Hello,
I think I would recommend using the data from the pyranometer for the subarray that has the same tilt and azimuth angle as the pyranometer. For the POA irradiance options (Under "Albedo - Sky Diffuse Model - Irradiance Data (Advanced)" on the Location and Resource page), SAM assumes that the POA data is measured in the same plane as the array.
SAM does not include an option to "correct" POA data for different array orientations. You could manipulate the POA data outside of SAM and use it as input. The weathe file format for SAM's solar models is descrbed in the "SAM CSV Format for Solar" topic in help here, which you can find by clicking Help in SAM or online here:
samrepo.nrelcloud.org/help/weather_format_sam_csv_solar.html
Also, if you are comparing measured time series data from the system, you may want to consider using weather data for the year that corresponds with the measured data. For example, if the POA data was measured in 2022, then you would want to use a weather file from 2022 rather than a TMY (typical meteorological year) file.
Best regards,
Paul.
