Long-term measurements of global solar radiation in Osmaniye, Türkiye (2014–2023)

This paper presents the horizontal solar radiation data for Osmaniye (37◦04′N, 36◦22′E), located in Mediterranean region of Türkiye, over the period 2014–2023. Solar radiation variability, recorded at 1-min intervals, was evaluated in terms of hourly, daily, monthly, seasonal, and annual averages. Over the 10-year periods, the mean daily total and daily average global radiations received on a horizontal surface were 1,360,000 W/m2 and 371.47 W/m2, respectively. The monthly averaged daily global radiation (averaged over the 10-year period) ranged from 202.94 W/m2 in December to 496.86 W/m2 in July. The seasonal average values of solar radiations were 452.14 W/m2 in summer, 394.40 W/m2 in autumn, 353.19 W/m2 in spring, and 202.51 W/m2 in winter. The annual average clearness index ranged from 0.43 in December to 0.61 in June, with an overall mean of 0.55. In addition, the present measurements were compared with the NASA solar energy model based on a 36-year average (1987–2022). The performance between present measurement and the NASA data was evaluated using statistical metrics (R2, RMSE, MBE, and t-statistic), yielding values of 98.77%, 29.41 W/m2 20.15 W/m2, and 3.12, respectively. The measured data are generally consistent with the NASA data, with some discrepancies. Overall, the results indicate that Osmaniye Province, located on the Mediterranean coast of Türkiye, receives abundant solar radiation and therefore has strong potential for solar energy development. This paper presents the horizontal solar radiation data for Osmaniye (37◦04′N, 36◦22′E), located in Mediterranean region of Türkiye, over the period 2014–2023. Solar radiation variability, recorded at 1-min intervals, was evaluated in terms of hourly, daily, monthly, seasonal, and annual averages. Over the 10-year periods, the mean daily total and daily average global radiations received on a horizontal surface were 1,360,000 W/m2 and 371.47 W/m2, respectively. The monthly averaged daily global radiation (averaged over the 10-year period) ranged from 202.94 W/m2 in December to 496.86 W/m2 in July. The seasonal average values of solar radiations were 452.14 W/m2 in summer, 394.40 W/m2 in autumn, 353.19 W/m2 in spring, and 202.51 W/m2 in winter. The annual average clearness index ranged from 0.43 in December to 0.61 in June, with an overall mean of 0.55. In addition, the present measurements were compared with the NASA solar energy model based on a 36-year average (1987–2022). The performance between present measurement and the NASA data was evaluated using statistical metrics (R2, RMSE, MBE, and t-statistic), yielding values of 98.77%, 29.41 W/m2 20.15