Error message in stochastic mode

Dear all,

I am a new user of SAM. In particular, I would like to use this tool in stochastic mode in order to calculate the propagation of uncertainty from several input variables to the output of a photovoltaic system (array and system generated energy, performance ratio). Unfortunately, when I select the input variable, set the distribution and run the simulation, the following error message appears for each of the N samples (e.g. 100): “fail(irrad_mode, integer): number could not be interpreted as an integer”. In this case, the selected input variable is "PV radiation model", but for other variables it happens pretty much the same. I also tried to change location and weather file, but no way. I went through the SAM documentation and the tutorials, but so far I have not managed to find a solution to the problem. Maybe I am asking a silly question, and I am sorry for that, but what can be the problem? does the system really not accept non-integer values? Please find attached the original .sam file

Thank you very much for your kind help

Best Regards

Giorgio

Dear Giorgio,
The PV radiation model input is the one that determines how SAM calculates plane-of-array irradiance values from horizontal data in the weather file. It is at the bottom of the Location and Resource input page, under "Sky diffuse model." The only allowed values for that input are 0, 1, or 2.
I think you are trying to model a range of solar irradiance values. That is not possible to do using the stochastic simulations because SAM requires a weather file to represent the solar resource at the project location. The file contains thousands of values for solar irradiance, ambient temperature, etc. The stochastic simulation tool can assign a range of values to input variables that have a single value based on the distribution parameters you define. It cannot assign a range of values to input variables that are arrays of values.
You may want to investigate SAM's P50/P90 simulations for your analysis of solar resource data. Please see SAM's help system and these videos for more on that feature.
Best regards,

Paul.