SunCalculator is a computer program that calculates the angular and spectral distribution of measured integrated solar irradiance. It can be used to generate realistic light sources for ray tracing applications.

SunCalculator generates binned output files of the segmented celestial hemisphere. Each of the segments contains information about the integrated direct and diffuse irradiance, as well as the direct and diffuse spectral distribution.

SunCalculator includes a pre-calculated SMARTS database (Filename: SMARTS_fine.bin). It is mandatory to accept the SMARTS license agreement prior using the SMARTS database within SunCalculator. The program can be used for free, however it must be registered prior first use. By using SunCalculator, the User accepts the license agreement included in the download.

The latest release (2.9) has added some new features and improvements:

  • Automatic updates and license management (licenses remain free, but registering is required)
  • Modifying the acceptance angle of direct normal irradiance (DNI) measurements improves the angular distribution calculation
  • The turbidity factor used in the angular distribution calculation is now user-modifiable
  • Added support of typical meteorological year files and "pass-through" of other meteorological parameters
  • Several bugfixes

The reference below gives a full description of the calculation procedure as well as example applications.

Download References

SunCalculator (Version 2.9)

New release 26/06/2019!

Manual (Version 1.1)

Note: The manual version 1.1 is referring to SunCalculator 2.7. An updated manual describing all new features is in progress.

License Agreement

  M. Ernst, H. Holst, M. Winter, and P. P. Altermatt, “SUNCALCULATOR: A program to calculate the angular and spectral distribution of direct and diffuse solar radiation,” Sol. Energy Mater. Sol. Cells 157, 913–922 (2016),

Wed Jun 26, 2019

SunCalculator Photon flux, integrated over all wavelengths and binned, as calculated empirically for 14 years of irradiance measurements in Hamelin, Germany. Clear sky global irradiance calculated for south-facing module tilted by 32° in module coordinates for Hamelin, Germany.