The important uses of energy storage batteries are as follows:

Since the working characteristics of solar cells are affected by changes in solar illumination (irradiation) intensity, temperature and other factors, it is often difficult for the load to operate in the best working condition when the solar cell module is directly connected to the load, and the system efficiency is very low. However, when the battery is used as an energy storage battery, the working voltage of the solar cell will be used as a clamp. The solar cell will be converted to charge the energy storage battery, and the energy storage battery will supply power to the load smoothly (especially the voltage) to ensure that the system runs in the best working condition.

Solar photovoltaic (pv) systems use in expanding, especially off-grid solar pv system, into homes as household electrical appliances such as refrigerators (compressor) when they start, electric cars and motor power, because this kind of mechanical and electrical equipment to start large current, starting with current is often 10 times the rated working current of 5 a. The solar cell module in the photovoltaic system is affected by the maximum short-circuit current and the limitation of light intensity, so it is difficult for the photovoltaic cell array to meet the requirements of the starting current. If the battery is applied, it can supply a large current to the load to start at a moment.

In most off-grid PV systems, the voltage and current generated by the array arrangement of PV cells (solar panels) cannot be exactly the same as the load (appliance).  Especially when the natural conditions change, cloudy, rainy, night light intensity changes, photovoltaic cells can not supply full load of energy, resulting in the normal use of electrical appliances (load) difficulties.  With the storage battery for energy storage, and can regulate its energy metabolism, photovoltaic system with energy storage device, can satisfactorily and smoothly supply electrical energy required. Therefore, it is necessary to use energy storage batteries to store energy for photovoltaic systems.