Circuit simulation model for photovoltaic array is very useful in simulating and evaluating the performance of power conditioning system. Among various programs, PSIM is widely used in power simulation and its physical model can handle changing output according to temperature and irradiance. However, accuracy of the model heavily depends on user-defined information. Specifically, construction of the conventional PSIM model involves calculation of tangential slope at open circuit voltage point in the I-V curve and estimation of ideality factor, both of which are obtained by trial and error and thus strongly influence the model accuracy. In this paper, a new PSIM simulation model for PV panels using online parameter tuning is presented. The proposed model utilizes only datasheet values measured under STC and excludes the necessity of the error-prone processes. Furthermore, all of the five parameters in single-diode model are successively tuned using Powell's optimization method in order to guarantee good accuracy and high speed. Comparisons with conventional model are performed using crystalline PV panel sample and the results shows that the proposed model provides more accurate and uniform performance according to EN50530 standard. (C) 2016 Elsevier Ltd. All rights reserved.