Abstract: Aiming at the hot spot failure caused by local shading of photovoltaic panels,which makes photovoltaic panels unable to work normally,a photovoltaic panel fault detection circuit composed of optoelectronic isolation and RC oscillator is proposed. Firstly,a photovoltaic panel fault detection circuit composed of photoelectric isolation and RC oscillator is designed,and the current signal of photovoltaic panel is converted into a resistance signal by photoelectric isolation to control the RC oscillation frequency. Then the circuit topology is designed,the module frequency parameters are detected in turn,the relative deviation of corresponding photovoltaic panels is calculated,and the existence of hot spot faults in photovoltaic panels is judged. Finally,the physical circuit and Proteus simulation experiment are built,and the results show that the output frequency of faulty photovoltaic panel and its relative deviation are low,which can effectively detect the hot spot fault of photovoltaic panel.