The cascaded-H bridge (CHB) inverter is a promising topology for series-connected photovoltaic (PV)-storage (ES) system due to the high scalability and efficiency. In this study, a decentralized control scheme is proposed for each PV/ES module with only local information. For each PV module, it can independently achieve the maximum power point tracking (MPPT) and self-synchronization. For ES module, the virtual inertial control strategy is introduced to participate in the grid frequency regulation. Compared with the existing centralized modulation-based methods, the proposed method can achieve the self-synchronization and proper power regulation. Due to the communication-free feature, high flexibility and low cost are derived.