Interpreting Shading Loss in 8760s for PV Capacity Testing

[Jherche]

Hello,

 

I am running a PV capacity test per ASTM2848-13 and it is important to filter out any data where shading is present. I am struggling to interpret the shading losses per the 8760 outputs. 

 

I have FShdBm and ShdBlss. Is there shading whenever FShdBm is < 1 and whenever ShdBlss > 0? Should I use any other 8760 outputs or is this sufficient?

 

Thanks.

[Linda Thoren]

Hello,

Indeed filtering out these two variables should be sufficient to remain compliant with the ASTM 2848-13 standard

[Jherche]

@Linda Thoren Just so I'm clear, can you elaborate on the significance of both terms? What do the values for FShdBm and ShdBlss mean?

For capacity testing should the values of ShdBlss be zero? What happens when you get values > 1? is that just a simulation error? it makes sense to me that 1 would correlate to 100% shading.

FShdBm = 1 means no shading?

[Linda Thoren]

Yes

• FShdBm = beam shading factor. FShdBm < 1 indicates that beam (direct) irradiance is being reduced by shading. 
  • 1.0 = no beam shading
  • 0.95 = 5% beam shading loss
  • 0.00 = fully shaded from beam irradiance
• ShdBlss = beam shading loss value. ShdBlss > 0 indicates a non-zero beam shading loss, so this also means shading is occurring.
  • 0 = no shading loss