Reliability consideration of low-power-grid-tied inverter for photovoltaic application

In recent years PV modules have been improved evidently. An excellent reliability has been validated corresponding to Mean Time between Failure (MTBF) between 500 and 6000 years respectively in commercial utility power systems. Manufactures can provide performance guarantees for PV modules at least for 20 years. If an average inverter lifetime of 5 years is assumed, it is evident that the overall reliability of PV systems [PVSs] with integrated inverter is determined chiefly by the inverter itself. It must be considered that the module integration of the inverter results in harsh environment especially like high temperature stress. This paper presents a single stage integrated inverter applied in low power situation, analyzes the failure rate, contrasts three different approaches of reliability prediction for electronic equipment and simulates the thermal behavior of the integration PVSs. As a result, a high reliability PV inverter has been achieved successfully by employing film capacitors and semiconductor power modules instead of conventional electrolytic capacitor and discrete power switches. Moreover, an optimum housing design in terms of thermal management improves the inverter reliability.