ocrighton

Can someone answer this please.

Hello, I am have used the "Import ASCII meteo file" tool to import some meteo files that I downloaded from the NREL Data Viewer. I believe I have imported the files correctly, but for some the 'Check data quality' tab displays the message "The Clearness index of the best clear days seems high with respect to the clear day model. Check the values with the "Best clear day Ktcc" graph. I have attached images showing this message, and the "Best clear day Ktcc" graph. Again, I believe that these files were imported correctly, and that the data (GlobHor, Diffhor, etc.) in the PVsyst meteo file is correct. I am able to perform a simulation using the meteo file. I was wondering what the message I am seeing might mean. If the data in the meteo file seems like it is correct, and I am able to perform a simulation using the meteo file, should I disregard the message? Should I just consider that the data might be flawed, since it is resulting in unusually high clearness index values? Thanks very much.

I was wondering if anyone can provide any suggestions as to how one could model the effect of tree shading, taking into account the varying opacity of trees as their leaves fall off and regrow throughout the year? I understand that trees are treated as absolutely opaque in PVsyst, and there is no way of changing their opacity. Despite this fact, I was wondering if anyone could provide any alternative methods of performing this analysis. Thanks very much.