The Cube 261-Y integrated photovoltaic - energy storage system adopts an integrated multi-functional design. It supports photovoltaic access and seamless grid-connected and off-grid switching, covering all scenarios of photovoltaics, energy storage, and diesel generators. Equipped with an intelligent and efficient Static Transfer Switch (STS), the grid-connected and off-grid switching time is less than 20ms to ensure stable power supply. It provides users with functions such as peak-shaving and valley-filling, demand response for grid dispatching, and power backup services, improving the off-grid power self-sufficiency rate.