Abstract This study numerically investigates the optimization of P3HT/Si hybrid solar cells for maximum efficiency via numerical simulation using SCAPS ID. Our analysis reveals that the P3HT layer thickness and Si donor density are crucial parameters, with optimal values of 25 nm and 1E+17 cm-3, respectively. Beyond these values, efficiency decreases due to reduced hole mobility, increased recombination, and enhanced absorption loss. Additionally, minimizing defect density in Si is essential for achieving high efficiency. By optimizing these parameters, we achieved a maximum efficiency of ~24%, demonstrating the potential for high-performance hybrid solar cells. This work highlights the importance of numerical analysis in designing efficient hybrid solar cells, paving the way for low-cost, high-performance devices via spin coating, a significant breakthrough in solar energy harvesting.