Skip to main content
EU Science Hub

Daily radiation

In this section of PVGIS we show the average solar irradiation for each hour during the day for a chosen month, with the average taken over all days in that month during the multi-year time period for which we have data. In addition to calculating the average of the solar radiation, the daily radiation application also calculates the daily variation in the clear-sky radiation, both for fixed and for sun-tracking surfaces. The calculations are made by with the full temporal coverage of the radiation database chosen. The clear-sky estimations are only available for Europe and Africa.

The tool can be accessed with:

Outputs

The daily radiation data consists of 24 hourly values of the average solar irradiance (and optionally temperature) at each hour for a given month. The curve of hourly values is termed the "daily profile".

 

csv

The data format consists of a header followed by 24 hourly sets of values, each hour on a separate line. The header contains the following information on separate lines:

  • Latitude (in decimal degrees)
  • Longitude (in decimal degrees)
  • Name of the solar radiation database used
  • One empty line
  • Month for which the calculation is made (name of month in English)
  • Slope (inclination, in degrees) angle for the fixed plane irradiance
  • Azimuth/orientation (in degrees) angle for the fixed plane irradiance

There is one line of header for the table, followed by the 24 lines of data, with the columns in the following order:

  • time [hour:minute] - in UTC or local timezone time, according to the choice of the user
  • G(i), Gb(i), Gd(i) [W/m2] - Global, direct, and diffuse irradiance on a fixed plane
  • Gcs (i) - Global clear-sky irradiance on a fixed plane
  • G(n), Gb(n), Gd(n) [W/m2] - Global, direct, and diffuse irradiance on a 2-axis tracking plane
  • Gcs(n) [W/m2] - Global clear-sky irradiance on a 2-axis tracking plane
  • T2m [°C] - Air temperature

If any of these fields were not selected in the call to the PVGIS server, they will not appear in the output. For example, if you selected fixed-plane irradiance and clear-sky irradiance as well as the temperature, but NOT the 2-axis radiation, the temperature will be in column 6, after time, global, direct, and diffuse irradiance, and the clear-sky irradiance value.
Note that you cannot select the global, direct, and diffuse values separately.
The table is followed by a few lines of explanation.

 

json

{    "inputs": {        "location": {
           "latitude": 45.809,
           "longitude": 8.632,
           "elevation": 223        },
        "meteo_data": {
           "radiation_db": "PVGIS-SARAH",
           "meteo_db": "ERA-Interim",
           "year_min": 2005,
           "year_max": 2016,
           "use_horizon": true,
           "horizon_db": "DEM-calcualted",
        },
        "plane": {
            "fixed": {
                "slope": {
                    "value": 35,
                    "optimal": "-"                },
                "azimuth": {
                    "value": 0, 
                    "optimal": "-"                },            },            "two_axis": {
                "slope": {
                    "value": "-",
                    "optimal": "-"                },
                "azimuth": {
                    "value": "-", 
                    "optimal": "-"                },            },
        },        "time_format": "UTC",    },

    "outputs": {
        "daily_profile": {
            {
                "month": 1,
                "time": "00:00",
                "G(i)": 0,
                "Gb(i)": 0,
                "Gd(i)": 0,
                "Gcs(i)": 0,
                "G(n)": 0,
                "Gb(n)": 0,
                "Gd(n)": 0,
                "Gcs(n)": 0,
                "T2m": 2.13,
            },
            {...}
        }
    },

    "meta": {        "inputs": { 
            "location": {
                "description": "Selected location"
                "variables": {
                    "latitude": {
                        "description": "Latitude",
                        "units": "decimal degrees"
                    }, 
                    {...}
                }
            },
            {...}
        },
        "outputs": { 
            "daily_profile": {
                "type": "time series" 
                "timestamp": "hourly"
                "variables": { 
                    "G(i)": { 
                        "description": "Global irradiance on a inclined plane", 
                        "units": "W/m2"                    }, 
                    {...}            },
            {...}
        }
    }
}