Two-Stage Capacity Determination Framework for Residential Second-Life BESSs Considering Cloud Energy Storage Service

Second-life battery energy storage systems (SL-BESSs) have potential to be used as an economic and affordable energy storage solution for supporting a variety of applications, such as energy backup in residential sector. This article proposes a new capacity determination framework for SL-BESSs that are utilized in household environment. Despite the capital cost is significantly reduced, the degradation characteristics of retired batteries exhibits two-stage decline characteristics. The proposed framework first establishes the SL-BESSs model and estimates its remaining useful lifetime by identifying the "knee point " in the SL-BESSs capacity degradation curve; based on this, a two-level SL-BESS capacity determination model is formulated, which sizes the SL-BESS based on short-term home energy management under different scenarios. In particular, this article considers the dual-service modes of an SL-BESS in its capacity determination process: first, provide local energy supply to the household, and second, provide cloud energy storage service to external users. Extensive numerical simulations are conducted to validate the proposed framework.