Strings in 3D shading tool

Dear sir or madam,
I'm working with SAM for my bachelor thesis and I have a doubt regarding strings in the shading tool. In my array, I have 18 strings (according to the combination of panels/inverter chosen). However, after designing my system in the 3D tool, I am only allowed to assign the strings from 1 to 8. Is there anything I'm doing wrong? It should affect the % shading loss, so it is a big issue.
I would also like to ask, which tool is better for my case: My thesis consists of analyzing the effect of installed PV on energy consumption, and the available space includes both buildings and a terrain. I'm wworking with the 3D tool, which is sometimes quite slow when obtaining the time series and even crashes. Should I keep going with it?

Best regards and thank you in advance,

Mario Prinetti.

Dear Mario,

The limit of 8 strings applies if you use the partial shading model. If your array has more than 8 strings, I would recommend assigning a String number of 1 to all of your active surfaces. That will model the effect of shading by reducing the incident irradiance without making adjustments for partial shading of the array.

Best regards,
Paul.