Comparative performance analysis for solar tracking systems in mid-latitude climates: Insights from a one-year experimental study

Fixed-tilt photovoltaic (PV) systems suffer from cosine losses, especially at low solar angles during morning and evening, because they cannot track the Sun’s daily and seasonal motion. This leads to optical misalignment and reduced efficiency in mid-latitude regions such as Türkiye. Although single-axis tracking systems address this issue, field-validated data on their year-long performance under real industrial conditions remain limited. This study presents a 1-year experimental comparison between fixed-tilt and single-axis tracking PV systems operating in Kocaeli, Türkiye (40°49′20.61″ N, 29°55′23.98″ E). Two identical 2.7 kWp grid-tied arrays were monitored at 5-min intervals from September 2024 to August 2025. The single-axis tracker employed an astronomical, time-based control algorithm to maintain favorable panel orientation throughout the day. The results show an annual energy gain of 28.7%, with monthly improvements reaching 38% during the summer. Winter performance was more site- and condition-dependent: under typical snow-free conditions, the realized gain was lower than in summer and strongly influenced by the direct-to-diffuse irradiance balance. In addition, a snow-shedding event highlighted an operational advantage of the tracker under specific winter conditions, but this event should not be interpreted as a universally representative winter-gain benchmark. From an economic perspective, the tracking system achieved a 12.2% lower Levelized Cost of Energy ($ 0.036/kWh) and a shorter payback period (2.25 years) than that of the fixed-tilt system (2.65 years). Therefore, these findings demonstrate the practical benefit of single-axis tracking under the current industrial rooftop conditions; however, the magnitude of the benefit depends on local climate, inverter sizing, snow behavior, and installation alignment.