Author(s)

Samy A. Khalil

Solar and Space Department, National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Egypt.

The main objective of this paper is to predict the diffuse solar energy on a horizontal surface by using data of global solar energy (H) and diffuse solar energy (H_d) at different selected geographical locations in Saudi Arabia during the period time from 1980 to 2019. The low values of the root mean square error RMSE for all correlations indicated a good agreement between the measured and calculated values of H_d. The negative values of mean percentage error MPE % for all models show that for all locations, the proposed correlations slightly overestimate H_d, and the absolute values of MPE never reach 1.35%. The first, second and third order correlations between the diffuse solar fraction H_d/H and the clearness index K_t and between the diffuse transmittance H_d/H₀ and the sunshine hours have been proposed for the selected locations using the method of regression analysis. The differences between the measured and calculated values of H_d show that a first order correlation between H_d/H and K_t can be used for estimating H_d at the present locations with good accuracy. However, second order correlations between Hd/H or H_d/H₀ and S/S_o are recommended for estimating H_d at these locations. The average annual differences between measured and calculated values of diffuse solar energy H_d on horizontal at selected sites in the present research are discussed.

Diffuse Solar Radiation (DSR), Statistical Indicators, Solar Energy, Meteorological Data and Empirical Model

Khalil, S. (2022) Prediction of the Diffuse Solar Energy on Horizontal at Different Selected Locations. Energy and Power Engineering, 14, 635-651. doi: 10.4236/epe.2022.1411034.