Hindawi Publishing Corporation Journal of Thermodynamics Volume 2009, Article ID 313561, 11 pages doi:10.1155/2009/313561 Research Article Exergetic Optimization of a Solar Photovoltaic Array Faramarz Sarhaddi, Said Farahat, Hossein Ajam, and Amin Behzadmehr Department of Mechanical Engineering, Shahid Nikbakht Faculty of Engineering, University of Sistan & Baluchestan, Zahedan 98164-161, Iran Correspondence should be addressed to Faramarz Sarhaddi, fsarhaddi@eng.usb.ac.ir Received 5 June 2009; Revised 20 September 2009; Accepted 6 November 2009 Recommended by Marc A. Rosen An exergetic optimization is developed to determine the optimal performance and design parameters of a solar photovoltaic (PV) array. A detailed energy and exergy analysis is carried out to evaluate the electrical performance, exergy destruction components, and exergy efficiency of a typical PV array. The exergy efficiency of a PV array obtained in this paper is a function of climatic, operating, and design parameters such as ambient temperature, solar radiation intensity, PV array temperature, overall heat loss coefficient, open-circuit voltage, short-circuit current, maximum power point voltage, maximum power point current, and PV array area. A computer simulation program is also developed to estimate the electrical and operating parameters of a PV array. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, exergetic optimization has been carried out under given climatic, operating, and design parameters. The optimized values of the PV array temperature, the PV array area, and the maximum exergy efficiency have been found. Parametric studies have been also carried out. Copyright © 2009 Faramarz Sarhaddi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. Introduction Renewable energies are going to be a main substitute for fossil fuels in the coming years for their clean and renewable nature. A solar photovoltaic (PV) array is one of the most significant and rapidly developing renewable-energy technologies, and its potential future uses are notable. PV array is a semiconductor device, which converts light energy directly into useful electricity. The energy payback time (EPBT) of a PV system lies between 10 and 15 years depending on insulation and the performance of it. If the performance of a PV array can be increased, the energy payback time can be reduced. Therefore, the optimized performance evaluation of a PV array is important. PV array performance parametrically depends on cli- matic, operating, and design parameters such as ambient temperature, solar radiation intensity, PV array temperature, overall heat loss coefficient, open-circuit voltage, short- circuit current, maximum power point voltage, maximum power point current, and PV array area. It can be evaluated in terms of energy efficiency and exergy efficiency. Its evaluation based on the first and second laws of thermodynamics is known as energy efficiency and exergy efficiency, resp- ectively. The energy analysis has some deficiencies [1, 2]; funda- mentally, the energy concept is not sensitive with respect to the assumed direction of the process; for example, energy analysis does not object if heat is considered to be transferred spontaneously in the direction of increasing temperature. It also does not distinguish the quality of energy; for example, 1 W of heat equals 1 W of work or electricity. Energy analyses on their own incorrectly interpret some processes [1, 2]; for example, environmental air, when isothermally compressed, maintains its energy (e.g., enthalpy) equal to zero, whereas the exergy of the compressed air is greater than zero. However, exergy data are more practical and realistic in comparison with the respective energy values. Thus, exergy analysis usually provides a more realistic view of process than energy analysis; some times, they are different [1, 2]. The energy conversion factor of a solar PV system some- times is described as efficiency, but this usage sometimes leads to some difficulties such as follows [3]. The energy