Energy storage battery mainly divided into the following points:

(1) for storing electrical energy

In the majority of off-grid PV system, photovoltaic cells ( solar panels ) array arrangement produced by the voltage, current and can not be completely consistent load (household appliances). Especially when the change of the natural conditions, cloudy day, rainy day, night light intensity changes, photovoltaic cells cannot provide full of energy, to electrical ( load ) normal use difficult. A battery to store energy, and can adjust the energy metabolism, photovoltaic system with energy storage device can be satisfied, smoothly for electrical appliances to provide the required electric energy. So the battery for photovoltaic energy storage system is very necessary.

(2) adjust the voltage ( steady voltage )

As a result of the solar battery performance by sun light ( irradiation ) intensity, temperature and other factors change, so the solar cell module if directly is connected with a load when the load is often difficult in the best working condition, the system efficiency is very low. But when the battery energy storage battery when in use, the solar cells working voltage" clamp" role, transform for solar energy storage battery, by the energy storage battery smoothly ( especially voltage ) power to the load, ensure the system in optimal working condition.

(3) to provide instantaneous large current discharge

Solar photovoltaic system uses in expanding, especially off-grid solar photovoltaic system, into thousands of households will be used as household appliances such as refrigerators ( compressor ) promoter, electric cars and motor power, because this kind of mechanical and electrical equipment to start large current, starting current is often rated current5a10 times. Photovoltaic system solar cell components by the maximum short circuit current and the influence of light intensity limit, photovoltaic cell arrays are very difficult to deal with the starting current requirements, if the application can instantaneously provide high current battery to the load starting.