Reliability of candidate photovoltaic module-integrated-inverter topologies

This paper examines the reliability of candidate topologies for a PV module-integrated inverter (MII). A new approach to calculate the mean time between failure (MTBF) using the MIL-HDBK-217 stress factor method is proposed. The new approach takes in consideration the usage model of the inverter, the statistical distribution of expected operating temperature and power processed, rather than a single (typically worst-case) operating point. The technique is applied to the systematic reliability comparative study for six different inverter topologies. This study shows the impact of each component on the inverter's reliability, in particular, the power decoupling capacitors.