Impact of shortwave radiation parameterization schemes in predicting global horizontal irradiance for various climatic zones by WRF-Solar: A case study in India

A developing country like India has an ambitious target of expanding their solar energy systems in the future for generating power and process heat applications. Hence, it is integral for a developing country such as India to have a robust technique to predict the shortwave radiation in the future to effectively manage the demand and supply. Weather Research Forecasting - Solar (WRF-Solar) is employed in this study to predict the Global Horizontal Irradiance (GHI) for 14 days ahead and results are validated with the Solcast® data. Four shortwave parameterization schemes such as Dudhia, Goddard Fluid Dynamics Laboratory (GFDL), New Goddard, and Rapid Radiative Transfer Model in General Circulation Model (RRTMG) have been tested for various climatic regions in India such as warm & humid, hot & dry and composite to find out the optimal configuration that improves the accuracy of GHI prediction. It has also been performed for different seasons in a year to conduct the sensitivity analysis of the parameterization schemes. In the warm & humid climatic zone, the Dudhia scheme outperformed the other three schemes by yielding less mean Root Mean Square Error (RMSE) of 133.67 W/m², then followed by New Goddard, RRTMG and GDFL with increased mean RMSE of 6.67 %, 7.07 %, and 7.61 % respectively. In Composite climatic zone, the RRTMG scheme performed better than the other three schemes by yielding less mean RMSE of 134.58 W/m², then followed by Dudhia, New Goddard and GFDL with increased mean RMSE of 3.02 %, 4.18 %, and 12.02 % respectively. For hot and dry climatic zone, the Dudhia scheme performed better than the other three schemes by yielding less mean RMSE of 133.20 W/m², then followed by GFDL, RRTMG and New Goddard with an increased mean RMSE of 0.61 %, 4.10 %, and 5.71 % respectively. Despite the climatic conditions, all the schemes performed better in the summer season due to clear skies and below average in the monsoon season due to overcast conditions. The findings of the research are more beneficial to the stakeholders indulged in power generation using solar energy and grid operators for efficient operation in grid integration along with the management of demand and supply.