Astronomic Sun Tracker Performance and Solar Energy Collection Comparison for Different Italian Sites

In many Mediterranean Countries the level ofsolar insolation on horizontal varies from 4 to 5.5 MJ/(m day), as annual average. When the beam fraction of the solar energy is predominant, tracking the solar disk is a possible strategy to increase the energy yield in PV and thermal solar systems. This paper is addressed to the comparison (in terms of collectable energy) among feedback, double axis, trackers and a particular single axis one, driven by astronomic information. The comparison is made in terms of hourly simulations, based on TMY solar data. The reference tracker is assumed to be able to minimize the surface zenith angle and even to orient the collectors horizontally under cloudy conditions. The results show that the differences (reference vs astronomic) in yearly collectable energy are within few percent, thus demonstrating that non concentrating solar systems can be successfully applied with simple, astronomic tracking devices.