ckremin

Dear PVsyst development team, I want to suggest to implement a digital authentication feature of the used model files which verify source and authenticity. At the moment PVsyst model files are easily modified by any user and those modifications are hard to detect. In order to check the validity of the PAN/OND file, a carefull comparison between a provided measurement report and the data of the model file has to be performed. The suggestion is that module manufacturers and accredited testing labs are provided with authentication codes with which they can sign their generated PAN/OND files. The status of the model file will also be shown on the PVsyst report with a label. Any alteration of the model file will void that authentication and the label will not be shown. This will greatly enhance the trust in the underlying data which currently is a huge factor of uncertainty. I hope this suggestion finds you well. Kind regards, Christoph Kremin Director Systems Engineering, CERO Generation

Yes, the used modules are bi-facial types. You are welcome and glad to help.

Dear PVsyst Team, I have just installed the new update 7.2.0 and loaded a project with single axis trackers (backtracking enabled) which I simulated with 7.1.8 yesterday. The new results with 7.2.0 show a huge negative delta to 7.1.8! I deactivated backtracking in the shading scene and did another run. The differences in yield were marginally. Backtracking had close to no effect when it should. Finally I redid the whole shading scene as I hoped that having made the shading scene in 7.1.8 may cause the issue. To my great surprise the new results with the remodelled shading scenes were even worse and now backtracking was even lower than without. The shading factor table showed an impact even with backtracking enabled, which was never the case before. Please find the results below. I am sure there must be an error in the calculation and setup. This cannot be correct. Kind regards, Dr Christoph Kremin Director Systems Engineering CERO Generation

Dear PVsyst Team, I made a brief comparison study between PVsyst 6.8.7 and 7.0.0 with identical project settings (identical copies of the variants) to see the difference in the simulation. The new version provides slightly reduced results for bifacial c-Si. Especially the treatment of backside irradiation but also the low irradiance loss have seen some significant changes which affect future simulations. I used various c-Si bi-facial and thin-film modules on Fixed2P and SAT1P mounting systems for a site in the US. I noticed a significant performance reduction of up to -1.5% for the c-Si modules. Especially modules who showed an extremely good low irradiance behavior before were severely impacted. Much to my surprise there was no significant change in the result for thin-film modules! I have attached the results overview to this post. Can someone from PVsyst please comment if this is indeed correct and intended or if this is a potential error in the new simulation? That would be highly appreciated. Until further clarification of these differences, I recommended to my team to stick with the previous version 6.8.7. Thank you and kind regards, Christoph Kremin Director, Systems Engineering + R&D | Blueleaf Energy Results overview v6.8.7 vs v7.0.0

Dear André, dear PVsyst development team, would it be possible to get an indication on the timing, when you are planning to release further updates regarding bifacial modelling? Are there any plans to revise the bifacial modelling methodology? We are currently looking at a significant number of large scale PV opportunities, but are struggling to acurately simulate the bifacial yield gain with PVsyst. Measurements indicate that the numbers are very conservative, when it comes to model the bifacial energy gain. Kind regards, C. Kremin

I understand that the required Gamma must sometimes be reduced to values below 1 to better fit the results from todays indoor measurements. But this also means going out of the physically meaningful range below 1. As i now understand it, there are two possibilities to this problem: 1. The weaklight measurements are flawed and give false results. 2. The model (or better its limitiations) is not correct any more and needs to be adjusted. The attention seems to be with point 1 at the moment, but isn't applying the one-diode model to a complete PV module a simplifcation which would justify dropping the Gamma limitations?