Application of energy storage technology in photovoltaic industry

Energy storage technology and PV systems

The configuration of energy storage technology in photovoltaic power plants is mainly to provide new energy consumption, auxiliary implementation of primary frequency regulation and other services. In addition, energy storage power stations can also participate in power market transactions such as peak shaving and frequency regulation, and receive some of the benefits.

● Current situation of  power generation

Photovoltaic power generation fluctuates greatly, especially in some remote areas. The power grid often cannot completely absorb wind and photovoltaic power generation, and the application of energy storage technology can reduce or avoid the abandonment of light.

When the energy storage system is installed on the side of the renewable energy power station, once the grid operation system is at the peak of power or the transmission channel is abnormal, the power generation conditions of some power sources are affected by external objective environmental factors.

● Improvement of power quality

The actual power generation conditions will be constrained, and in the power generation process, the power quality and operation effect released by the power supply farm cannot meet the preset requirements.

In the process of power transmission of various renewable energy sources, the power generation effect of renewable energy sources such as wind power will be unstable.  By deploying a larger energy storage capacity in a centralized renewable power station, the joint output of the station and energy storage technology can be realized.

At the same time, the renewable system of energy storage companies in China should be combined with the current power generation situation and ensure that the total output of electric energy meets the preset working requirements.

The status of the energy storage technology

Different power generation modes will affect the power generation effect of renewable energy such as electricity to a certain extent, so it is necessary to combine different energy storage technology with different intrinsic characteristics. Battery energy storage technology has high energy density and power density at the same time, which determines its wide technical applicability and good development market.

● Energy storage type

Energy storage technology is divided into mechanical energy storage, electrical energy storage, battery energy storage, thermal energy storage, and chemical energy storage. The energy storage battery is the core part of the energy storage system.

At present, the mainstream batteries on the market can be roughly divided into lithium ion batteries, sodium ion batteries and lead carbon batteries according to different energy storage technology routes. The battery response speed and discharge efficiency of different energy storage technology routes are different.

● Lifepo4 battery energy storage

According to the different cathode materials, the current mainstream lithium ion batteries have two categories: ternary and lithium iron phosphate.  Lithium iron phosphate batteries have lower energy density than ternary materials and lower costs. Energy density requirements in the field of lithium ion battery storage  are not high, and lifepo4 battery with low cost and long life are preferred.

● Sodium ion battery energy storage

Sodium ion batteries have excellent performance. According to the latest advances in sodium ion battery energy storage system, it performs well in terms of safety and availability of material resources. After large-scale application, the cost is expected to be lower than that of lithium iron batteries. It is expected to complement and effectively replace lithium-ion batteries.

● Lead-carbon battery energy storage

Lead-carbon battery is a capacitive lead-acid battery, which is a technology developed from traditional lead-acid batteries. Although the initial investment cost of lead-carbon batteries is low, the benefits are not obvious because their discharge depth is lower than other forms of energy storage.

In addition, if the cost of energy loss in actual use is considered, lead-carbon batteries will be at a certain disadvantage due to their lower energy efficiency than iron-lithium batteries.

Application of energy storage technology

● Application in power peak shaving

When electricity is at its peak, the load pressure on the high-power grid should be reduced. A large amount of energy is stored when the load is low, and the energy collected is released at the highest load, ensuring the safety and stability of the system operation on the basis of effective load discharge power supply.

● The use of microgrids

In the process of transmission and distribution network development, microgrid integration is its main development mode.

Scientific integration into relevant grid processing technology can improve the overall effect of the grid operation system.

The island classification operation mode is adopted to organically separate the microgrid system and the system, and the operating architecture of each subsystem is separated.

Energy storage technology outlook

At present, energy storage services lack a clear and quantitative market pricing system and mechanism, and the single diffusion recovery model is not attractive enough, coupled with technical costs and potential safety risks. The problem can be solved in the following ways:

• Strengthen grid-connected management and lead the safe development of electrochemical energy storage facilities.
• Determine energy storage facilities in key areas such as grid connection, metering, safety, and fire protection.
• Clarify the technical requirements and business handling procedures for grid-connected security.
• Lead the safe development of energy storage facilities on the power generation side and the user side.
• Actively track and study the development of energy storage.

• In line with the development trend of the times, establish a sound energy development mechanism.
• Expand the scope of renewable energy storage to promote the sustainable development of energy sources.
• The power management department should further optimize the structure of relevant energy storage development equipment.

Conclusion

The application of energy storage technology in photovoltaic power generation systems involves many aspects. Power generation enterprises should properly coordinate the implementation of energy storage technology conditions and influence factors, while eliminating risk factors from all walks of life.