POA data in weather file

Hi Gabriel,

The POA irradiance data option is only available for the Detailed PV model. It is not available for PVWatts.

To enable the option, be sure to choose one of the POA options from the list under Albedo - Sky Diffuse Model - Irradiance Data (Advanced) on the Location and Resource page:



Make sure the column of  POA data in your weather file uses one of the following headers as described in the SAM CSV for Solar Help topic :

If all of those conditions are met, please attach a copy of your weather file so I can help troubleshoot, or This email address is being protected from spambots. You need JavaScript enabled to view it..

Thks for the quick reply.

I forgot to say but I'm using Detailed PV model No Financial model. My bad.

My header is "poa" to the poa data.

I read this problem on github ( github.com/NREL/SAM/issues/610 ), but I was unable to solve it by my own.

The file "phoenix_az_fake_poa" is from github and it worked on my simulation, but my file "FVT.-5.249.-37.974.RMY.00M_SAM_1hr" is not working.

I didn't get how I have to change my file to it gets alike with github file.

Hi Gabriel,

The albedo data in your file is incorrect. The albedo values should be between 0 and 1 as described under "Albedo - Sky Diffuse Model - Irradiance Data (Advanced)" in the Help topic for the Location and Resource page: samrepo.nrelcloud.org/help/pv_location_and_resource.htm .

The loss diagram represents losses over the entire year, so I would expect it to be distorted by your special weather file that repeats 10 days of data to create a full year. The calculations used to generate the loss diagram are different from the simulation calculations, so the time series results should be reasonable even if the loss diagram is not.

We are investigating further and will let you know if we discover more.

Best regards,
Paul.

Thks Paul for the information.

I fixed my albedo values but still the result is a generation of negative energy. Even with a file without albedo (file below). But the problem is when I check the check box "POA from pyranometer", this option is always leading me to this scenario of negative energy generation. Do you thing that's also because the weather file is repeating the data?

About the loss diagram, it's a bug generated by weather file data. So I can't make a loss analysis when I have a weather file which repeats the same data all over the year?

With that I wonder if there is other option to avoid this bug and still simulate a sub-annual data simulation. I would like to let LK programing or PySam as my last resource hahah

Thks again, Paul. You've been very useful.

Best regards

Hi Gabriel,

We are looking into why the pyranometer and reference cell options are working differently with your weather file. For now, perhaps you could use the reference cell option.

The loss diagram reports losses over one year, so I am not sure what the information on the diagram would mean when your weather data is not for a complete year. You might find more useful results on the Time Series or Data Tables graph if you focus on the period of interest to your analysis and ignore the data for the other times.

I will let you know when we have more information about how to handle this special case.

Best regards,
Paul.

Very very thank you, Paul.

I'll wait then.

Best regards.