In the present study, the thermal performance has been evaluated for optimally tilted semi-transparent BIPV panel, which is fixed as a roof system on a two-storied single room sample building. In the mathematical model, the periodic nature of insolation, ambient air temperature, BIPV cell temperature, intermittent slab temperature, and room temperature have been considered while solving energy equilibrium differential equations. The insolation values used in the model are computed by using periodic HDKR (Hay, Davies, Klucher and Reindl) model, which is based on anisotropic sky concept. The influencing parameters i.e., air changes in both rooms of the two-storied BIPV thermal system, packing factor of the BIPV panel and the thickness of slab between rooms are considered for finding the thermal performance. It is observed that the most critical day of the year i.e., on 15th May, the upper storey and lower storey of the proposed BIPV system attains the highest room temperature of 47.3 degrees C and 42.6 degrees C, respectively. The air changes in the rooms reduce the above peak temperature for making it more comfortable. The BIPV cell temperature also reaches up to 65 degrees C resulting reduction of the efficiency by 18% than that of standard test condition. (C) 2020 Elsevier Ltd. All rights reserved.