Movable insulation in building integrated semi-transparent photovoltaic thermal (BiSPVT) system

Abstract

The BiSPVT system involves an integration of semi-transparent photovoltaic (SPV) modules with buildings along with the provision of harvesting thermal energy. The system generates electrical and thermal energy for the building as well as provides day-lighting. However, during summer season the production of thermal energy is higher and thermal demand is lesser as compared to winter season. Also, the higher thermal energy production is unfavourable for the generation of electrical energy by SPV modules. The use of movable insulation (MI) on glazed wall can be one of the method to reduce the thermal energy generation. In this paper, a thermal model has been developed for BiSPVT system and the effect of MI on thermal performance of the system is studied. The energy balance equations are obtained for the inclined SPV modules (top), reinforced cement concrete (RCC) floor (bottom), air of room (SPV modules, floor and four brick/glazed side walls). The room temperature and SPV cell temperature are derived as a function of a) climatic parameters (solar irradiance and ambient temperature), b) design parameters and c) heat transfer coefficients by using the energy balance equations. It is found that by using MI with less or no air cavity thickness, the temperature of room has reduced by 1.93°C. However, the effect of MI on SPV cell temperature is marginal. The proposed model can be utilized to evaluate cell and room temperatures for BiSPVT system installed at different places of the world provided solar irradiance and ambient temperature of that place are known.