Comparison of the fraction model of direct and diffuse solar radiation—Taking Beijing area as an example

In the simulation of building energy consumption and solar energy system design, hourly direct and diffuse radiation is one of the most important basic parameters.While, due to Chinese solar radiation data missing, it is difficult to obtain hourly direct and diffuse radiation data. Many domestic and foreign scholars has studied and put forward several diffuse radiation models. 2009-2011 year's measured data of total solar radiation and diffuse radiation were scleted and five typical separation models, that is Erbs model, Orglill and Hollands model,stochastic climatic model, Zhang Qingyuan model，were put to analyze and compare the measured data and the simulation data between the correlation coefficient, root mean square error and relative error. Found that Erbs model predicts diffuse radiation with the highest accuracy, followed by the Zhang Qingyuan model and Orglill and Hollands model, Clearness index Kt can be used as the main influence factor.