Helioclim-3 Real Time and Forecast - USAGE

Last update: Jul. 2017 Back to Web service >>

    Introduction - Inputs - Outputs

Introduction

This service provides HelioClim-3 version 4 radiation values estimated from satellite imagery for today and tomorrow. The Web interface is available for free, and the automatic access requires that you subscribe an annual subscription. Please    to receive a quotation.

Please note that this interface addresses two different services:

Data for today: real time and persistence model

As soon as a new Meteosat image is available every 15 min, the HelioClim-3 database is updated in real time. To receive a time series covering the whole current day, we decided to complete the time series by applying a persistence model. Please find more information about:

Data for tomorrow: similarity forecast model

This method explores the HelioClim-3 database to find for similar meteorological events in the past in order to make an estimation of the next day irradiation values. Please find more information about:

Inputs

  • HelioClim-3 versions: forecast is available for version 4 only.
  • Add Meteo Data: include (or not) meteo data More information on meteo data
  • Forecast Version: two options are available: "Persistence Forecast" (current day only) or "Similarity Forecast" (for day+1).
    NB: when "Similarity Forecast" is selected and the dates cover today and tomorrow, the service uses the Persistence model to provide the irradiation values for the current day and the similarity forecast model to cover tomorrow.
  • Latitude and longitude: enter the values in decimal degrees (we advise 3 or 4 digits after comma), or directly click on the map to select your point, or you can also use the "Search Address" tool on the top of the map.
  • Altitude: enter the altitude, or let us use our default high resolution elevation database SRTM (spatial resolution 90 m, uncertainty 10 m) by letting the default "Automatic" value.
  • Start date and End date: format yyyy-mm-dd.
  • Time step: "1 min", "5 min", "10 min", "15 min", "30 min", "hour", or "day".
  • Time reference: "UT" or "TST". More information on time references
  • Compute relief shadows: take into account (or not) the shadowing effect due to the far horizon.
  • Plane mode: "Horizontal Plane", "Fixed tilted plane", "2D Sun Tracking (DNI)", "1D Sun Tracking (North-South axis)", "1D Sun Tracking (East-West axis)", "1D Sun Tracking (Tilt tracking)", "1D Sun Tracking (Azimuth tracking)". Fore more details on how to set the tilt, azimuth and albedo parameters, please take a look to the plane mode table available below.
    If you need more information on the radiation components you need, please refer to the illustrations about plane orientations and radiation components. Please check also the azimuth convention adopted by SoDa
  • Output format: Classic CSV Format or Unified CSV Format More information on outputs
 

+ Add Meteo data

Meteo data from GFS (NCEP) can be retrieved.

NB: When "+ Add meteo data" is selected, the new Unified CSV Format is selected by default.

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Plane mode               

(More information on plane orientations and radiation components)  

         Plane mode Tilt (degrees) Azimuth (degrees) Albedo Animations
June 21st Dec. 21st
Horizontal Plane 0 NA NA See animated GIF See animated GIF
Fixed tilted plane <user setting> <user setting> <user setting> See animated GIF See animated GIF
2D Sun Tracking (DNI) Sun Tracking Sun Tracking <user setting> See animated GIF See animated GIF
1D Sun Tracking (North-South axis) Sun Tracking 90° or 270° <user setting> See animated GIF See animated GIF
1D Sun Tracking (East-West axis) Sun Tracking 0° or 180° <user setting> See animated GIF See animated GIF
1D Sun Tracking (Tilt tracking) Sun Tracking <user setting> <user setting> See animated GIF See animated GIF
1D Sun Tracking (Azimuth tracking) <user setting> Sun Tracking <user setting> See animated GIF See animated GIF

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Azimuth convention adopted by SoDa

Firstly, the azimuth convention is:

   Azimuth (degrees) Orientation
North
90° East
180° South
270° West
    

So orientation checking is :

  • A tilted plane is north oriented if azimuth < 90° or azimuth > 270°
  • A tilted plane is south oriented if azimuth > 90° and azimuth < 270°

NB: A plane which is not facing the sun might either be a human error, or may also be due to infrastructure or environmental needs (e.g. part of the rooftop north oriented).

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Outputs

  • Launch: push the "process" button, wait a while and right-click on the appeared link to retrieve your file.
  • Output formats: "Classic CSV" or "Unified CSV Format"
  • Missing data: -999
  • "End of interval" integration hypothesis: the integration hypothesis e.g. hourly data at 11:00 means data averaged over 10:00 to 11:00

  "Classic CSV"

This format is obsolete and won't be maintained since the number and content of the columns change depending on the plane orientation and the time step. Take a look to the column description of "Classic CSV".

  "Unified CSV Format"

This format is simpler which Excel can read seamlessly. It aims at being identical whatever the time step. The consequence is that you can only have two different output columns content: one for horizontal, and another one for all other plane options (fix-tilted, tracking).
NB: When "+ Add meteo data" is selected, new Unified CSV Format is automatically selected.

Horizontal

  1. Date: format yyyy-mm-dd
  2. Time: format HH:MM (no decimal anymore)
  3. Global Horizontal irradiation over the period in Wh/m² (-999 if no data)
  4. Clear-Sky: Irradiation over the period if the sky were clear in Wh/m²
  5. Top of Atmosphere: Irradiation over the period at the top of the atmosphere (extraterrestrial) in Wh/m² computed from Solar Geometry 1
  6. The reliability column has several forms depending of the time step:
    1. Code: 0: no data, 1: sun below horizon, 2: satellite assessment, 5: interpolation in time, 6: forecast
    2. Nb slots (%): ratio of the number of valid slots and the number of slots during the daylength in percent
    3. Nb valid days: number of valid days in the period

Other plane options (fix-tilted, tracking)

  1. Date: format YYYY/MM/DD
  2. Time: format HH:MM (no decimal anymore)
  3. Direct Inclined: irradiation over the period in Wh/m² (-999 if no data)
  4. Diffuse Inclined irradiation over the period in Wh/m² (-999 if no data)
  5. Reflected inclined irradiation over the period in Wh/m² (-999 if no data)
  6. Global Inclined irradiation over the period in Wh/m² (-999 if no data)
  7. Direct Horizontal irradiation over the period in Wh/m² (-999 if no data)
  8. Diffuse Horizontal irradiation over the period in Wh/m² (-999 if no data)
  9. Global Horizontal irradiation over the period in Wh/m² (-999 if no data)
  10. Clear-Sky: Irradiation over the period if the sky were clear in Wh/m²
  11. Top of Atmosphere: Irradiation over the period at the top of the atmosphere (extraterrestrial) in Wh/m² computed from Solar Geometry 1
  12. The reliability column has several forms depending of the time step:
    1. Code: 0: no data, 1: sun below horizon, 2: satellite assessment, 5: interpolation in time, 6: forecast
    2. Nb slots (%): ratio of the number of valid slots and the number of slots during the daylength in percent

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