Module parameters 'tamb' and 'pressure' are only Numbers in Module 'irradproc'

Hi Asif,

The 'irradproc' compute module contains functions for calculating the sun position and plane-of-array irradiance given data from a weather file. These functions are called by other compute modules that make up the SAM model (Detailed PV, PVWatts, Physical Trough Model, etc.).

The answer to your question has to do with the internal 'irradproc' objects. The module's source code is here:

github.com/NREL/ssc/blob/develop/ssc/cmod_irradproc.cpp

The ambient temperature and atmospheric pressure variables are inputs to the 'solarpos_spa()' function that calculates sun angles. It is called in the 'wfcheck' compute module once for each timestep in the weather file -- the code that calls that function reads the temperature and pressure data from the weather file.

The irradiance variables are inputs to the 'irrad()' function in 'irrad_proc' compute module. It reads in arrays of data from the weather file.

Best regards,
Paul.