Exact number of modules

[Sascha N.]

Hello, 

I would like to ask how I can set or modify the exact number of modules in my PV system. 

In an east/west array I would like to simulate a PV system that is partly already installed- so the number of modules is known and has to match. 

However, when I try to define it through the available settings in the system definition (namely: number of inverters/MPPT inputs, modules per string and number of strings) I never get closer than 1 module of difference to my desired number of modules. 

I even get quite often an odd number of modules- which is infeasible for tent-shaped east-west-orientation (/\). 

I also tried the pre-dimensioning tool- it always suggests different configurations.

I would appreciate your help very much.

Best regards

[Linda Thoren]

Dear Sascha N. 

By creating subarrays you can define different amount of panels per string, different amount of strings per MPPT, orientation etc. This gives you a large liberty to define exactly the amount of modules required. You find the list of subarrays to the right in the system window.

I hope this helps, if you wish for more precise assistance, please provide us with more information of your system.

Kind regards

[Sascha N.]

Hello Linda, 

Thank you for your help.

In order to demonstrate the problem, I wll give you rough numbers of a sub-field I struggled to simulate: 

-2868 modules

-430Wp modules

- 9 inverters

- 125 kW inverters

The closest number to the desired amount of modules I could achieve with the available settings (you described above) was 16*179= 2864. This difference of 4 modules is unacceptable for our client. In reality, not all strings are of different sizes. Varying numbers of strings are connected to each inverter input (e.g. 1 or 2 strings per MPPT-input). 

Please let me know if we can simulate real systems with these characteristics with PVsyst - maybe you can suggest a setting in order to achieve the desired number of modules. 

PS: I would like to avoid confidential data in this public forum- if you need the modul and inverter models and the total system size, I would be happy to send them to you privately.

Best regards, 

Sascha

[Linda Thoren]

Hello Sascha,

By using the mixed orientation option, all the strings are the same lengths and by increasing the numbers of strings, you then increase with 16 panels every time. You have more liberty if you define sub-arrays, you then assign each sub-array to an orientation/inverter/MPPT. 

In the Sub-array name and Orientation dialog you can define a name of your sub-array and the orientation, in the generic example below I have 2 orientations, 3 subarrays in the first orientation and 1 subarray in the second orientation, see the list of subarrays to the right. You can create a new subarray, or copy a subarray by using the first two icons under the list of subarrays.

I also activate the use multi-MPPT feature for this example and I activate the power sharing. Using these features I have defines a global system with 2868 modules and 9 inverters (1588 panels and 5 inverter in orientation 1 and 1280 panels and 4 inverter in orientation 2).

I hope this example helps you to define your system. If not please send your project to support@pvsyst.com

Kind regards