In addition to creating energy and saving energy, a very important part of smart grid technology is energy storage. Due to the intermittency and volatility of renewable energy generation, it is difficult to match with the "continuity" and "stability" of power supply, so energy storage equipment as a regulatory role has become an indispensable part of the system. In other words, in order to make up for and absorb the power generation gap on the sun and wind, the energy storage equipment needs to have the corresponding backload capacity and instantaneous power supply capacity to store electrical energy and receive the buffer when the instantaneous power is generated.

More importantly, energy storage devices can stabilize the voltage and improve the poor quality of electricity generated by renewable energy connected to the grid. In general, renewable energy power generation systems can be divided into grid-connected and independent, when grid-connected renewable energy generation accounts for more than 10% of the total power generation, its system reliability and impact will threaten the public grid, so it must be set up energy storage equipment. Ordinary households or small grid-connected systems do not need. The independent power supply system is mostly set in distant areas or where the power grid is difficult to popularize, as an important backup system, energy storage equipment is indispensable.

More broadly, from the perspective of application, in industrial use, in addition to being an emergency backup power source system, the key function of the energy storage system is to strive for sufficient buffer time for other machines and equipment, industrial computers, etc., to reduce operating losses and data damage caused by sudden power outages. For example, a data center with a large number of DC servers is a typical application example. For people's livelihood purposes, most of them are integrated with renewable energy power generation systems and residential buildings. Especially after the Fukushima nuclear disaster in Japan, there is a trend of gradually spreading from large-scale energy storage systems to household energy storage devices. A small and decentralized energy architecture to make energy supply more independent and balance off-peak power or idle power to support high power consumption areas.

Looking at the energy storage technologies currently in development, there are various types of batteries for electrochemical energy storage, electrical energy storage supercapacitors, kinetic energy storage flywheel systems, and potential energy storage pumped hydro energy storage. compressed air energy storage, etc. However, in terms of cost and technological maturity, the battery has become the most commercialized solution.