Comparison analysis of the glazed and unglazed curved water-based PV/T roofs in the non-heating season

Abstract

Curved tile rooftops are a characteristic design in traditional Chinese architecture. Building-integrated photovoltaic/thermal (BIPV/T) systems could realize electricity generation and energy conversion, but the common flat-type structure could not integrate with the curved rooftops while keeping the architectural features. This study proposed a curved water-based PV/T roof combined with flexible PV cells to generate electricity, provide hot water in the non-heating season, and maintain the curved roof structure. An integrated polymethyl methacrylate (PMMA) cover was installed on the comparative test rig to investigate its influence on the system's performance. Numerical models were established to describe comparative systems' behavior and validated by experimental data. The results showed that PMMA cover would increase the system's thermal efficiency and decrease the electrical efficiency (electrical efficiency: 5.56% for the unglazed system and 4.80% for the glazed system; thermal efficiency: 33.32% for the unglazed system and 56.01% for the glazed system). Among non-heating seasons, the electrical yield, heat gain and exergy by the unglazed system are 82.49 kWh, 288.29 kWh and 87.87 kWh, while those by the glazed system are 67.21 kWh, 506.93 kWh and 83.67 kWh respectively. Influence of PMMA cover's extinction coefficient and the curvature of the PV/T unit is discussed.