In this paper, work is carried out in three steps. In the first step, optimization of single channel glazed photovoltaic thermal (SCGPVT) array has been done with an Evolutionary Algorithm (EA) keeping the overall exergy gain is an objective function of the SCGPVT array. For maximization of overall exergy gain, total seven design variables have been optimized such as length of the channel (L), mass flow rate of flowing fluid (m(F)), velocity of flowing fluid (V-F), convective heat transfer coefficient through the tedlar (U-T), overall heat transfer coefficient between solar cell to ambient through glass cover (U-SCAG), overall back loss heat transfer coefficient from flowing fluid to ambient (U-FA) and convective heat transfer coefficient of tedlar (h(T)). It has been observed that the instant overall exergy gain obtained from optimized system is 1.42 kWh, which is 87.86% more than the overall exergy gain of a un-optimized system given in literature. In the second step, overall exergy gain and overall thermal gain of SCGPVT array has been evaluated annually and there are 69.52% and 88.05% improvement in annual overall exergy gain and annual overall thermal gain respectively than the un-optimized system for the same input irradiance and ambient temperature. In the third step, carbon credit earned by the optimized SCGPVT array has also been evaluated as per norms of Kyoto Protocol Bangalore climatic conditions. (C) 2015 Elsevier Ltd. All rights reserved.