In order to elucidate the mechanism of thermal runaway of the solar cell, we created a simulation model consisting of positive feedback due to the temperature characteristics of the shunt spot and negative feedback due to the thermal resistance of the spot, and calculated the temperature distribution of the solar cell. In this paper, we report the simulation results of the shrinkage rate of the shunt spot diameter, the change of the shrinkage rate due to the design change of the solar cell, and the change of the shrinkage rate due to the addition of electrode resistance. Furthermore, we propose design formulas for elucidating the spot diameter stop mechanism.
