Weather data Custom file - Format file .MEF

The format file defines all characteristics governing the custom source file reading (Weather data or Measured data files).

The format of the source-file may be very varied; however it has to fulfil the following minimal criteria:

• Include the values of one time step (hourly or sub-hourly) per text line. Each line ends with the characters CR,LF, or only LF.
  • Sub-hourly records are gathered in order to give PVsyst hourly internal records.
• Comment lines at the beginning of the file, or of each day or month, can be skipped.
• Data are organized in columns, with a chosen separator (semi-colon, comma, TAB, blank, etc. ) or fixed widths. PVsyst accepts a great variety of date formats, and adjusts the source data physical units.
• The available parameters should include the minimal data which allow the calculation of the horizontal global and the ambient temperature.
  • Since simulation also requires the horizontal diffuse irradiation, this is calculated, for example, horizontal global and beam data. If not available, the diffuse irradiation is reconstituted using the Erbs correlation.
• With measured data, if only the irradiation in the collector plane is available, the program calculates the corresponding horizontal global and diffuse (inverse of the transposition).
  • Nevertheless, due to edge effects, these data will only be valid within the original collector plane.
• Usually the values are consecutive; but if values are missing on the source file (for example night values), the date should be explicitly mentioned on each line of data.
  • Given that the internal file must hold complete days, the data for any missing hour will be completed with zero irradiation values.
• Gaps of more than one day may be acceptable with the option of writing the date for each reading on the internal file.
• It is also possible to automatically chain data monthly or daily files, provided that their name include exploitable identification code (date).