We study for long-term performance of amorphous silicon solar cells under light exposure. The performance is predicted with a kinetic model in which the carrier lifetimes are determined by the defect density. In particular, the kinetic model is described by the stretched-exponential relaxation of defects to reach equilibrium. In this report, we simulate the light-induced degradation of the amorphous silicon solar cells with the kinetic model and AMPS-1D computer program. And data measured for outdoor performances of various solar cells are compared with the simulated results. This study focuses on examining the light-induced degradation for the following amorphous silicon pin solar cells: thickness${approx}$300 nm, built-in potential${approx}$1.05 V, defect density (at t=0)${approx}5{ imes}10^{15}cm^{-3}$, short-circuit current density (at t=0)${approx}15.8mA/cm^2$, fill factor (at t=0)${approx}0.691$, open-circuit voltage (at t=0)${approx}0.865V$, conversion efficiency (at t=0)${approx}9.50%$.