Estimation of the Global Horizontal Solar Radiation in Iraq

The aim of this work is to obtain an empirical simple equation to estimate the global horizontal solar radiation (GHSR) as a function of the latitude only. Therefore three empirical models proposed to estimate the GHSR using 17 different locations across Iraq. The models formulated as: Quadratic, 2nd Fourier and 2nd Gaussian expression. The simply input feature beside a fine predictive ability for modeling and a good agreement showed by comparison with observed values for 21 years with accuracy15%. The quadratic model is considered as more suitable and simple than either Fourier or Gaussian model. It shows that the annual mean predicted error for Amarah is between 3.99%-13.35%, for Rutbah between 2.22%-8.44% and for Biaji between 3.94%-12.11%. The forecasting for the period 2010-2013 shows that values of AMPE% for Amarah is between 4.10%-6.95%, for Rutbah is between 7.64%-10.42% and for Biaji is between 5.39%-7.35%.The climatic mean percentage error (CMPE) is 9.37%, 5.21% and 7.38% for Amarah, Rutbah and Biaji respectively. Keywords— empirical models, global horizontal solar radiation, Iraq, latitude dependence.