DC module deviation from STC

Hi Karthik,

Yes, the GCR of 0.954 is for very closely spaced rows with just 11.5 cm of ground between rows. My diagram for GCR = 0.514 is for 1.75 m of ground between rows, or a distance between the bottom of rows of 3.385 m.

Best regards,
Paul.

Hi Paul,

Thanks for the information. Actually I am trying to learn different PV system simulation software, and I am trying to compare the simulation results for SAM, PVSyst and PV*SOL. 
And I got very close result(Annual Energy output) for PVSyst and PV*SOL for the same inputs.
But in SAM I am getting less energy output due to the Module loss.

So, I would like to know to how to solve the Module loss issue.

Thanks,
Karthik.

Hi Karthik,

Comparing results between SAM's Detailed PV model and other PV performance models requires ensuring that the input assumptions are the same for all of the models. This is described in the NREL comparisons I referenced above, which are available at sam.nrel.gov/photovoltaic/pv-validation .

The difference here may be in differences in the way SAM and the other models calculate self shading losses. You might want to try the comparison with GCR = 0.3, and for both the linear and non-linear self shading option.

Note that for the non-linear shading option, SAM models the reduction in beam irradiance as a DC loss that is applied to the array's DC electrical output rather than to the incident beam irradiance. This DC loss represents the response of a crystalline Silicon module with three bypass diodes to partial shading. The linear self shading model models self shading as a uniform reduction in the beam irradiance incident on the array. These approaches are described in Chapter 9 of the Photovoltaic Reference Manual (2018) available at sam.nrel.gov/photovoltaic/pv-sub-page-2 .

Thanks,
Paul.

Greetings, Paul.

I'm trying to validate the module deviation from STC loss to a project, but I'm not finding anything which explain how this loss is calculated.
I've read the #197 issue on github ( github.com/NREL/ssc/issues/197 ), trying to validate through this equation

Hi Gabriel,

The source code for the "Module deviation from STC" calculation is here:

github.com/NREL/ssc/blob/7b84c5b5eb73ab77bc72e081277c6c27a3a00f31/ssc/cmod_pvsamv1.cpp#L3042

The images in your post did not come through. If you want to use images in your post, please attach them as files and then insert them in  your post instead of copying and pasting them into the editor.

Best regards,
Paul.

Hello, I have similar problem, I get no electricity production at all and my module deviation from STC is 99.99%. I have made 3D shading scene, when I made simulation without 3D shading calculations I got OK results. Do you know what could be the problem? I am sending model in attachment.