Estimation of Global Solar Radiation (GSR) using Seven Meteorological Parameters at Eastern Hill, Okhaldhunga, Nepal

Abstract

For developing solar energy technologies, an in-depth knowledge of the distribution of solar radiation in every geographic region is important. Using seven meteorological parameters- highest and lowest temperatures, precipitation, solar radiation, maximum and minimum humidity, and wind speed, this study used RadEst 3.0 to estimate daily GSR in Okhaldhunga, (27.31°N, 86.50°E, 1731 m) Nepal for 2021-2023. Four models; Bristow and Campbell (BC), Campbell and Donatelli (CD), Donatelli and Bellocchi (DB), and Donatelli-Campbell-Bristow-Bellocchi (DCBB) are utilized to estimate the radiation.

The models were evaluated using statistical methods such as coefficient of determination (R²), mean bias error (MBE), mean percentage error (MPE), mean bias error (MBE), and root mean square error (RMSE). Parameter fitting (PF) calibrates all four models by maximizing R² and minimizing CRM, and RMSE. In 2021, 2022, and 2023, the yearly average GSR was 14.6 ± 0.27 MJ/m²/day, 15.5 ± 0.27 MJ/m²/day and 15.4 ± 0.32 MJ/m²/day respectively. The highest GSR values were recorded in 2023 at 29.6 MJ/m²/day, with a total yearly GSR of 5618 MJ/m². CD model had the highest R² values for all three years, so it is the best model for estimating GSR in this region.