The application of building integrated photovoltaic/thermal technology (BIPV/T) in roofs is popular because of enough solar receiving area. Meanwhile, after the post-COVID-19 era, indoor air quality has become the focus. The curved characteristics of traditional Chinese building roofs incorporated the aesthetic characteristics bring new challenges for the application of BIPV/T. Thus, a novel curved CIGS+Si hybrid photovoltaic-thermal-catalysis (PV-TC) roof for electrical, thermal energy and air purification was proposed. Analysis of the proposed novel roof based on experimental and numerical modelling. Main results were: (1) According to the experimental analysis, the average thermal efficiency of the system applied in Nanjing for two days was 16.32% and 22.16%, respectively, and the average electrical efficiency was 8.7% and 8.2%, respectively. The amount of clean air generated by the removal of formaldehyde were 266.54 m3/m2 and 239.4 m3/m2, respectively. (3) The experimental data were verified by modelling, and the RMSD of the average thermal efficiency, electrical efficiency, and clean air volume generated by formaldehyde removal were 9.83%, 13.20%, 5.92%, and 4.12%, respectively. (4) Based on the model with a small error, the seasonal performance analysis of the system was conducted using this model. The average electric power in summer, winter and transition seasons was 8.7%, 10.6%, 8.9%, the average thermal efficiency was 28%, 43.6%, 29.9%, and the clean air volume was 236.9, 228.6, 220 m3/m2.