First, we analyze quality of solar irradiance data which we collected through long-term meteorological observation in Bangkok. Second, the collected solar irradiance data are compared with EPW format data around Bangkok, it is shown that there are differences in the trend of solar irradiance depending on the data point. Next, the applicability of splitting models of solar irradiance is verified. It is shown that the estimation errors of the Perez, Erbs, and Zhang models are affected by the sun altitude. Moreover, it is revealed that the estimation accuracy of Perez model tends to be lower during the rainy season.
