The power distribution networks (PDN) are spread in different street and Alley. Furthermore, nowadays, the DG is used in PDN, especially photovoltaic (PV). Therefore, fault location in these PDNs is complex. In this paper, an improved impedance based method has been proposed for fault location in power distribution network with presence of photovoltaic distributed generation resources. According that the PV has an uncertain behavior in different conditions, the proposed method is designed to be robust against PV behavior and upstream feeder changes. In the suggested method, detail equations are derived to prove a new quadratic equation forlocating fault in PDNs using recorded voltage and current at the beginning of feeder and DG terminals. According to this proved equation is depended on to just voltage and currents of source or substation terminals, consequently dynamic modeling of PV and substation is not important in the proposed method. Within this method, the pi line model is used for improving the accuracy of the suggested method. To evaluate the accuracy of the proposed method, the modified 11 node test Feeder is simulated in the MATLAB software and sensitivity of the suggested method was investigated against the different fault distances fault types, fault resistances and fault inception angles. Furthermore, the proposed method is investigated and tested on the real test feeder in power system simulator of power system and protection Lab. in Persian Gulf University. The results indicate the high accuracy of the algorithm. (C) 2018 Elsevier Ltd. All rights reserved.