Normal Beam too High

[Rafael Santos]

Hi Mermoud,

I imported a TMY from an hourly-based ascii file. The file contains only global horizontal irradiance and temperature values. When I checked the quality of the data, PVsyst said it seems to be ok, although it suggested me a time shift of 13 minutes (no logycal reason for that, since my data is hourly-based). My dataset has timestamps indicating the beggining of the dataset, the same way PVsyst works (I suppose), so I guess this is not the problem here.

Somehow I am getting very high values of Normal Beam Irradiance (close to 1400 W/m²) at the beginning of the days in some days of January, March, April, October and November. I attatched a print of January 24th, as an example. (GlobHor in yellow, DiffHor in red, BeamHor in black and BeamNor in blue).

I am pretty sure this is the reason why I am having big shading losses, as I am using tracker, and the beginning/end of the day has most losses.

Thanks for the attention, and regards,

Rafael

[André Mermoud]

This is typically a problem of time shift between the recording time of your data and the time of PVsyst (i.e. when the solar geometry is calculated).

Please see the help

In V 6.40: "Meteo Database > Notes on Meteo > Meteonote9_Time shift in meteo files"

In V <= 6.39: "Meteorological Data > Hourly Meteorological Data > Time shift"