About sub-array

[Minh Hào]

Hi there, 
I am using PVsyst for some rooftop solar project designs. And here are my problems:

1/ Sharing power function. "The power sharing of the PVsyst model acts between sub-arrays, but not within a sub-array." I didn't understand it clearly. Could anyone explain it more? Thanks
2/ I have an old project. It used Sungrow SG125cx-p2 with a DC single-line diagram like the one below. My question is: How can I define this in the sub-array function? Because the old simulation looks incorrect.
More info: DC/AC = 1.337. PV 580Wp. And I have 11 Inverters configured like this. 

[Linda Thoren]

Hello,

1/ It is important that you have a multiple between the number of strings and number of MPPT inputs so that PVsyst can equally distribute the strings over the MPPTs, since there is no power sharing within the sub-array, only between the sub-arrays. 

 2/ I understand that your inverter has 12 MPPTs, some MPPTs with 2 strings and others with 1 strings, some with 18 panels in series and others with 19. You can either define each MPPT individually in separate sub-arrays:
- 1st sub-array with 2 strings of 18 panels
- 2nd the same
- 3rd sub-array 1 string of 18
- etc.

Or you can group all the MPPTs with the same configuration in the same sub-array, for instance:
- 1st sub-array with 3 MPPTs with 6 strings of 18
- 2nd sub-array with 3 MPPTs and 3 strings of 18 (just to highlight here that it would not be correct to define 6 MPPTs with 9 strings of 18, since it would not be a multiple between the number of MPPTs and number of strings)
- 3rd sub-array with 5 MPPTs with 5 strings of  19
- 4th sub-array with 1 MPPT with 2 strings of 19

If you have 11 inverters with the same configuration, you can multiply the number of MPPTs and the numbers of strings in each sub-array with 11 (33 MPPTs and 66 strings in the first sub-array etc.)

I hope this clarifies the use of the Power sharing feature. You find more examples in the following youtube tutorial:

 

[Minh Hào]

43 minutes ago, Linda Thoren said:

Hello,

1/ It is important that you have a multiple between the number of strings and number of MPPT inputs so that PVsyst can equally distribute the strings over the MPPTs, since there is no power sharing within the sub-array, only between the sub-arrays. 

 2/ I understand that your inverter has 12 MPPTs, some MPPTs with 2 strings and others with 1 strings, some with 18 panels in series and others with 19. You can either define each MPPT individually in separate sub-arrays:
- 1st sub-array with 2 strings of 18 panels
- 2nd the same
- 3rd sub-array 1 string of 18
- etc.

Or you can group all the MPPTs with the same configuration in the same sub-array, for instance:
- 1st sub-array with 3 MPPTs with 6 strings of 18
- 2nd sub-array with 3 MPPTs and 3 strings of 18 (just to highlight here that it would not be correct to define 6 MPPTs with 9 strings of 18, since it would not be a multiple between the number of MPPTs and number of strings)
- 3rd sub-array with 5 MPPTs with 5 strings of  19
- 4th sub-array with 1 MPPT with 2 strings of 19

If you have 11 inverters with the same configuration, you can multiply the number of MPPTs and the numbers of strings in each sub-array with 11 (33 MPPTs and 66 strings in the first sub-array etc.)

I hope this clarifies the use of the Power sharing feature. You find more examples in the following youtube tutorial:

 

Hi, 
Your answer helps me a lot. But there is one thing I'm concerned about. Do I need to check on the "Multi-MPPT feature"? Because the message describes my inverter configuration exactly, it also lowers my production simulation. I wonder which is correct.

 

[Linda Thoren]

Hi,

Indeed you should check the multi-MPPT feature and click on the Power sharing button to activate the power sharing feature (drag the sub-array from the list to the right to the configuration to the left). By defining this correctly, it would be expected to decrease the overload loss over nominal inverter power.