The optimal capacity of a battery energy storage system (BESS) is significant to the economy of energy systems and photovoltaic (PV) self-consumption. In this study, considering the long-term battery degradation, a mixed-integer nonlinear programming (MINLP) model was proposed for the PV-battery systems which aim to minimize the life cycle cost (LCC) and was solved by a novel two-layer optimization method. This study compared optimal battery capacities, LCCs, and self-consumption ratios (SCR) under two types of tariffs with and without considering battery degradation. The effects of feed-in tariffs, feed-in limits and PV degradation on the optimization results are discussed. The results showed that the battery degradation could cause an increase in operation cost. The cases considering battery degradation have larger battery capacity and more life cycle cost than the cases without considering battery degradation. Compared with the feed-in tariff profile of flat rate, the cases with feed-in tariff profile of time-of-use have smaller optimal battery capacity, higher SCR, and lower LCC. The feed-in tariff, feed-in limit and PV degradation have an important impact on optimal battery capacity and total life cycle cost. This study provides an optimization method and theoretical analysis for the capacity and operation optimization of PV-battery systems.

电池储能系统 (BESS) 的最佳容量对能源系统和光伏 (PV) 自耗的经济性具有重要意义。在这项研究中，考虑到长期电池退化，提出了一种混合整数非线性规划（MINLP）模型用于光伏电池系统，旨在最小化生命周期成本（LCC），并通过一种新型的两层优化方法。本研究在考虑和不考虑电池退化的两种关税下比较了最佳电池容量、LCC 和自耗率 (SCR)。讨论了上网电价、上网限制和光伏退化对优化结果的影响。结果表明，电池退化会导致运行成本的增加。考虑电池退化的情况比不考虑电池退化的情况具有更大的电池容量和更多的生命周期成本。与平价上网电价模式相比，分时上网电价模式的电池最佳容量更小，SCR更高，LCC更低。上网电价、上网限制和光伏退化对最佳电池容量和总生命周期成本有重要影响。该研究为光伏电池系统的容量和运行优化提供了一种优化方法和理论分析。馈入限制和光伏退化对最佳电池容量和总生命周期成本有重要影响。该研究为光伏电池系统的容量和运行优化提供了一种优化方法和理论分析。馈入限制和光伏退化对最佳电池容量和总生命周期成本有重要影响。该研究为光伏电池系统的容量和运行优化提供了一种优化方法和理论分析。