Developments of solar energy application are widely promoted currently over the world. Most researchers focus on the production improvement and power generation efficiency raise of photovoltaic (PV) cells. However, main issues of quality control or inspection of PV system maintenance are essential to minimize the outage period and maximize the lifetime output of PV system. In order to conform to the demand, Time domain reflectometry (TDR) technology would be feasible among reviewed methods for PV inspection. Therefore, this study proposes the modified TDR signal processing methodology and the calibration procedure development for PV inspection. Furthermore, the study would cooperate with the virtual instrument software to establish the relative PV system inspection program. These developments would be included to the suggested standard operation procedure (SOP), and increase the PV system inspection accuracy and efficiency using TDR practically.