Hybrid hydro-photovoltaic (PV) operation is an innovative model for improving the overall efficiency of clean energy use. However, the uncertainty of large-scale PV output substantially exacerbates the difficulty of flexible regulation in hydropower systems and creates challenges for the safe, stable, and efficient operation of hydropower units. This paper proposes a real-time dispatch method for hybrid hydro-PV based on the dynamic reserve capacity, which targets the uncertainty distribution characteristics of PV output. First, a multi-scale nested joint operation model considering short-term and real-time operation strategies is proposed to simulate the operation process of the hybrid system. Then, different reserve capacity operation strategies are formulated according to the output deviation of PV. Based on the case study conducted in the Beipan River, China, it has been proven that taking into account PV uncertainty can lead to various positive outcomes. Firstly, the total monthly water consumption can be reduced by 4.29 %, which can ensure the economic performance of the system. Secondly, the total number of monthly passes through the vibration zone can be reduced by 53 times, which is a significant reduction that can minimize the negative effects of PV power generation fluctuations on the performance of hydro units. However, it is crucial to note that this may lead to spatial loss of hydropower units, especially during extreme weather conditions.