Innovative PV Micro-Inverter Topology Eliminates Electrolytic Capacitors for Longer Lifetime

An extremely reliable micro-inverter is critical to the success of the AC PV building block and the AC PV module concepts. [1,2,3,4]. An innovative inverter design has been developed and prototyped in order to address some of the most critical issues associated with extending the mean time between failure (MTBF) and the total lifetime of the micro-inverter when it is integrated onto a PV module. The innovative micro-inverter addressed in this paper uses a unique proprietary circuit topology to reduce the numbers and sizes of capacitors, is currently rated at 150 W, and has been shown to be thermally robust and feasible. Additionally, the smaller capacitors used in the design use advanced technology exhibiting much longer lifetime (30-year) in the anticipated thermal environment. The unconventional micro-inverter design considerations, layout, early findings from modeling and evaluation results are presented. Preliminary findings for proposed redesign to increase the rating to 300 W are presented. An initial assessment of a reliability requirement study for micro-inverters is also discussed