Field experimental investigation of a multifunctional curved CIGS photovoltaic/thermal (PV/T) roof system for traditional Chinese buildings

Abstract

To manifest the traditional Chinese architectural aesthetics with curved elements and realize multiple functions, the curved photovoltaic/thermal (PV/T) technology needs to be developed urgently. Inspired by traditional Chinese buildings, a multifunctional curved Copper Indium Gallium Selenide (CIGS) PV/T roof system is proposed. The system can fit the pitched tile roof well while providing electrical power, hot water/air, and improving interior ventilation according to domestic use by switching among four operation modes—PV/water-heating mode, PV/air-heating mode, PV-natural ventilation mode, and PV/water-natural ventilation mode. The last two modes can improve electrical efficiency and interior ventilation through natural ventilation comparatively. Two independent systems are used to investigate the influence of the Polymeric methyl methacrylate (PMMA) cover, the air fans and water pumps with different powers on the systems' electrical and thermal performance. The comprehensive analysis of the experimental results indicates that the system is reliable and multifunctional. A new efficiency evaluation method for the curved PV/T roof is proposed. The test rig was established, and the field experiments were conducted. Results show that in PV/water-heating mode, the average electrical efficiency is 6.57%, and the daily thermal efficiency is 25.28%; in PV/air-heating mode, the average electrical efficiency reaches 5.68%, and the thermal efficiency is 39.62%. The comparative experiments show that the relative increase in electrical efficiency is 6.93% in PV-natural ventilation mode and 1.93% in PV/water-natural ventilation mode.