Photovoltaic module characteristic influence on reliability of micro-inverters

Due to an integrated system structure between the Photovoltaic (PV) module and inverter, the characteristic of PV module can strongly influence the operating condition and loading of micro-inverters. The commercially available PV module has a certain variation in terms of power rating and voltage at the Maximum Power Point (MPP). Accordingly, the PV micro-inverter loading conditions, and thereby the reliability, will inevitably be affected by those variations. In this paper, the impact of PV module characteristic on the reliability of micro-inverters is investigated. Six commercial PV modules are used to demonstrate the variation in the PV module characteristic in real-field operation, and the mission profile of the installation site in Arizona is used as a case study. The evaluation results indicate that the voltage at the MPP of the PV module has a strong influence on the thermal loading and reliability of the micro-inverter. Employing a PV module with high voltage at the MPP can effectively reduce the loading of the micro-inverter, since the inverter efficiency is maintained at a high level during the operation. In that case, a high-reliable operation of the micro-inverters can be achieved.