Energy storage systems can effectively improve the inertia of PV systems and achieve power smoothing of PV power generation due to their fast and flexible power regulation capability. This study proposes a BESS charging and discharging control method with limited PV fluctuation smoothing for the capacity optimization of energy storage in high permeability PV grids. This method can reduce the number of times the BESS is charged and discharged and improve its service life while smoothing out large fluctuations in PV power output.