Shunt resistance analysis and capacitive degradation in a vertical solar cell under extreme conditions

In this study, we analyze the behavior of the shunt resistance and its impact on the capacitive degradation of a vertical silicon solar cell subjected to extreme operating conditions. The investigated device, an n⁺/p/p⁺ vertical-junction photodiode, is modeled under steady-state conditions with polychromatic illumination, taking into account both thermal and optical effects on the key electrical parameters.
The theoretical approach relies on the minority carrier continuity equation in the base, extended with a resistive loss term associated with the shunt resistance, whose value decreases significantly with increasing temperature and light intensity. Simulations show that a low shunt resistance (< 50 Ω·cm²) induces a substantial degradation of the diffusion capacitance, thereby hindering the efficient collection of photogenerated charges.
The results highlight a strong coupling between resistive losses and capacitive behavior, leading to a noticeable performance drop in environments with high temperature (> 70 °C) or under intense illumination. Critical thresholds are identified to ensure the capacitive stability of the cell, paving the way for thermal and structural optimization strategies for reliable operation under severe conditions [2],[3].