Measurement of Solar Radiation for Renewable Energy Systems

In this paper the authors present a new set of solar radiation data taken at the latitude of 45.4°, in Padova, Italy. These measurements are performed within a new laboratory for the study of solar energy conversion systems. The global and the diffuse irradiance is measured on the horizontal plane and the global irradiance is also measured on sloped planes. The experimental uncertainty of the measurement of solar radiation is fully analyzed. In the design of a solar system, it is crucial to know the solar radiation on the inclined surface, but generally only data on the horizontal is available and solar radiation on the tilted plane is predicted using the information collected on the horizontal. There is need for assessment of prediction methods for estimating the solar radiation on inclined surfaces. In this paper, new data of global and diffuse radiation is compared to some most used correlations. Besides, the values calculated for the tilted plane are compared against those directly measured by a pyranometer installed on the sloped plane.