Mission Profile-Oriented Control for Reliability and Lifetime of Photovoltaic Inverters

With the aim to increase the competitiveness of solar energy, the high reliability of photovoltaic (PV) inverters is demanded. In PV applications, the inverter reliability and lifetime are strongly affected by the operating condition that is referred to as the mission profile (i.e., solar irradiance and ambient temperature). Since the mission profile of PV systems is location-dependent, the inverter reliability performance and lifetime can vary considerably in practice, that is, from the reliability perspective, PV inverters with the same design metrics (e.g., component selection) may become over or underdesigned under different mission profiles. This will increase the overall system cost, e.g., initial cost for overdesigned cases and maintenance cost for underdesigned cases, which should be avoided. This article, thus, explores the possibility to adapt the control strategies of PV inverters to the corresponding mission profiles. With this, similar reliability targets (e.g., component lifetime) can be achieved even under different mission profiles. Case studies have been carried out on PV systems installed in Denmark and Arizona, where the lifetime and the energy yield are evaluated. The results reveal that the inverter reliability can be improved by selecting a proper control strategy according to the mission profile.