insol: Solar Radiation

Calculates insolation on tilted surfaces, computes atmospheric transmittance and related parameters such as: Earth radius vector, declination, sunset and sunrise, daylength, equation of time, vector in the direction of the sun, vector normal to surface, and some atmospheric physics.

Version: 1.2.2
Depends: methods
Imports: raster, rgdal
Suggests: datasets, graphics, rgl, stats
Published: 2020-03-26
Author: Javier G. Corripio
Maintainer: Javier G. Corrripio <jgc at>
License: GPL (≥ 2)


Package source: insol_1.2.2.tar.gz
Reference manual: insol.pdf
Vignette: insol-V.pdf


April, 2013

A new updated version 1.1 is available above and in the CRAN repository.

January 2019

Updated version 1.2

March 220

Updated version 1.2.2



Corrected in version 1.2

Corrected in version 1.2.2



Bird, R. E. and Hulstrom, R. L. (1981a) Review, evaluation and improvements of direct irradiance models, Trans. ASME J. Solar Energy Eng. 103, 182-192.

Bird, R. E. and Hulstrom, R. L. (1981b) A simplified clear sky model for direct and diffuse insolation on horizontal surfaces, Technical Report SERI/TR-642-761, Solar Research Institute, Golden, Colorado. pdf

Bourges, B.: 1985, Improvement in solar declination computation, Solar Energy 35(4), 367-369.

Corripio, J. G.: 2003, Vectorial algebra algorithms for calculating terrain parameters from DEMs and the position of the sun for solar radiation modelling in mountainous terrain, International Journal of Geographical Information Science 17(1), 1-23. pdf

Danby, J. M. Eqn. 6.16.4 in Fundamentals of Celestial Mechanics, 2nd ed. Richmond, VA: Willmann-Bell, p. 207, 1988.

Iqbal, M. (1983) An Introduction to Solar Radiation, Academic Press, Toronto.

Meeus, J. 1999. Astronomical Algorithms. Willmann-Bell, Richmond, Virginia, USA.

Reda, I. and Andreas, A. 2003. Solar Position Algorithm for Solar Radiation Applications. 55 pp.; NREL Report No. TP-560-34302, Revised January 2008.


Hillshading of mountain relief in the Pyrenees.

Shadow cast by a pyramid with the sun at 15° elevation, 315° azimuth

Cumulative insolation over a day in spring on the island of La Palma, Canary Islands.


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