Error "Info: parameter Pitch was set, Warning: parameter Pitch did not change, The GCR used for the backtracking algorithm (0.675) differs from ..."

[Sunny Day]

I am attempting to run batch simulations where the pitch is varied (screenshots are attached).

The tracker pitch in the shading scene is 3m. The following error is being displayed for runs where the simulated pitch differs from 3m:

"Info: parameter Pitch was set, Warning: parameter Pitch did not change, The GCR used for the backtracking algorithm (0.675) differs from the average GCR (0.289)."

The following error is being displayed for runs where the simulated pitch is 3m:

"Warning: parameter Pitch did not change"

I ran some tests in batch mode and in single simulation mode and a quick comparison indicated the results were the same i.e. the error messages returned when running in batch mode are bogus. Is anyone able to confirm that the error messages are bogus?

[Michele Oliosi]

You still have the column "Pitch" in your batch file. Since there are only trackers in the scene, the pitch cannot be changed, which triggers the warning. What matters is the other column, "Trackers pitch EW". I would recommend removing the "Pitch column" and rerunning the batch.

Note also that you should be mindful of how the backtracking parameters were set (3D scene > Tools > Backtracking management):


Here the mode is manual (automatic unchecked). This means that if the batch mode changes the pitch, the backtracking algorithm will not follow, and the yield may decrease (either from being suboptimally oriented or from shadings).

Instead if you choose "Automatic", then the backtracking will adapt to the changes from the batch.

 

 

[Sunny Day]

Hi Michelle. Thank you for the response. Removing the Pitch column did remove the first error ("Warning: parameter Pitch did not change") but the second error ("The GCR used for the backtracking algorithm (0.675) differs from the average GCR (0.289)") remains. Below I will provide a minimum reproducible example to illustrate the error.

• 1. Open _DEMO_COMMERCIAL.PRJ
  2. Click on Orientation and change to 'Tracking, horizontal axis N-S' and enable Backtracking. Click OK.
  3. 
• 3. Click on Near Shadings, then on Construction/Perspective. Then Create/Array of Trackers
  4. 
  4. Default array of four trackers appears. Make no changes. Close Object.
  5. Click on Tools/Backtracking management. Verify that "Automatic" is checked
  6. 
  6. Compute shading factor table.
  7. Click OK to exit Near Shadings.
  8. Click on Advanced Simulation, then Batch simulation.
  9. Select to vary only "Pitch E-W between trackers"
  10. 
  10. Under the "Batch CSV Files" tab, select "New file" and then click OK to close the window.
  11. Open the BatchParams file, which looks like this:
  12. 
  12. Modify it to schedule a batch simulation for three scenarios with varying tracker pitch:
  13. 
  13. Click "Simulation" to run
  14. 
  14. Inspecting the results, we see the error message is returned for  cases where the tracker pitch varies from the tracker pitch in the 3D drawing in Near Shadings
  15. 

 

It seems the tracker pitch is changing each simulation but the GCR used for backtracking is not.

 

Do you know what I'm missing?

[Michele Oliosi]

I have checked further, and the pitch seems to be effectively changed, even for the backtracking algorithm. This is despite the message saying otherwise. The message seems to stem from a check, before updating the backtracking algorithm. It is therefore not relevant.

Note that this does not happen in version 8 anymore, in principle. Have you checked ?

[Sunny Day]

Correct, I do not see these error messages with v8.0.1 (all of the above was done with v7.4.8). Thank you for your help, Michele!