Estimation of the solar radiation intensity on photovoltaic surfaces using anisotropic Models, investigation of influence of tilt angles and solar trackers: A case study for the southeastern of Türkiye

Abstract

The estimation of total solar radiation (TSR) intensity is crucial for the performance, design, and economic assessment of photovoltaic (PV) energy systems operating in different geolocations and climates. Various transposition Models can be utilized in performance calculations for PV systems in the estimation of TSR on tilted and tracked PV surfaces. Solar tracking equipment can be applied to optimize the TSR gathered by solar PV surfaces. In addition, energy gain can be considerably increased with the use of optimally tilted PV surfaces. This study aims to perform a reliable estimation of TSR for fixed and tracked PV surfaces by applying Hay-Davies, Klucher, Reindl, HDKR, and Perez anisotropic transposition Models over a specific period in Şanlıurfa Turkey. This study does not identify the best anisotropic Model, but with a relative cross-comparison, it points out the values of high variability in outputs and disagreements between different Models. The study highlights the potential of using multiple transposition Models to provide more robust estimates for the annual, seasonal, and monthly solar energy gain in desired geolocations. The annual optimal tilt angle (OPTA) for Şanlıurfa province is estimated to be 30°-31°, which is close to the latitude but below the latitude (6°-7°) of the respective geolocation. The monthly OPTA throughout the year is between 3° in July and 64° in December. It is revealed that the loss in annual TSR does not surpass 0.5% due to the 5° offset of the tilt angle from the OPTA of fixed PV surfaces. The gain in annual TSR for a fixed surface compared to a horizontal surface is estimated to be between 6.05% and 8.24%. The gain in annual TSR for a north-south oriented single-axis tracker (the axis of rotation is on the east-west plane) is estimated between 22.03% and 25.68%, whereas for a dual-axis tracker, it is estimated between 31.49% and 36.66%. It is inferred that, compared to a single-axis tracking, a dual-axis tracking can yield approximately 8.84% more energy. In light of this research, it is recommended that the solar energy potential of the Şanlıurfa can be significantly enhanced by installing tracking systems for maximal generation of solar energy. In the absence of a tracking system, the annual OPTA setting of a PV surface can be a typical strategy. On the other hand, this study reveals that some solar parameters involved in anisotropic Models significantly contribute to the quality of the estimation results. The Models presented in this study can be used to accurately estimate TSR on PV surfaces in various implementations in any place of Türkiye and around the world. © 2024 Elsevier Ltd