How is battery degradation modeled for grid storage applications?

Battery degradation modeling considers: calendar aging (time and temperature dependent, occurs even at rest), cycle aging (function of depth of discharge, charge rate, temperature), and specific stress factors (high/low SOC, extreme temperatures). Models range from empirical (capacity fade curves from testing) to electrochemical (model internal processes). Key metrics: capacity fade (Ah loss), resistance increase (power fade). Grid applications require: projecting remaining useful life, optimizing dispatch to manage degradation, warranty compliance verification, and augmentation planning (adding capacity to maintain requirements). Degradation varies significantly with operating profile.