Validation of IEC 61853-2 standard (Draft): Angle of incidence effect on photovoltaic modules

The purpose of this study is to test and validate the IEC 61853-2 (draft) standard procedure for the measurement of incident angle effects on photovoltaic modules. The data obtained was processed according to IEC 61853-2 model to obtain the relative light transmission or relative optical response of all the test modules (free from the influence of diffused light component and the cosine effect). This data was compared to the data derived for the air/glass interface using various theoretical light transmission models and to the data derived specifically for the PV modules (with glass superstrate) using an empirical model developed by Sandia National Laboratories. The results show nearly identical relative light transmission plots for all the five test modules with glass superstrate irrespective of the type of PV cell technology (mono-Si, poly-Si, a-Si, CdTe or CIGS). This indicates that the reflective losses are governed almost exclusively by the air/glass interface of the PV modules. The relative light transmission plots obtained using the IEC 61853-2 model were in good agreement with the plots obtained using the theoretical air/glass interface models and the empirical model developed by Sandia National Laboratories for the glass superstrate PV modules. The standard states that “for the flat glass superstrate modules, the AOI test does not need to be performed; rather, the data of a flat glass air interface can be used. The results obtained in the current study validate this statement.