PV Micro Inverter Reliability Prediction Based on RIAC

This paper discusses the reliability prediction of a 250 W photovoltaic micro inverter. Using the bill of materials the reliabilities of the main, gate drive, power supply, current and voltage sensing and microprocessor circuits were investigated, and the failure rate calculated. To take the temperature into account, the hourly temperature has been recorded for four years to generate a histogram temperature versus percentage time spent at each temperature. The failure rate of the component was calculated at each inverter operating temperature, and multiplied by the percentage occurrence of this operating temperature to obtain a weighted failure rate. A similar procedure was used to calculate the failure rate of a 240 W photovoltaic micro inverter main circuit to compare the failure rate of the components for the two photovoltaic micro inverter main circuits. All calculations are based on Reliability Information Analysis Center (RIAC) method as one of the most recent reliability methods and show the influence of each inverter component on PV micro inverter reliability.