Design, development and characterisation of a Building Integrated Concentrating Photovoltaic (BICPV) smart window system. (15th May 2021)

• Record Type: Journal Article
• Authors: Liu, Xiao; Wu, Yupeng
• Is Part Of: Solar energy. Volume 220(2021)
• Page Start: 722
• Page End: 734
• Publication Date: 2021-05-15
• Subjects: Building Integrated Concentrating Photovoltaic (BICPV) -- Thermotropic membrane -- Ray-tracing -- Optical concentration ratio; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2021.03.037
• Languages: English
• ISSNs: 0038-092X

Abstract

Highlights: A novel BICPV smart window was designed for electricity generation and daylighting control. HPC based thermotropic membrane was selected for the proposed BICPV smart window. A validated ray-tracing program was used to predict the BICPV performance. The BICPV offers higher electricity generation than its counterpart non-concentrating BIPV. Abstract: Building Integrated Concentrating Photovoltaic (BICPV) window represents a promising alternative approach for improving the electricity generation of photovoltaic cells when integrated into building windows. As a new concept, BICPV smart window consisting of an optically switchable thermotropic layer with integrated PV cells offers the potential to simultaneously generate electricity and control solar heat and visible light into buildings. In this study, a BICPV smart window system with a Hydroxypropyl Cellulose (HPC) based thermotropic hydrogel membrane has been developed and characterised. The system was designed with the aid of a validated wavelength-dependent optical model based on a Monte-Carlo ray-tracing technique, where the thermal and optical properties of the thermotropic layer used for the optical model prediction were obtained from experimental measurement. Subsequently, a prototype of the BICPV smart window system has been fabricated and characterised under controlled indoor conditions. From the experiments, it was found that the maximum power output of the BICPV smart window (6 wt% HPC) increases by 17.1% with the membrane temperature increasing from 40 °C (the transition temperature) to 54 °C; meanwhile, a 70.9% reduction in the light transmittance is observed. This indicated that the BICPC smart window might potentially reduce the solar heat gain in hot periods and therefore reduce the building energy demand. In addition, the effect of different concentrations of HPC polymer (2, 4 and 6 wt%) on the electrical and optical performance of the system has been investigated.