Exergy efficiency of solar components and systems

Abstract

The solar energy is an inexhaustible source of energy and offers many environmental advantages compared to conventional energy sources. This paper deals with exergy efficiency of solar systems. The exergy is the measure of the maximum useful work which can be achieved by a system having to interact with an environment which is at a constant pressure and temperature. The exergetic analysis or analysis by the Second Law of Thermodynamics, has proven to be a powerful tool for thermodynamic analysis of power systems. In other words, it can be widely used in the assessment and evaluation of processes and the performances of energy systems. Although today many technically and economically successful solar systems are in operation, there is no widely accepted basis for comparison of achieved performances of a solar system with one that runs under different conditions. For this reason, this paper has focused on developing simple methods for assessing and comparing the exergetic efficiencies of the solar systems. There are several ways of using solar energy, and this work is focused on the collectors of solar energy used in solar water heaters, solar cookers, as well as photovoltaic and hybrid solar collectors.