The photovoltaic system combined with the building can be used as an independent power source or in a grid-connected way. When the system participates in the grid connection, it does not need a battery. However, it needs to be connected to the grid, and grid-connected power generation is a new trend in today’s photovoltaic applications. The photovoltaic modules are installed on the roof or outer wall of the building, and the terminal is connected to the public grid through the controller, which needs to supply power to the photovoltaic array and the grid in parallel to the user, which constitutes a grid-connected photovoltaic system.