For the purpose of control and monitoring of a Photovoltaic (PV) system its current-voltage (I-V) characteristic curve is traced. Usually such a test involves the interruption of the normal operation of the PV systems. In this paper a method for tracing the I-V curve from on-site measurements is proposed. During the measurement of the characteristic curve the normal operation of the PV system is not interrupted. The subjects of tracing the characteristic curve and Maximum Power Point Tracking (MPPT) of PV arrays are generally dealt with separately but the proposed method performs the measurement of the characteristic curve quickly and so it can also be utilized for MPPT purposes. Simulations and experiments have been conducted to confirm the operation of the proposed method. (C) 2016 Elsevier Ltd. All rights reserved.