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Hello together, I want to analyze the deviation between measured pyranometer data and the simulation output data. The investigated project consists of vertical bifacial PV modules on a agricultural land. On the site there are three pyranometers measuring GHI, front irradiance and back irradiance. To compare the measured irradiance and the PVsyst data I am unsure which simulation variable to use. My current idea: A) Front irradiance = GlobInc + ReflFrt I use GlobInc instead of GlobEff, because the front-pyranometer is not affected the same of the optical losses (shadings, IAM, soiling) like the modules. Question 1: Is that assumption right? Question 2: Is ReflFrt already included into GlobInc? B) Rear irradiance = GlobBak + ReflBck Question 3: Is ReflBck already included into GlobBak? Please answer the three questions and give me general feedback on what to consider for the comparison between measured operating data and simulation output data. Many thanks in advance!

Hello PVsyst! I have a vertical bifacial East-West system, and I want to make sure that the irradiance received from the East-side should be the same whether I use east-front facing or west-front facing config. Same for West-side. Therefore, I made 2 simulations with the above 2 config, then compare just the Ressource losses (top part of the Loss Diagram). The results are attached as images. I don't think the horizon loss and soiling loss is integrated in the backside losses, hence I excluded these 2 losses from the front-side. The structure shading loss BackShd is also excluded for the back-side, in hope of a fair comparison. For the result, I expect the "Global Irradiance on front side (no soiling, no horizon shading)" of one configuration (East/West) to be more or less similar with the "Global Irradiance on rear side (no soiling, no structure shading)" of the other config (West/East). I highlight the 2 couples values in green and orange. West front-facing result: East front-facing result: Only the green pair seems to be similar (1.1% difference), the orange pair is 4.5% difference. This is already much better than some previous version of PVsyst, but I still want to know if my expectation is logical and if yes, what are the reason for this difference (the orange pair). Thank you!