The lithium iron phosphate batteries with high performance and long service life are used in the energy storage module. Meanwhile, the modular structure design is adopted. Each energy storage module is internally integrated with the intelligent BMS system, which can be easily expanded and can be combined into 20Kwh battery pack at most.The battery storage can be combined with inverter to form an off-grid photovoltaic system, which can solve the problem of electricity consumption in areas without electricity.