Using solar irradiation data provided straight from a pyranometer as measured

Hi, I have been given sunlight irradiation data measured from a pyranometer and provided on an "as-is" basis.  This would have been measured under a number of weather conditions.  I like to use the pyranometer measurements in place of standardised weather files on SAM.  Should I treat it as the equivalent of GNI, GHI, or something else?

Since the pyranometer  measured the sunlight conditions continuously over an one-year period under a variety of conditions, I suspect the sun irradiation values provided wouldn't exactly be the same as any of the standard measurement defined.  If you could advise whether I should seek clarification from the provider, or I could treat it under GHI, GNI, or even DHI or DNI, or something else entirely that will be great.

(In addition, the format of the output file is different from the standard weather file that SAM accepts, but the format issue is relatively minor and I think I know how to get around this.  It is the what the irradiation values represent that is posing the biggest issues for me)

Thanks.

 

Hi Joel,

You can include any combination of GHI, DNI, DHI, and POA irradiance data in your weather file in the SAM CSV format. See the format description in the "SAM CSV Format for Solar" topic of SAM's Help system: samrepo.nrelcloud.org/help/weather_format_sam_csv_solar.htm

If your weather file includes POA data, to use it as input for the Detailed PV model, in a simulation, choose the appropriate "POA" option under Albedo - Sky Diffuse Model - Irradiance Data (Advanced) on the Location and Resource page.

 

If you use POA irradiance data as input, SAM only uses the POA irradiance data from the weather file. It uses a decomposition model to calculate the DHI and DNI values from the POA data. That is described more in the "Location and Resource" Help topic in the section for the advanced inputs: samrepo.nrelcloud.org/help/pv_location_and_resource.htm

Best regards,
Paul.