Long-term inverter operation demonstration at Sandia National Laboratories

The performance of a utility interactive photovoltaic (PV) system relies on several key components within the system. The effects of long term operation on utility interactive inverter performance are the topic of this paper. Years of anecdotal evidence indicates that the PV module typically has a 1% per year degradation in performance; this is accepted by industry for how modules are typically rated and warranted. The inverter on the other hand has not undergone such scrutiny to investigate the effects that years of operation may have on the performance of an inverter. The effects of long-term field operation on utility interconnected PV inverters are the focus of the long term inverter evaluation test bed that is dedicated for years of operation. The outcome of this analysis will be factored into the inverter performance model. Sandia National Laboratories Distributed Energy Technology Laboratory (DETL) has recently completed the first re-characterization phase on inverters operating for two years. This paper reports on the effects of long term inverter operation on four residential inverters.