Experimental data from a 17.5% efficient perovskite solar cell has been used to develop a self-consistent device model using Solar Cell Capacitance Simulator (SCAPS). Electronic properties of the individual layers, such as doping density of compact TiO2 (c-TiO2), doping and defect density of perovskite, etc. are extracted from experimental data. The only fitting parameters in the model are the defect densities at spiro-MeOTAD/perovskite interface (IL-1) and perovskite/TiO2 interface (IL-2). The simulated current-voltage (J-V) characteristics and Mott-Schottky plot results match extremely well with the experimentally measured plots, validating the device model. The model was further used to extract insights into the loss mechanism of the high-efficiency perovskite solar cells. Simulations revealed that defect density at IL-1 interface has strong impact on the open-circuit voltage (Voc), while defect density in the perovskite and IL2 interface has a major impact on short-circuit current density (Jsc).