Weather Data Note 1: Monthly & Hourly Weather data files (.SIT/.MET)

PVsyst distinguishes two kinds of weather data:

Monthly weather data

*.SIT files, which are associated with every geographic site. Monthly data are used to build the hourly data.

Monthly weather data files contain :

the site name, the country, the world region
the geographical coordinates: latitude, longitude, altitude and Timezone.
the monthly Global Horizontal Irradiation (GHI or GlobHor)
the monthly averages of the ambient temperature

The files may also include optional data :

the monthly Diffuse Horizontal Irradiation (DiffHor)
the monthly average of Wind Velocity.

They can be defined :

from the Geographical sites section using PVsyst routines
from the Import weather data section using external sources

You are advised to carefully define the source of the data. Read also our note on horizon in weather data files.

*.SIT files are stored in the \Data\Sites\ directory.

Hourly weather data

*.MET files, which are used by the simulations.

Hourly weather data contains the hourly values of :

Global Horizontal Irradiation (GlobHor or GHI) ,
Diffuse Horizontal Irradiation (DiffHor),
Ambient temperatures,
Wind Velocity if available

The data are recorded for whole days (0H .. 23H). Step labels are referred to the beginning of the interval (i.e. the 12 h label corresponds to the 12-13 h interval). A complete file for one year occupies about 70 kB (53 kB without wind-velocity). When importing your own measurements, the weather data file can be restricted to limited periods, and even have full-days holes. In this case the date is included in each record on the file.

Hourly weather data can be obtained:

from the Synthetic hourly data generation section
from the Import weather data section using external sources
from the Import ASCII weather data file section.

The characteristics and contents of hourly weather data files (*.MET files) can be visualized and analyzed thanks to the weather data tables and graphs tool.

The hourly weather data files (*.MET files) are stored in the \Data\Meteo directory.