The function of solar cell modules is to convert solar energy into electric energy, supply load work or charge battery group. The function of the controller is to protect the charge and discharge of the battery group; the battery group is used to store electric energy. The function of an inverter is to convert DC to AC. When the solar cell assembly fails to work at night or rainy days, the battery is supplied to the load. Battery can be divided into recycling and floating use. Often in the frequent charge and discharge working state, which is recycling; often in the charging state is floating charge, can make up for the battery due to self-discharge caused by capacity loss. VRLA batteries used in photovoltaic power generation systems belong to recycling mode.