Seasonal and Distribution-Based Performance Assessment of Fixed-Tilt and Single-Axis Tracking Photovoltaic Systems Under Real Meteorological Conditions

Annual energy yield alone cannot fully characterize photovoltaic (PV) system performance, because similar yearly totals may conceal substantial operational differences under varying environmental conditions. This study presents a statistical comparison of co-located fixed-tilt and single-axis tracking PV arrays operating in an 11.9 kWp grid-connected plant in Malatya, Türkiye (38.389° N, 38.426° E). Both systems consisted of a total of thirty-six 330 W monocrystalline modules—eighteen connected in series for the single-axis tracking subsystem and eighteen for the fixed-tilt subsystem—all interfaced to a single Huawei SUN2000 inverter and operated under identical climatic exposure. Seasonal analysis showed that tracking benefit strongly depended on radiation availability. During winter, daily production was similar, and the fixed configuration occasionally generated slightly higher energy (January: 28.43 vs. 27.65 kWh; December: 23.55 vs. 20.88 kWh). In summer, tracking produced significantly higher output (113.89 vs. 77.30 kWh in July), corresponding to approximately 47% improvement, while differences in spring and autumn remained below 6%. Statistical indicators revealed strong seasonal variability. The coefficient of variation ranged from 0.61 to 0.68 in winter and decreased to 0.06 to 0.12 in summer. Percentile analysis showed similar lower production limits but higher upper production thresholds for tracking (July P90 ≈ 121 vs. 81 kWh). Tracking gain increased with irradiance and decreased under humid and rainy conditions dominated by diffuse radiation. The results indicate that tracking alters the temporal distribution and probability characteristics of PV generation rather than providing a constant annual gain. Integrating statistical metrics with meteorological parameters enables a more representative performance evaluation than annual yield alone.