Impact of Power Converters and Battery Lifetime on Economic Profitability of Residential Photovoltaic Systems

The installations of the residential photovoltaic (PV) systems with integrated battery energy storage are strongly dependent on their economic profitability. The Net Present Value (NPV), which is a metric to evaluate the cost-effectiveness of PV-battery systems, can be strongly influenced by the replacement cost. Thus, the lifetime of the reliability-critical components such as power converters and battery plays an important role and needs to be considered during the economic evaluation. In this paper, an impact of power converters and battery lifetime on the economic profitability of the PV-battery system for different installation sites is analyzed. A comprehensive model, consisting of system performance, lifetime, and economic profitability aspects as well as their interconnections is developed in this paper. A case study reveals that the NPV can be significantly over-estimated if the power converters and battery need to be replaced several times during the entire lifespan of the PV-battery system. Hence, the lifetime analysis should be included in the economic assessment and reflected with a more realistic component replacement cost during the planning stage of the residential PV-battery projects.