Irradiation data, recorded on vertical surfaces facing north, south, east and west and on a horizontal surface every ten minutes during daylight hours from January–December 1992 in Valencia, Spain, have been compared with estimated solar irradiation from inclined-surface models. Results show...

A programme of measurements aimed at originating a database of spectral solar irradiance which is representative of a wide range of optical masses and atmospheric conditions is described. A preliminary analysis of the measurements for clear-sky conditions is also presented.

An automatic global and direct solar spectral irradiance system has been designed based on two LICOR spectroradiometers equipped with fibre optics and remote cosine sensors. To measure direct irradiance a sun tracker based on step motors has been developed. The whole system is autonomous and...

Estimated irradiance values from the Helios model have been compared with experimental global irradiance values on four vertical planes measured in Valencia (Spain). The two versions of the model, based on the CEC and the Perez models for diffuse irradiance estimation, deviate to the same degree...

Data sets of total and direct solar irradiation at Valencia (Spain) measured during the years 1990–1991 have been used to analyze diverse methods of estimating the daily values and monthly average daily values of the diffuse fraction of solar radiation from the ratio of the total to the...