Evaluation of the direct and diffused component of solar radiation starting from global radiation measurements: Preliminary analysis

Abstract

This article aims to devise an analytical methodology suitable for assessing the various components of the solar radiation (direct, diffused by the sky vault, reflected by the ground and other surrounding surfaces). As input, it uses measured data of the global solar irradiance coming from six perpendicular space directions (South, North, Est, West and the two vertical directions). Assessing the contribute of the component of solar radiation which is reflected by the surrounding surfaces on a horizontal plane, the proposed method is suited to being applied in areas (e.g. urban settings) where an optimal installation of the measurement apparatus (devoid of objects reflecting solar radiation) is not possible. Furthermore, it allows the actual sky view factor to be taken into account, so that the influence of objects or surfaces, partially shading the view of the sky is evaluated. In addition, the experimental apparatus generally used for the assessment of the mean radiant temperature in outdoor environment may be exploited, thus allowing a more comprehensive control of the climate conditions of the analysed site.