Fixed area: How to simulate tilt/pitch variations and adjust module count accordingly?

[Neill]

Hi,

For a schoolproject i am investigating different ways to integrate PV on standardized containers. Now, with a batch simulation i want to evaluate the pitch and tilt in order to find the maximum yearly energy. It's not entirely clear to me what happens to the number of modules when the pitch changes. With a fixed available area, increasing the pitch should reduce the number of modules that can fit, and therefore also decrease the total energy production. If I understand correctly, PVsyst doesn't take this into account automatically, and you have to manually calculate how many panels fit within the area for each pitch value. Do I understand this correctly? And if so, could you explain the easiest way to do this?

Thanks!

[Bruno Wittmer]

Your understanding is correct. The batch mode of PVsyst will indeed not change the number of modules, strings or inverters when you change the pitch. You need to specify those parameters explicitly for each simulation in the batch run and ensure beforehand that they are consistent.

In your scenario, where you have standardized containers that will take the PV modules, it should not be too hard to calculate the number of strings that work for a given pitch, and possibly adapt the number of inverters or MPPT inputs. This will give you a limited number of scenarios, for which you then need to vary the tilt. 

The simplest approach for your case would be to create the batch parameter file with PVsyst, where you choose as parameters tilt, pitch, number of strings and number of inverters (or MPPT inputs). Import this file into a spreadsheet software like Excel or LibreOffice, and fill in lines for all combinations of pitch and tilt. For the number of strings use a formula that computes the number you can fit on the containers as function of the pitch. For the number of inverters use a formula based on the number of strings. If you save this again in CSV format, you can proceed to run the batch simulations.

If you are unsure about what PVsyst will do exactly in a given batch simulation, you can use the option 'Calculation version for specified runs', when you first define the batch parameters. This will create an additional column in the batch parameter file, where you can fill a 'Y' for runs you would like to cross-check. These runs will then create variants in your project, that you can open and examine once the batch run is finished. To easily spot these new variants in the project, PVsyst will use the 'Comment' column to generate the titles of the variants.