A Building-Integrated Hybrid Photovoltaic-Thermal (PV-T) Window for Synergistic Light Management, Electricity and Heat Generation

The installation of common solar panels and collectors in the built environment requires access to significant roof space, which is limited. This motivates the development of high-efficiency, building-integrated technologies that can maximize space utilization and energy provision. In this work, a building-integrated hybrid photovoltaic-thermal window (PVTW) is fabricated and tested, composed of a semi-transparent photovoltaic (PV) layer and a selectively absorptive liquid-based thermal absorber. It is demonstrated that, at 30 degrees inclination, the PVTW can simultaneously generate electricity, with an electrical efficiency of 3.6%, and provide approximate to 50 degrees C water, with a thermal efficiency of 10.7%, in the middle of a typical summer day (20th July) in London (maximum ambient temperature approximate to 34 degrees C, solar irradiance approximate to 1100 W m-2 at midday). The water temperature decreases by approximate to 7 degrees C, whilst thermal efficiency improves to 17.6% as the inclination angle increases to 90 degrees (vertical); the electrical efficiency reduces marginally (3.3%). Compared to a liquid-based solar-thermal window (STW), the PVTW can generate hot water at approximate to 10 degrees C higher temperature and with 10% absolute increase in thermal efficiency when the inclination angle is 60 degrees, plus electricity. The wider uptake of this technology in glass-based urban spaces has the potential to generate significant energy while reducing building temperature management costs.