[TRNSYS-users] Trough + tracking mode

[PORRAS PERALES, MARCOS]

Dear all,
I am have a question about what tracking mode I have to use when using 
Trough collector, because the results of tracking mode 1(fixed surface) 
and Tracking mode 3(Single-axis tracking, axis is in the plane of the 
surface) are the same.
However, when I use Tracking mode 2( Single axis tracking, vertical 
axis (fixed slope, variable azimuth) are completely diferent and better 
than the others.

Does someone know the reason??
Do I have to use Tracking mode 2 instead Tracking mode 3?

Thanks in advance,

Marcos Porras