Bug: Self Shading and "NaN' for Energy Generated

Hello Paul,

I think I found a bug in the self shading calculator. It tends to create "NaN" as the annual energy generation in random years. It is especially buggy if you create 2 subarrays, and then only calculate self shading for one of them. This is compounded by GCR ratios between the two subarrays that don't match, like 0.55 for subarray 1 and 0.9 for subarray 2.

Sometimes the simulation runs just fine, but then when I was running a parametric analysis and changing the tilts of the panels and the costs of installing the, the system would crash.

See the attached file and crash report.

Regards,
David

Dear David,

I could not replicate either of the issues you describe. I am also not sure I understand what you mean by "create 'NaN' as the annual energy generation in random year." Do you mean the annual energy value reported on the Cash Flow tab?

We will try to investigate further, but if you could provide any additional information, that would be helpful.

Best regards,
Paul.

Paul,

I have uploaded another set of crash reports and a new SAM file. I enabled linear self shading, set the row width to 150, and then ran the simulation, and SAM crashed again.

When I referenced "NaN", I was referring to the energy generation per year in the Cash Flow tab, as you stated ablove.

Regards,
David

Dear David,

Thank you for the additional information. I ran a simulation in the latest file you attached, and it did not generate the "NaN" values you describe.

From the information in the crash report, it appears that you may not be using the latest version of SAM. You can find the version number by clicking Help, and then when the Help window opens About. The latest version is SAM 2016.3.14 Revision 4. If you are using an earlier version, please download and install the latest version.

If you continue to have trouble with the latest version, please try a different weather file (perhaps choose one of the "TMY2" files from the list on the location and resource page and change the subarray azimuth angle accordingly), and see if the problem persists.

Best regards,
Paul.

Thanks Paul,
I will download the latest version. Could you guys push release notifications in the "Announcements" section whenever you start SAM? I always seem to be using an older version of SAM...

I will let you know if the problem persists.

Regards,
David

Hi David,

Thank you for that suggestion. For now, we can only push update notifications for revision updates to a given version number, but not when we change version numbers. We will see if we can make improvements to how this works for the January 2017 release.

Best regards,
Paul.