The overall performance of a novel semi-transparent photovoltaic window with passive radiative cooling coating – A comparative study

Semi-transparent photovoltaic (STPV) glazing is a promising building integrated photovoltaic (BIPV) technology for converting traditional windows into on-site energy-producing building components. Besides electricity generation, there is also an urgent demand to enhance the thermal management of STPV glazing. Passive radioactive cooling paint is an emerging nanomaterials technology that shows great potential to reduce the painted surface temperature. Aiming to further promote the PV window's energy efficiency, this study designed and investigated a novel coated semi-transparent photovoltaic (CSTPV) glazing supplemented with highly transparent passive radiative cooling coating. In addition, the STPV/CSTPV's impacts on indoor visual environments were investigated, especially on the rarely studied aspect of interior colour rendering performance. This paper employs a combination of numerical simulation and experimental measurements to comprehensively assess these innovative glass systems in terms of electricity generation, thermal performance, daylighting efficiency, and the impact of color on the indoor environment. The results indicate that the CSTPV windows can significantly reduce the heat gain rate by about 15 % and achieve excellent electricity generation, with an annual output approximately 3 % higher than that of STPV windows. Despite the radiative cooling coating, CSTPV glazing maintains a level of daylight illumination comparable to that of STPV glazing, with glare levels remaining within acceptable limits. Furthermore, the study emphasizes the effects of CSTPV and STPV on the indoor Color Rendering Index (CRI) and Correlated Color Temperature (CCT) performance. All samples measured have CCT values within the range of neutral light, and CRI values exceeding 96, demonstrating satisfactory high-quality indoor lighting conditions. This research shows that CSTPV and STPV glass technologies not only significantly enhance the energy efficiency of buildings but also provide a scientific foundation for sustainable development in architectural design.