In this paper, Energy, Entropy and Exergy (EEE) analysis of flat plate solar collector is studied through a mathematical model by considering the overall loss coefficient as a non-constant parameter. The overall loss coefficient is calculated by minimizing the top loss coefficient using Lagrange multiplier optimization technique and also by empirical formulas. Further, energy efficiency, entropy generation, exergy destruction and exergy efficiency of the flat plate solar collector are also determined for the both aforesaid overall loss coefficients. The exergy efficiency of the proposed model has been doubled, when compared with the experimental measurements in the earlier literature. Also, comparing the proposed methods, it is observed that exergy efficiency obtained by using the minimal top loss coefficient is reasonably high and it enhances the overall collector’s efficiency.

This study investigates the hidden thermal losses of glass plate, collector plate, water pipe and storage tank of solar water heater in the process of energy conversion. The present non-conventional energy methods are insufficient, whereas the exergy analysis provides a remarkable solution. Thus, employing the exergy analysis, entropy generation, exergy destruction and exergy efficiency of each subsystem of solar water heater are computed. The obtained results showed that the entropy generation and exergy destruction are high during the heat transfer in each subsystem. Henceforth, the existing solar water heater design is modified placing hexagonal honeycomb structure between the glass plate and the collector plate and also water pipe is insulated to trap huge amount of solar energy. The proposed design exhibits improved exergy efficiency when compared with the existing model, which enhances the performance of the system.