This study presents a comprehensive performance evaluation of four photovoltaic (PV) string configurations; parallel (Config A), series (Config B), one series–two parallel (1S–2P, Config C), and one parallel–two series (1P–2S, Config D); under both uniform and non-uniform irradiance conditions, considering equal- and unequal-rating strings. A single-diode PV cell model was employed to simulate current–voltage (I–V) and power–voltage (P–V) characteristics across a range of irradiance levels (100 W/m2–1000 W/m2) and temperatures (15 °C–35 °C). Results show that under uniform irradiance, Config B consistently delivers the highest maximum power (up to 3.99 kW at 1000 W/m2 and 15 °C) due to its high-voltage series topology, while Config A achieves the highest current output (70 A at 1000 W/m2) but is limited by low voltage (72 V), restricting inverter compatibility. Hybrid configurations (Configs C and D) exhibit intermediate performance, with Config C yielding 2.88 kW and Config D 2.73 kW under uniform conditions, though both demonstrate broader operational flexibility. Under non-uniform irradiance and partial shading, significant performance divergence emerges: Config A exhibits superior mismatch resilience by sustaining 66 % of short-circuit current (ISC) and 67 % of maximum power (Pmax) under full shading of one string, while Config B fails almost completely due to current bottlenecks in the series path. Hybrid topologies enhance shading tolerance, with Config D sustaining > 80 % of nominal voltage and preserving multiple maximum power points (MPPs), facilitating more robust maximum power point tracking (MPPT) in heterogeneous irradiance environments. Unequal-rating string simulations further highlight topology dependent behaviors, including staircase-like I–V curves and multi-peak P–V responses, which complicate MPPT but provide redundancy. Overall, the findings establish Config B as optimal for high, uniform irradiance conditions, while Config D emerges as the most resilient and fault-tolerant configuration under real-world non-uniform shading scenarios. These insights support the design of more efficient, adaptable PV systems capable of mitigating mismatch-induced power losses in practical installations.