The dataset includes daily values of total solar energy received by a horizontal surface in the Athens area, expressed in MJ/m², covering a 20-year period from 2001 to 2020. The calculations were based on data from the actinometric station of the National Observatory of Athens in Thissio (latitude: 38.972° N, longitude: 23.717° E). For each of the days under consideration, the values of the total incident solar radiation on a horizontal surface were collected at 1-hour intervals, expressed in W/m², where, using an appropriate integration method (the trapezium method), the daily integral was calculated, i.e., the total daily energy (in MJ/m²) received by a horizontal surface of unit area exposed to the sun, a parameter useful in studies of climate, building energy efficiency, and PV systems performance.
Finally, for each day of the study period, additional key astronomical parameters are provided, such as the times of sunrise and sunset at the station’s specific geographic location, as well as the time at which the sun reached its highest point in the sky. The time of sunrise at the study site was defined as the moment when the first non-zero value of incoming solar radiation is recorded at the upper limit of the atmosphere, while the time of sunset at the study site was defined as the moment when the last non-zero value of solar radiation is recorded at the upper limit of the atmosphere. Furthermore, at the station’s geographical location, the hourly angle of sunrise has been calculated for each day, from which the theoretically maximum duration of sunshine, expressed in hours, has been derived. The solar constant used in the astronomical calculations is Isc = 1361 W/m². Times are expressed in fixed local time, i.e., Local Standard Time (LST=UTC+2h) of the actinometric station of the National Observatory of Athens in Thissio.
The dataset includes daily values of total solar energy received by a horizontal surface in the Athens area, expressed in MJ/m², covering a 20-year period from 2001 to 2020. The calculations were based on data from the actinometric station of the National Observatory of Athens in Thissio (latitude: 38.972° N, longitude: 23.717° E). For each of the days under consideration, the values of the total incident solar radiation on a horizontal surface were collected at 1-hour intervals, expressed in W/m², where, using an appropriate integration method (the trapezium method), the daily integral was calculated, i.e., the total daily energy (in MJ/m²) received by a horizontal surface of unit area exposed to the sun, a parameter useful in studies of climate, building energy efficiency, and PV systems performance.
Finally, for each day of the study period, additional key astronomical parameters are provided, such as the times of sunrise and sunset at the station’s specific geographic location, as well as the time at which the sun reached its highest point in the sky. The time of sunrise at the study site was defined as the moment when the first non-zero value of incoming solar radiation is recorded at the upper limit of the atmosphere, while the time of sunset at the study site was defined as the moment when the last non-zero value of solar radiation is recorded at the upper limit of the atmosphere. Furthermore, at the station’s geographical location, the hourly angle of sunrise has been calculated for each day, from which the theoretically maximum duration of sunshine, expressed in hours, has been derived. The solar constant used in the astronomical calculations is Isc = 1361 W/m². Times are expressed in fixed local time, i.e., Local Standard Time (LST=UTC+2h) of the actinometric station of the National Observatory of Athens in Thissio.
![[Open Data]](/images/png/open-data.png)