Comments on “Entransy analysis of irreversible Carnot-like heat engine and refrigeration cycles and the relationships among various thermodynamic parameters” (Emin Açıkkalp, Energy Convers. Manage. 80 (2014) 535–542) and “Entransy analysis of irreversible

The electrical efficiency of photovoltaic (PV) module can be increased by reducing the operating temperature of PV module. The hybrid photovoltaic/thermal (PV/T) solar system consists of conventional PV module and attached heat transfer pipe with internal working fluid flowing to extract heat energy from PV module. This article presents a brief review on the latest researches and applications of the PV/T systems. Afterwards, based on energy-balance equations, mathematical models for several PV/T systems with different configurations are developed. Analytical expressions for both the electrical and thermal performance parameters are derived as functions of climatic and design parameters to conduct comparative analyses. The calculation results indicate that the changes in the PV/T configurations have influences on electrical and thermal performances of the PV/T system. Further suggestions on configurations optimization for practical applications are propounded.