General models for estimating daily diffuse solar radiation in China: Diffuse fraction and diffuse coefficient models.

Abstract Empirical models proposed to estimate the daily diffuse solar radiation (H d) in different areas worldwide, are ordinarily site-dependent. Thus, a timely scientific question would be if an application of such an empirical model to other stations can occur, without any H d records. To estimate the daily H d of these stations in different areas without H d , it is critical to establish the general models of the estimation of regional daily H d. Therefore, daily meteorological data, including daily H d , daily global solar radiation H d , daily sunshine duration, daily average temperature and daily average relative humidity, were collected and analyzed in this paper. Considering different data conditions of stations (with and without H , five diffuse fraction and three diffuse coefficient models were proposed and calibrated. Through the analysis of statistical indicators, the most efficient diffuse fraction and diffuse coefficient models were identified. According to the climatic classification, the meteorological data were collected and gathered. Then, the gathered data were used to determine the generalized constants of general models based on the best models. The results demonstrated that the general models proposed in this paper presented satisfactory accuracies and could represent the general models for the daily H d estimation of stations without H d records in China. [ABSTRACT FROM AUTHOR]