Prediction and Comparison of Daily Global Solar Radiation using Meteorological data at Lalibela, North Wollo, Ethiopia.

Abstract

The air temperature and sunshine duration data were obtained from Kombolcha Meteorological Agency to predict daily global solar radiation at Lalibela, Ethiopia. The mean daily clearness index and mean daily global solar radiation was calculated based on sunshine and air temperature model for the study sites. The validation of the models for predicting mean daily global solar radiation was done using statistical tests such as: MBE, RMSE, MPE and R. The result of these statistical tests for temperature based model: (MBE_tem=. -0.50, RMSE_tem=0.67, MPE_tem=-2.9 and R_tem=0.06) and for sunshine based model: (MBE_sun=. 0.08, RMSE_sun= 0.49, MPE_sun= 1.50 and R_sun= 0.05). From overall, it was concluded that the better value of the mean daily global solar radiation was observed with sunshine based model (Angstrom-Prescott) than the temperature based model (Hargreaves and Semani) in almost all of the days of the study and be applied to locations with comparable weather condition with Lalibela sites.

The maximum average daily global solar radiation that predicted from sunshine hours was 5.86 KWh/m² and the maximum average daily global solar radiation that predicted from air temperature was 5.28 KWh/m² over a period of 3 years (2014-2016).

The result of this study was between the minimum and maximum value of [14] and therefore, the region has high potential for solar energy application.