Abstarct: For this protection problem, the technique is baxsed on measurements of photovoltaic parameters such as voltage, current, radiation intensity, temperature, etc. At present, one of the problems of the fault detection algorithm in the solar cell panel inability They are in the detection of the exact location of the defect event in the system. In this research, defect detection and identification in photovoltaic systems has been investigated using the H2 / H∞ method. Real systems always include uncertainties or uncertainties that these uncertainties can be due to uncertainty in the presence of disturbances. The system, however, has the necessary flexibility to function properly for uncertainties. In this research, a Robust method using H2 / H∞ has been used to design an fault detection system. To demonstrate the efficiency of this method, the system outputs the difference between the output of the model and the remaining signal, using the simulation to ensure that the system continues to work. The main purpose is to provide a Fault Detection and Isolution System (FDI) using H2 / H∞ Robust method in such a way as to maximize the effect of the fault on the model to detect the defect by the residual signal and the system is Robust to Dicturbance so that it can carry on. A Robust method using H2 / H∞ is one of the methods that ensures system performance in the presence of dicturbances and various uncertainties.