Solar calculator

Solar calculator

Solar Calculator

To compute direct and diffuse irradiance over an arbitrarily oriented slope, fill in or modify the values below. The model computes potential solar radiation for clear skies, it does not take into account terrain obstruction, shading or clouds. To incorporate those effects for specific studies, please contact us.

Site name Latitude Longitude Timezone Year Month
Day Interval in minutes [5-60] Slope [0-90] Aspect [0-360] Altitude Visibility [km]
Relative Humidity [%] Temperature [°C] Ozone thickness [DU] Ground albedo [0.0 - 1.0]

Location is the name of the site, can be real or imaginary, it is used only for reference. Must be only alphanumeric characters.

Latitude: the geographical latitude in degrees and decimal degrees. Values must be in the range -90 to 90.

Longitude: the geograpical longitude in degrees and decimal degrees. Values must be in the range -180 to 180.

Timezone: the timezone, leave it at 0 for UTC.

Year: year in the range 1801 - 2099. This tool is not for paleoclimate calculations.

Month: month in the range 1 - 12.

Day: day of the month, from 1 to 31 (choosing the 31st of February will return the 3rd of March on non-leap years).

Interval in minutes: Time interval for calculation, range 0 - 60, every five minutes to every hour.

Slope: slope tilt (0-90), inclination of the surface or panel with respect to the horizontal, 0° is flat 90° is completely vertical.

Aspect: slope orientation (0-360), orientation of the surface, solar panel, roof, etc. If looking north it will be 0°, if looking south it will be 180° (do not insert the degree symbol).

Altitude (m): elevation above sea level in metres.

Visibility (km): it is the maximum distance in km where large objects can be distinguished in the horizon. The value given (50 km) is for a clean atmosphere. This is a proxy for atmospheric turbidity, it is choosen as many airports report visibility, while other parameters, such as Linke Turbidity, are more difficult to obtain. Airport reports (METAR) are given here or here among other sites.

RH (%): Relative Humidity in percentage, values from 0 to 100. Airport reports (METAR) normally include RH.

Temperature °C: temperature in degrees centigrade.

Ozone thickness (DU): ozone layer thickness in Dobson Units. Divide Dobson Units by 100 to get the equivalent in mm. Check the TOMS (Total Ozone Mapper Spectrometer) pages for current values.

Ground Albedo: albedo of the surrounding terrain, e.g. 0.8 to 0.95 for fresh snow, 0.17 for deciduous forest, 0.35 for sand, etc.



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