Abstract:
Solar irradiance model can reduce the uncertainty of solar power plant output caused by solar
irradiance intermittency. In this study, multiple linear regression (MLR) and artificial neural
network (ANN) methods were used to predict the direct normal irradiance (DNI) over Bahir Dar.
The ANN was developed using the Bayesian learning algorithm. To do this we have utilized
hourly meteorological satellite data from National Solar Radiation Data Base (NSRDB) from
January 1, 2017 to December 31, 2019. The model was trained using 70% of the data and 30% for
testing the accuracy of its prediction. Hour, temperature, relative humidity, solar zenith angle, wind
direction, wind speed, diffuse horizontal irradiance and global horizontal irradiance are used as the
input variables for models to get DNI. Both MLR and ANN models’ prediction accuracy was
assessed statistically using average root-mean-squared error (RMSE), mean absolute error (MAE)
and the square of Pearson correlation coefficient (R2
). The MLR model showed poor
generalization abilities with the squared correlation coefficient of R2 = 0.9254 compared to ANN
with squared correlation coefficient of R
2~1. In general, the average RMSE and MAE between
modeled and observed DNI for ANN model is generally lower compared to multiple regression
model. The statistical analysis suggests the potential of ANN over MLR model for DNI predicting
using the meteorological data as the main driver of its variability.