Tilt angle of fixed tilt and tracker arrays

[laurahin]

Hi,

We were comparing results for single axis tracking systems and fixed tilt arrays matched by using N-S axis orientation.  We find that the production can differ at the same (nominal) angles.  We assume that the fixed tilt angle is well defined, so are wondering about the definition of PhiAng for SAT systems.  Is it the angle in the center of the hour?  average over the hour?  something else?  Thanks.

 

[Michele Oliosi]

Hi can you give some examples on the differences you find ?
Indeed you may be in a situation that has almost the same angles and therefore leads to slightly different results.

The PhiAng is the angle used for the whole time step, so in principle both results should match. Some other geometry factors may be at play: do you have exactly the same geometry of the tables ? (Module spacing, frames, etc) and are you using the same shading calculation ?

Finally, the diffuse shadings for trackers are done a bit differently, so comparing values after the shading loss may not lead to the same results, albeit the results should be close.