In a project, why the values of the Site and the Meteo file don't match ?

[André Mermoud]

In PVsyst, the meteo data may be specified in 2 kinds:

- SIT files, which define the location of a site (Site name, Country, Latitude, Longitude, Altitude, Time zone).

In addition the Site includes meteo values (at least Global horizontal irradiation and temperature) in monthly values.

- MET files, which define meteo data in hourly values.

NB: The MET file includes an internal SIT object for the determination of the location.

Now within a project, you begin by choosing a location, i.e. a site in the database.

Then you choose a MET file for the hourly meteo data which will be used in the simulation.

You can choose this MET file in your MET database if you avail of a specific meteo already imported from a given meteo source.

If not, PVsyst will automatically create a synthetic file based on the monthly data of your project's site.

The montly values of the SIT file of the project are not used in the simulation process. But they are important for 2 reasons:

- If you don't avail of meteo hourly data, they will be used for the Synthetic generation,

- Although not necessarily identical to your MET data, these values should be existing and realistic as they are used in the sizing tools like the orientation optimization or the histogram for the sizing of the inverter (i.e. only used for decision makings during the sizing process).