THE PROJECT OBJECTIVE IS TO EXPLORE THE DEGRADATION OF CRYSTALLINE SILICON/AMORPHOUS SILICON (C-SI/A-SI:H) HETEROJUNCTION (HJ) SOLAR CELLS WITH THEORETICAL SIMULATION METHODS. OUR PRIMARY TOOL WILL BE THE SOLDEG ENGINE, DEVELOPED AT UC DAVIS. TECHNICAL SCOPE SUMMARY: (1) COMPLETION OF THE SOLDEG PLATFORM WITH INCLUDING HYDROGEN INTO THE MODEL TO CARRY OUT A COMPREHENSIVE EXPLORATION OF SI HJ CELL DEGRADATION CAUSED BY LIGHT AND TEMPERATURE-INDUCED, HYDROGEN-DRIVEN DEFECT FORMATION IN THE A-SI LAYER OF C-SI/A-SI:H HETEROJUNCTION (HJ) CELLS. (2) COMPREHENSIVE EXPLORATION OF THE EFFECTS OF CELL ARCHITECTURE. (3) ENERGY PERMITTING, ADAPT SOLDEG TO ANALYZE DEGRADATION DYNAMICS ASSOCIATED WITH SIO PASSIVATION LAYERS.