According to different applications, solar energy storage systems are divided into off-grid energy storage systems, off-grid energy storage systems, grid-connected energy storage systems, and multi-energy hybrid micro-grid systems.

Grid-connected energy storage system

(1) Off-grid energy storage system

The off-grid energy storage system is also an off-grid solar power generation system with energy storage devices, which is specially used in areas without grids or areas with frequent power outages. Since the off-grid solar power generation system cannot rely on the power grid, it can only rely on the energy storage system for self-use to realize the working mode of “storage while using” or “storage first and use later”.

(2) Off-grid energy storage system

Off-grid solar power generation systems are widely used in frequent power outages, or solar grid-connected systems are self-contained and cannot be connected to the grid, the price of self-consumption electricity is much more expensive than the electricity price of the grid, and the peak electricity price is much more expensive than the valley electricity price. Compared with the grid-connected solar power generation system, the off-grid system combines the advantages of the off-grid system and the grid-connected system, which makes the application range wider and the power consumption more flexible. First, it can be set to output at the rated power when the electricity price peaks, reducing electricity costs; second, it can use the valley power to charge the energy storage system, use it during peak hours of electricity consumption, and use the peak-valley price difference to obtain income; third, when the power grid is out of power , the solar power generation energy storage system can be used as a backup power source to switch to an off-grid working mode to continue working.

(3) Grid-connected energy storage system

The grid-connected energy storage system can store excess solar power generation and increase the proportion of solar power generation for self-use. When the power generated by the solar power generation system is less than the power consumption of the load, the load is powered by the solar power generation and the grid together. When the power generated by the solar power generation system is greater than the power consumption of the load, part of the solar power generation is supplied to the load, and the other part is stored in the load. in the energy storage system.

In some foreign countries and regions where solar power generation systems were used earlier, after the cancellation of solar subsidies for previously installed household solar power generation systems, a grid-connected energy storage system is generally installed to allow solar power generation to be completely self-contained. This “plug-in” grid-connected energy storage system is well compatible with the inverter of the original system, and the original system does not need to be changed. When the energy storage system detects that there is excess electricity flowing to the grid, the energy storage system automatically starts to work and stores the excess electricity in the energy storage battery. When the energy storage battery is fully charged, the energy storage system can also connect to the user’s power A water heater converts excess electrical energy into heat and stores it. When the solar power generation system stops working in the evening, or when the user’s electricity consumption increases, the electric energy stored in the energy storage system can be used to supply power to the load. For large-scale solar power generation systems, other energy storage methods can also be used to store the required electric energy.

(4) Microgrid energy storage system

The microgrid can give full play to the application potential of various distributed clean energy, reduce the unfavorable factors such as small capacity of distributed clean energy, unstable power generation, low reliability of independent power supply, etc., and ensure the safe operation of the power grid, which is beneficial to the large power grid. Replenish. Microgrid applications are flexible, and the scale can range from thousands of watts to tens of megawatts. It can be operated as large as factories, mines, hospitals and schools, as small as a building or a home user.