The primary objective of this study is to design and evaluate a 100-kW rooftop solar photovoltaic (PV) system suitable for commercial applications. In response to the growing global demand for electricity, this work emphasizes the effective utilization of solar energy for sustainable power generation. A comprehensive engineering analysis is performed using PVsyst software to optimize the system configuration, with component selection based on widely available commercial options. Furthermore, a detailed MATLAB/Simulink model is developed to simulate both the direct current (DC) and alternating current (AC) sides of the system. The simulation outcomes are systematically compared with the results obtained from the PVsyst model to assess performance accuracy. A complete cost analysis is also conducted to identify the key parameters affecting the levelized cost of energy (LCOE). Overall, this study not only highlights potential avenues for future research aimed at further reducing the LCOE but also provides critical insights into the design, optimization, and implementation of commercial-scale solar PV systems.