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SoDa-Helioclim Data

SoDa: Solar Data portal

The SoDa Service is located at www.soda-pro.com and offers an access to a large set of information relating to solar radiation. It provides weather data from different sources, mainly from the Helioclim-3 database. The data are computed from METEOSAT meteorological geostationary satellite images, processed with the heliosat-2 method. SoDa proposes also a climatic data bank in monthly values, with irradiance and temperature, averaged over the years 1990 to 2004.

The Helioclim-3 database was initially managed by Mines PariTech but is now owned by Vaisala.

Services available from the SoDa portal

Most services are accessible through a paid membership but demo access is possible for years 2004-2005 for most data. The main available datasets are:

  • HelioClim 3: For data monitoring or prospection, covering Europe and Africa. Data has 1 minute time step to monthly values, for the horizontal global irradiance, the normal beam irradiance, and the global, beam and diffuse on inclined surfaces.
  • Photosynthetically Active Radiation (PAR): spectral range of solar radiation from 400 to 700nm, derived from HelioClim-3 version 5. Covers Europe, Africa, Atlantic Ocean, Middle East. Spatial resolution is ~3 km.
  • MERRA-2: Worldwide since 1980. Temperature, relative humidity, pressure, wind speed and direction, rainfall, snowfall, snow depth and Global Horizontal Irradiation (GHI). Time steps range from 1 min to 1 month, with a spatial resolution of ~50 km.
  • TMY: Typical Meteorological in hourly steps for 3 different scenario, derived from HelioClim-3 and MERRA:
    • median e.g. Percentile 50
    • pessimistic e.g. Percentile 75
    • optimistic e.g. Percentile 10.
  • Monthly values: Worldwide means of solar irradiance (downwelling shortwave irradiance), daily minima, maxima and mean values of air temperature at 2 m, and daily minima, maxima and mean of relative humidity at 2m, averaged over the period 1990-2004 (15 years). Data processed from fusion techniques applied to satellite data, meteorological re-analyses from NCEP / NCAR (USA) and orography.

Details of the Heliosat-2 method

The Helioclim-3 data bank is produced with the Heliosat-2 method that converts observations made by geostationary weather data satellites into estimates of the global irradiation at ground level. This version integrates the knowledge gained by various exploitations of the original Heliosat method and its varieties in a coherent and thorough way.

It is based upon the same physical principles as for Solargis, but the inputs to the method are calibrated radiances, instead of the digital counts output from the sensor. This change opens the possibilities of using known models of the physical processes in atmospheric optics, thus removing the need for empirically defined parameters and of pyranometric measurements to tune them. The ESRA models are used for modeling the clear-sky irradiation. The assessment of the ground albedo and the cloud albedo is based upon explicit formulations of the path radiance and the transmittance of the atmosphere. The turbidity is based on climatic monthly Linke Turbidity coefficients data banks.

The Liu and Jordan (1960) model is used to split the global irradiance into the diffuse and beam components.

Importing SoDa-Helioclim data

Monthly data

Be aware when using monthly values that:

  • Irradiance is given in average W/m2 per month when PVsyst expects the summed irradiance in kWh/m2 per month. Conversion is required
  • Data is average over 1990-2004, which can be inaccurate in places most affected by climate change.

TMY

TMY datasets should be available in the PVsyst standard format and can be imported via the "known format" procedure.

Time-series

Other time series can be exported as .csv files but they are not in the PVsyst standard format. These datasets should be imported as custom files