constraint fail in irradproc

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

Dear Jari,

When you set 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 input to provide a table of weather data instead of reading a weather file. The table keys are , , , , , , .

Note that the PVWatts module requires DNI and DHI as input. If you only have GHI and DHI, then you can use the irrad_proc module with to calculate the DNI from those components as the output variable .

Best regards,
Paul.