Estimation and Analysis of Global Solar Radiation in Bangkok, Thailand

Abstract

Estimations of direct, diffuse and global solar radiation were analytically and numerically achieved via Paltridge and Sabbage methods, yielding the profiles of solar irradiance for Bangkok, in March and April 2009. Both models have different advantages and complications; i.e., eight parameters of cloud and astronomical data were required for running PM and so 15 meteorological parameters were for SM. Daily and monthly solar radiations for 61 consecutive days, representing summertime, were calculated and profiled, together with the statistical tests by RMSE and MABE. Results show that PM was able to provide reasonable predictions of diffuse solar radiation with the RMSE and MABE in a range of 0.18–0.69 and 0.18–0.64 in March, equally for both values around 0.17–0.68 in April. These also showed good agreement with the data from pyranometer (MS 802) measurement. Daily global solar radiation determined by SM indicated similar trend with the actual data. Iest values were in a range of 21.46–29.27 MJ/m2/day with the RMSE and MABE = 6.61 in March and 21.63–29.43 MJ/m2/day with RMSE and MABE = 5.78, respectively. Moreover, the AODs were achieved at 0.05–0.17 and 0.07–0.75 for the PM and SM, respectively. In summary, the estimations of solar radiation based on computational modeling and empirical equations could practically provide reliable and instantaneous values of solar irradiation components for any location without any constraint of instrumentation or weather condition, meriting the further investigation and challenge in future research.