Monthly radiation

Here we calculate the monthly averages of solar radiation for the chosen location, showing in graphs or tables how the average solar irradiation varies over a multi-year period. The results are given for radiation on horizontal and/or inclined planes, as well as Direct Normal Irradiation (DNI).

The tool can be accessed with:

• PVGIS interface - Monthly data tab
• Non-interactive service - MRcalc app

Outputs

The monthly radiation data output produces average values for each month of a period spanning one or more years.

csv

The output format consists of a header with general information followed by the monthly time series of data. The fields in the output format are the following:

Header

• Latitude (in decimal degrees)
• Longitude (in decimal degrees)
• Name of the solar radiation database used
• Optimal inclination angle (this line is present even if the optimum angle radiation was not selected)
• One empty line
• Header line for the time series

Monthly data: TheMRcalc data for each month are written on a single line, separated by (→). The data fields are:

• year
• month
• H(h)_m [kWh/m2/mo] - Global horizontal irradiation
• H(i_opt)_m [kWh/m2/mo] - Global irradiation on optimally inclined plane
• H(i)_m [kWh/m2/mo] - Global irradiation on inclined plane
• Hb(n)_m [kWh/m2/mo] - Direct normal irradiation
• Kd [-] - Ratio of diffuse to global horizontal irradiation
• T2m [°C] - Air temperature

If any of the fields were not selected they will not appear in the output, and the number of columns will be reduced accordingly. For example, if the global horizontal irradiation was not selected but the optimum angle irradiation was selected, the latter will be in the third column in the output (after year and month).
The last part of the output consists of a line of explanation for each field that is present in the output.

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(h)": {
                "slope": {
                    "value": 0,
                    "optimal": "-"                },
                "azimuth": {
                    "value": 0, 
                    "optimal": "-"                 },            },
            "fixed(i)": {
                "slope": {
                    "value": 30,
                    "optimal": "-"                },
                "azimuth": {
                    "value": 0, 
                    "optimal": "-"                 },            },
            "fixed(i_opt)": {
                "slope": {
                    "value": 41,
                    "optimal": true
                },
                "azimuth": {
                    "value": 0, 
                    "optimal": "-"                 },            },
        },    },

    "outputs": {
        "monthly": {
            {
                "year": 2005,
                "month": 1,
                "H(h)_m": 58.51,
                "H(i_opt)_m": 134.26,
                "H(i)_m": 118.22,
                "Hb(n)_m": 140.78,
                "Kd": 0.29,
                "T2m": 1.2            },
            {...}
        }
    },

    "meta": {        "inputs": { 
            "location": {
                "description": "Selected location"
                "variables": {
                    "latitude": {
                        "description": "Latitude",
                        "units": "decimal degrees"
                    }, 
                    {...}
                }
            },
            {...}
        },
        "outputs": { 
            "monthly": {
                "type": "time series" 
                "timestamp": "monthly averages"
                "variables": { 
                    "H(h)_m": { 
                        "description": "Monthly global irradiation on a horizontal plane", 
                        "units": "kWh/m2/mo"                    }, 
                    {...}            },
            {...}
        }
    }
}