Thermal and Lifetime Analysis of Inverters and Optimisers in Building-Integrated Photovoltaic Applications: A Study on Placement and Environmental Sensitivity

Abstract

This paper presents a comprehensive analysis of how the placement of key power electronic components within building-integrated photovoltaic (BIPV) systems influences their thermal behavior and long-term reliability, focusing on lifetime estimations of the IGBT switches in both inverters and optimisers. A building physics model including the BIPV system was incorporated and integrated within the power electronics device models. This joint model assesses the impact of surrounding conditions on power inverters and optimisers and explores various practical placement scenarios. A sensitivity analysis was conducted under different environmental conditions to evaluate the effects of airflow rates, BIPV ventilation cavity opening dimensions, and radiation-convection ratios on the system's thermal behavior. Results indicate that proper placement strategies with sufficient airflow can significantly enhance cooling, reduce thermal stress, and improve the lifetime of the IGBT. This is particularly evident in the case of the inverter, where the DC IGBT (IGBT in the DC-DC converter stage) located in an isolated ceiling has an increased lifetime consumption of 10.9 % compared to an inverter placed in a utility room. This work provides valuable insights for the design and optimisation of BIPV systems in real-world applications, aiming to improve the operational lifespan of the systems.