The technical and economic benefits of an energy storage system are strongly dependent on an optimal operation. Battery energy storage systems can eliminate, for example, the fluctuations caused by irregular power consumption or the intermittent nature of renewable energy sources and are thus suitable for peak shaving applications. This study has presented an analysis of the impact of power flow control strategies on the degradation of lithium-ion batteries in heterogeneous battery energy storage systems. Concurrently, a generic battery aging model based on heuristics and a focus on capacity fade has been extended. Additionally, a target indicator to analyze the impact of power flow control strategies on the degradation of batteries has been presented. Different correlations between the parameters of the aging model and the degradation have been observed. In this study, power-sharing proportional to the rated capacity leads to enhanced service life, whereas power-sharing proportional to the available power of a battery decreases the service life. However, other target indicators such as the overall efficiency of the system or the fulfillment of the power requirements cannot be neglected. Although the impact of power flow control strategies on the degradation of batteries has been identified successfully for a generic aging model, the results have to be transferred and compared to data-based aging models and real-world applications. Further studies should also consider how to manage the trade-off between all different target indicators.