POA from reference cell input reading correctly but not producing DC results

Hi team,

I am running a weatherfile with 'POA' as input, selecting 'POA from refernece cell' on the irradiance mode, and the results show correct Plane of Array irradiance but no values on the performance (DC power, etc..). Any suggestions appreciated

Notes on the issue:

-SAM 2022.11.21

-Weaterfile attached, field data from NREL. I know it works because the POA values can be seen in the results, adn because I get the notice that I am using a POA for simulation when running:
 

-Tested on pysam, same issue (that's where I first encountered it)

-Tested the rest of the simulation with a similar field data weather file but with DNI and DHI provided and selected as the irradiance mode ('irrad_mod'), and that one did run, so it is something to do with the irrad_mod = 3 ('POA with reference cell') option

-Results showing performance values on 0:
 

 

Hi Silvana,

This issue is caused by using POA irradiance data with self shading enabled. I'm not sure the POA option is designed to work with the self-shading model enabled.

The model should run with self shading disabled on the Shading and Layout page (subarray1_shade_mode = 0 in SSC / PySAM).

Is your intention to use POA data with SAM's self shading model?

Best regards,
Paul.

Many thanks Paul, that did the trick. Sorry I didn't caught that on the pysam documentation.

S.

On a semi-related note.

Using NSRDB data through Eagle, the data out of the h5 file is in Dataframe format not csv. I am assigning it directly and bypassing the csv file this way:


pv2.SolarResource.replace('solar_resource_file') # Removes the file so it doesnt try to read it.
pv2.SolarResource.assign({'solar_resource_data':{'dn':list(df_weather_gid.dni),
'df':list(df_weather_gid.dhi),
'tdry':list(df_weather_gid.air_temperature),
'wspd':list(df_weather_gid.wind_speed),
'lat':meta_dict,
'lon':meta_dict,
'tz':meta_dict,
'Elevation':meta_dict,
'Year':list(df_weather_gid.index.year),
'Month':list(df_weather_gid.index.month),
'Day':list(df_weather_gid.index.day),
'Hour':list(df_weather_gid.index.hour),
'Minute':list(df_weather_gid.index.minute),
'alb':list(df_weather_gid.surface_albedo)}})

Despite having use_wf_albedo set to true, I still have to set a monthly albedo values for it to run.
pv2.SolarResource.albedo = [0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2,0.2]

One it runs, the results weather data looks good (dni, dh, albedo), the POA front ('poa_front') looks mostly okay but some really high peaks at some opints... but mostly again I have no values on the cell temperature or power... does this mean I also have to override the shading or am I missing a different variable/change when setting this up?

Hi Silvana,

It looks like the 'albedo' input is required if 'use_spatial_albedos' is set to zero, regardless of 'use_wf_albedo'. This is a bug that we will fix. The workaround you found is to set 'albedo' to a valid value (array of 12 values between 0 and 1). If 'use_wf_albedo = 1', SAM should ignore the monthly values.

Please do verify that 'subarray1_shade_mode = 0' (for all enabled subarrays 1-4) when 'irrad_mode = 3' or 'irrad_mode = 4' (use POA reference cell or pyranometer data from weather file).

Best regards,
Paul.