MNE

Dear Mr. Mermoud, on Fri Aug 17, 2012 4:58 you posted at "Simulations : results" following: Now if you start from Meteo data in monthly values, the synthetic hourly data file is constructed using a stochastic process: with 2 different executions you will have completely different years (sequences of days and or hours in a day). This may lead usually to discrepancies of the order 0.5 to 1% in the yearly result. These are indeed unavoidable uncertainties due to the stochastic models used. Therefore if you want to perform a quite identical simulations as a colleague, you have to share the exact hourly meteo file used (*.MET). Former i have used the programm WetSyn for creating hourly meteofiles. By using the program WetSyn it was possible to fix the stochastic factor. When different users have used the same factor the same values have been calculated. Could it be possible to do the same in PVsyst. Maybe two different versions. One like now by using a random variable and another version by choosing the variable to fix it?

Dear Mr. Mermoud, we actually measure global irradiation and diffuse irradiation in module plane. When i do use the ascii import for global irradiation in module plane, PVsyst converts to horrizontal data and back in to module plane. Comparing the PVsyst Output file variable DiffSInc with the measured diffuse irradiation in module plane the values deviate in my specific calculation on a daily basis from -17,2% to +72,4%. These deviations occure on days with low irradiation as well as on days with high irradiation. For a specific performance calculation these deviations end up in an uncertainty of results. Would it be possible to fasten the implementation anyhow?

Dear Forum User, i have actually measured diffuse and global irradiation in module plane and would like to use exactly these values for calculation. Could you please implement the possibility of this import. Greetings Martin