Evaluation of Light-Induced Electroluminescence in Photovoltaic Field Applications

We present a performance analysis of the new measurement method Light-Induced Electroluminescence (LIEL) in a PV system. The LIEL method is applied to photovoltaic (PV) modules consisting of two PV module halves which are internally connected in parallel. Today’s main stream half-cell modules are constructed this way. To measure the electroluminescence of one half of the module, the other half is illuminated by an LED array. Our LIEL prototype system is a hood-based setup. It is equipped on one half with a LED array that is separated by a wall from the other half. This other half is observed by an InGaAs camera. We measure the impact of a LIEL hood misalignment to the electroluminescence intensity, the influence of the PV generator working point to the electroluminescence intensity and determine the measurement speed under realistic conditions. We show that the experimentally realized LIEL hood alignment to the PV modules is in 97.7% of the cases sufficient for acquiring high quality EL images. The LIEL system work with a switched off and on inverter. Under inverter on working condition the luminescence intensity is a function of the intensity of the sun. The effect of hood alignment and sun intensity on the luminescence intensity is successfully reproduced by an analogue electronic circuit simulation using LT Spice. The maximum measuring speed of a full module is in this study 12 s including the time for movement and alignment of the measurement hood from PV module to PV module