The work concerns experimental and theoretical studies of building integrated semitransparent photovoltaic/thermal (BiSPVT) system. The analytical expressions for temperature dependent electrical efficiencies of the system have been established. It concerns a roof integrated semitransparent mono crystalline silicon (c-Si) PV with two options: (i) with air duct or (ii) without air duct. An experiment has been performed on a specially designed proto-type c-Si BiSPVT set up built in Indian Institute of Technology, New Delhi, India. Theoretically calculated results using derived expressions have been validated with experimentally measured thermal and electrical parameters for both cases. A fair agreement between theoretically calculated and experimentally measured values is observed. The characteristic curves, energy and exergy analysis have also been performed particularly under cold climatic conditions of Srinagar, India. Further, to maximize the electrical and thermal efficiencies, BiSPVT system has been optimized for various design parameters as cross sectional area of air duct, duct height, fluid flow velocity, packing factor and number of air change. Without air duct, the efficiency (eta(m),) and the average room temperature (T-r) are found to be 12% and 25 degrees C respectively, whereas with air duct the BiSPVT systems inflicted the efficiency (eta(m)) and temperature (T-r) to be 13.11% and 10.1 degrees C respectively. (C) 2016 Elsevier Ltd. All rights reserved.