What does the "Nb. of trackers" in the "Unlimited trackers, horiz. axis" Orientation option do?

[AxelOlson]

Could someone please explain how the "Nb. of trackers" number affects the output. I know that it does as I have seen it range from 0% near shading losses to 2.2% near shading losses when I have varied it from 1 tracker to 200 trackers. Interestingly, I created a detailed layout in a shading model that gave me 1.8% near shading losses. To get this value in the unlimited trackers model I would need to set this number to 5...which seems misleadingly low. Any information is appreciated as I am not seeing a good explanation on the PVsyst help documentation as to what changing the "Nb. of trackers" field practically does.

[dtarin]

100 is a good default number. For a very large site, selecting higher is fine too, but it comes down to your system size. Shading losses most of the time are higher in the unlimited sheds model compared to a 3D scene (I have never seen it less but maybe in some cases it could be), so that is not unusual. 

Nb trackers is the number of rows. The unlimited sheds method excludes edge effects for the most part and assumes the rows are infinitely long. 

[Michele Oliosi]

@dtarin is quite correct. The shadings in the unlimited sheds are idealized so the value won't necessarily match exactly the detailed calculation. The linear shadings are slightly overestimated. The shading-induced electrical mismatch losses are either overestimated or underestimated, depending on how many partitions ("modules in width") are chosen.

Please look at the help (Project design > Shadings >Electrical shading loss according  to module strings) for more information on this choice.

When you diminish the number of rows, the importance of the first row increases proportionally. The first row isn't shaded, meaning that the shading decreases.