The Performance Assessment of Hargreaves Model in Estimating Global Solar Radiation in Sokoto, Nigeria

Abstract

This paper presents, an estimation of daily global solar radiation in Sokoto (latitude and longitude)for the year 2009 using Hargreaves model. This estimation was based on latitude and daily minimum and maximum temperature in Sokoto State. The measured and estimated solar radiation data were compared forand analyzed using coefficient of residual mass (CRM), root mean squared error (RMSE), coefficient of determination (R2 and percentage error (e). The results showed that the value of CRM is 0.04, which indicates the tendency of the estimation model to under-estimate the measure solar radiation. Meanwhile, the value of RMSE was 1.63% and the value of R2 is 0.8260 which is very closed to 1, indicating that about 82.60% of the total variation is explained in the data. For the percentage error, the value was -3.16%, which indicates that the model estimation is good. The model has shown itself to be a robust and reasonably accurate method for estimating global solar radiation in Sokoto and
its environment. However, considering the uniqueness of climatological data in each month of a year, it is recommended that the model should be subjected to further validation involving months of data running over five years.