Inconsistency Regarding Sun's height

[Guest]

Dear all,

the solar elevation angles for a given location differ when obtained from the simulation output and from the Tools/Graphs and Tables of Solar Parameters menu. More specifically, the elevation angle in the first hour of sunshine in the morning and the last hour in the evening differ, while all other values are the same.

When calculating the elevation angle myself according to the PVsyst help, I get the same values as in Tools/Graphs and Tables of Solar Parameters. Why do the two outputs differ? How is the Solar elevation in the morning and evening calculated in the simulation?

Thank you very much in advance.

Edit: Note that 0.5 was added to the Time zone section in the Graphs and Tables... Menu in order to get the Solar Elevation angles in the middle of the time interval, as done in the simulation.

[André Mermoud]

The first and last hours of the day are partial hours (e.g. morming: between sunrise and the full hour).

In these cases PVsyst calculates the solar geometry in the middle of the interval (sunrise hour - full hour), not in the middle of the hour.