Abstract: The capacity ratio refers to the ratio of the DC-rated power input of the photovoltaic module to the AC-rated power output of the inverter. In the early stages of photovoltaic power plant construction, a 1:1 capacity ratio was commonly used for design. However, it was found in actual operation that the actual output power of the photovoltaic modules often cannot reach the rated power due to factors such as module degradation, partial shading, dust shading, and cable losses. This leads to long-term operation of the inverter at power levels below the rated power, resulting in wasted inverter capacity and affecting the economic benefits of the photovoltaic power plant. To improve the economic benefits of the photovoltaic power plant, an optimal capacity ratio scheme needs to be determined. The selection of the optimal capacity ratio can be obtained through engineering case analysis and calculations. The choice of capacity ratio may also vary under different thermal conditions. In areas with good thermal conditions, the actual output power of the photovoltaic modules is relatively high, so the capacity ratio can be appropriately increased. In areas with poor thermal conditions, the actual output power of the photovoltaic modules is relatively low, so a lower capacity ratio should be chosen. By selecting the capacity ratio reasonably, the photovoltaic power plant's electricity generation efficiency and economic benefits can be maximized. This is of great significance for promoting the development and application of photovoltaic power plants.