Here are some verified C codes developed by us in different application. It can be downloaded and use unrestricted for scientific applications.
1. ProgFuzzy is a C code that calculates the global solar irradiation using air temperature data via fuzzy procedures . More …
2. EffectiveIrrad is an exe file that calculates the biologically effective solar irradiance using a new parameter model. Generalized plant response  action spectrum, plant growth response  and Photosynthetically Active Radiation (PAR) are implemented. More …
For questions, comments:
 E. Tulcan-Paulescu, M. Paulescu (2008) Fuzzy modeling of solar irradiation using air temperature data, Theor Appl Climatol 91, 181-192.
Caldwell, M. M. (1971) Solar Ultraviolet Radiation and the Growth and
Development of Higher Plants. In Photophysiology (Edited by A. C. Giese) pp. 131-177, Academic Press,