Abstract: Photovoltaic (PV) modules experience performance degradation due to multiple environmental stresses during long-term outdoor operation. Accurately establishing a degradation mechanism model and optimizing operation and maintenance (O&M) strategies are crucial for enhancing economic benefits. By analyzing the physical mechanism of module power degradation, a multi-stage degradation dynamics model based on the Arrhenius equation and Weibull distribution was established. This model quantifies the coupled influence of environmental factors on module lifespan. An O&M strategy optimization model for minimizing total lifecycle costs was constructed, and an improved genetic algorithm was used to solve for the optimal maintenance plan. Simulation verification indicates that optimizing O&M strategies can extend the average lifespan of modules to 27.8 years and reduce total lifecycle O&M costs by 23.4%.