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.