A photo–thermal–electrical coupling degradation model for solar arrays under long-term space radiation: Model structure and a representative case demonstration

Solar arrays are a critical power source for spacecraft, and their long-term degradation is driven by both intrinsic aging and cumulative space radiation exposure. In addition, variations in array architecture and operating conditions introduce coupled optical, thermal, and electrical effects, making degradation analysis complex. In this work, a photo–thermal–electrical coupling degradation model is proposed to map system-level performance loss to parameter-level fundamental degradation, describing the degradation chain from cumulative radiation dose to radiation-induced changes in optical properties, thermal balance variation, and electrical performance degradation under long-term space environments. The model enables reconstruction of the degradation process and quantitative decomposition of attributions. A representative case study is adopted to demonstrate the workflow for a long-term space mission, including comparative evaluation of degradation behaviors and attributions among key physical parameters and commonly used coverglasses. The results indicate that cumulative radiation effects dominate long-term space degradation, and that multi-physics coupling amplifies differences in material and parameter degradation behavior. This study provides a generalized, framework-level idea for interpreting long-term solar array degradation from a physical-parameter perspective. Although the current simulation results are from a specific case, we hope that this framework can inspire future contributions to degradation attribution and reliability.