Improved accuracy over established temperature-based models of estimating monthly average daily global solar irradiation by using ambient hourly temperature only

Abstract

A recently developed temperature-based model for predicting monthly average hourly global horizontal irradiation has been used to estimate monthly average daily global horizontal irradiation. In addition, a modified form of the Hargreaves-Samani model was implemented. Both models were evaluated alongside five existing temperature-based models due to Hargreaves and Samani, Allen, Bristow and Campbell, Goodin et al., and Hassan et al. for performance and applicability in Trinidad. Calibration and validation of the models were done using datasets of global horizontal irradiation and temperature from 2001–2005 and 2006–2010, respectively. The newly developed temperature-based model performed better than all other models. For an average year, yearly periods, and average and yearly periods collectively, the newly developed temperature-based model yielded root mean square errors of 0.51, 0.86, and 0.68 MJ m−2 day−1, respectively, between the calculated and measured monthly average daily global horizontal irradiation. Similarly, the modified Hargreaves-Samani model was the next best performer with root mean square errors of 0.91, 1.31, and 1.11 MJ m−2 day−1, respectively.