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System Advisor Model (SAM)

constraint fail in irradproc

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Jari
Topic Author

04 Oct 2018 13:41 #6465 by Jari

constraint fail in irradproc was created by Jari

Hi,

I try to run irradproc-module using irrad_mode = 2 when I receive the following error: "constraint fail: reason length_equal cannot find variable to test against, with 'length_equal=beam' for: diffuse"

Do I need to include beam irradiation data as an input when using irrad_mode=2? I only have global horizontal irradiation and diffuse available.

Furthermore, it is possible to run pvwatts without weather files as an input? I've using pvwattsv5_1ts but I rather do not like to run model in the loop - if possible? For me it would be perfect that I could read the data directly from memory and use that as an input for pvwatts.

I use SAMwrapper and python 3

thanks,
Jari

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pgilman

08 Oct 2018 21:22 #6466 by pgilman

Replied by pgilman on topic constraint fail in irradproc

Dear Jari,

When you set

irrad_mode = 2

in the irradproc module, you need to provide global horizontal irradiance (GHI) and diffuse horizontal irradiance (DHI) data. For that mode, you do not need to provide direct normal irradiance (DNI), also called beam irradiance.

The three modes are:

0: DNI and DHI

1: GHI and DNI

2: GHI and DHI

It looks like the irrad_proc module may be using the DNI (beam) data column to determine the number of records. You can try filling that column with values to see if that is the case.

You can use the pvwatsv5 module