Bill

bill von novak · July 2016

JAYMIN said:

Hello dear friends

I have a question why solar panel can use maximum 72 cell in solar panel , we can not use more than 72 cell in solar panel ?

There's no max. I have used 84 and 96 panel cells. It all comes down to what a reasonable voltage is, and how many cells you can fit in a given form factor.

Belmont Solar · July 2016

Much larger than 40" X 77" and the solar modules tend to get too bulky to handle very well. Plus anything much bigger would cost more to ship, due to requiring unusually large pallets. They would also require significantly thicker aluminum frames in order to keep them strong enough

why solar panel can use maximum 72 cell?

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