•A silica aerogel-based photovoltaic/thermal (PV/T) collector is proposed.•The aerogel-based PV/T collector significantly suppress radiation heat loss.•The thermal performance of the aerogel-based PV/T collector is enhanced by 46%.•The performance of aerogel-based PV/T is equivalent to that of spectrally selective PV/T with a thermal emissivity of 0.1.•The exergy efficiency of the aerogel-based PV/T collector is increased by16.2%. Photovoltaic/thermal (PV/T) collector can convert incident sunlight into electrical and heat energy simultaneously. However, compared with the solar thermal collector, the radiative heat loss of the PV/T absorber is larger since the spectrally selective PV/T absorber is difficult to design and fabricate after introducing PV cells, which leads to lower thermal efficiency. Thus, an approach that can reduce the radiative heat loss of the PV/T collector without the requirement for spectrally selective PV/T absorber is emergently needed. Here, a novel aerogel-based PV/T collector is proposed to suppress radiative heat loss and improve efficiency by introducing the silica aerogel that is highly transparent to sunlight and opaque to infrared light, as well as ultra-low effective thermal conductive into the PV/T collector. A numerical model is established to evaluate the performance of the aerogel-based PV/T collector, and the results present that the heat loss of the PV/T collector at the operating temperature of 70°C can be dramatically reduced by approximately 75% after using the silica aerogel and the thermal efficiency can also be increased by 46%. Moreover, a parametric study is conducted to investigate the influence of solar radiation, ambient temperature, and emissivity of the PV/T absorber on the performance of the aerogel-based PV/T collector. This study is devoted to exploring a new method to suppress the radiative heat loss of the PV/T collector and enhance its solar harvesting performance correspondingly, which gives a reference for the design of high-performance PV/T utilization.