2-axis tracker with one fixed axis vs 1-axis trackers

[Emkey]

Hello,

I know the tiltle sound pretty strange, but I'll try to explain myself in the best way possible.

We received a simulation from one of our clients which used a configuration (I will call this configuration A) which is as follows:

1. Tracking two-axis, frame E-W: Frame min tilt=0°,Frame max tilt=0°, Axis perp Azimuth=0°

 

We developed an identical configuration with a 1-axis tracker (I will call this configuration B):

• Tracking Plane, tilted axis: Axis tilt=0°, Axis Azimuth=0°

 

Basically, configuration B usess a 2-axis tracker as a 1-axis tracker. Now, except for the difference in the computational time (much longer with configuration A), we unexpectedly found a great difference in the annual production (much higher in configuration A), which is given by a "near shading loss" of -2.5%, which concerns only the configuration B.

Could you help me understanding why do we have a different loss when all the other parameters are the same?

I attached a copy of the tracker used in the configuration A, if this helps understanding what I explained above.

Thank you very much,

Marco