Evaluation of diffuse decomposition models

The accuracy of several models that estimate diffuse horizontal irradiance (DHI) from measured global horizontal irradiance (GHI) is evaluated. This analysis includes two aims: (1) Measured data from 17 weather stations around the world is used to compare modeled DHI to measured DHI. (2) The irradiance transposition error from 20 operating PV power plants is evaluated using combinations of commonly used diffuse decomposition and transposition models.