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Photovoltaic + Energy Storage, How To Choose An Energy Storage System?

Under the requirements of carbon peaking and carbon neutrality, the proportion of new energy sources in my country continues to rise, and “photovoltaic + energy storage” has become the standard for more and more photovoltaic development. The combination of energy storage will bring long-term sustainable development of photovoltaics. power. So, what are the application scenarios of energy storage, how to choose a suitable solution for photovoltaic + energy storage, and how to operate the solar energy storage system efficiently? In this article, we will introduce them one by one.

  1. What are the typical application scenarios of energy storage?

Energy storage refers to the process of storing energy through media or equipment and releasing it when needed. Traditional energy storage technologies are divided into mechanical energy storage, electrochemical energy storage, chemical energy storage, electromagnetic energy storage, thermal energy storage, etc. At present, the most common applications are mechanical energy storage and electrochemical energy storage.

Taking electrochemical energy storage as an example, according to the installation location in the power system, the application scenarios of energy storage can be roughly divided into three scenarios: power generation side energy storage, grid side energy storage and user side energy storage. That is, the power generation side, the grid side, and the user side.

Application Diagram of Energy Storage Scenario

Power generation side energy storage power station

The main application scenarios of energy storage power stations on the power generation side include smooth output of renewable energy, promotion of new energy consumption, and frequency regulation auxiliary services.

Schematic diagram of energy storage participating in AGC frequency regulation service

Grid side energy storage power station

The main application scenarios of grid-side energy storage power stations include grid power supply, grid peak regulation, delaying grid transformation and upgrading, grid terminal voltage support, and reactive power compensation.

Application scenarios of energy storage grid side

User-side energy storage power station

The application scenarios of user-side energy storage are relatively common. The main application scenarios include peak-valley difference arbitrage for large users, promotion of distributed energy consumption, improvement of energy quality, and participation in demand response.

01 Peak and Valley Arbitrage

The peak-valley difference arbitrage for large users absorbs excess electricity for storage during the low electricity price period, releases it when the electricity price is high, and uses the peak-valley electricity price difference to realize the profit of the user side.

02 Promote assimilation

Promote distributed energy to absorb a large proportion of distributed new energy power sources in the microgrid system, and configure the energy storage system to adjust the balance between power generation and load, and maximize the use of renewable energy.

03 Improve energy quality

To improve energy quality, energy storage can be controlled by power electronic devices, and the redundant capacity of energy storage can be used to manage power quality problems such as low power factor and voltage imbalance in the production process.

04 Participate in Demand Response

The demand response energy storage system participates in demand response through high storage and low discharge, and obtains subsidies or preferential electricity prices.

Growatt user side energy storage case
  1. What are the typical system solutions of photovoltaic + energy storage?

Let’s take the photovoltaic + energy storage scenario as an example. At present, there are mainly AC-side coupling schemes and DC-side coupling schemes on the market for solar-storage integration schemes.

AC side coupling scheme

The AC side coupling scheme means that photovoltaic and energy storage are connected on the AC side, and the energy storage system can be connected to the low-voltage side, or it can be centrally connected to the 10kV ~ 35kV busbar. This solution is generally applicable to larger photovoltaic power stations, where the energy storage system is centralized and easy to operate, manage and dispatch.

Optical storage AC coupling wiring diagram DC side coupling scheme

The DC side coupling scheme means that the energy storage system is connected to the DC side, and there are few power conversion links between the two systems, low energy loss, and low equipment investment. This solution is generally suitable for small and medium-sized energy storage systems, and the photovoltaic Growatt inverters in the system need to reserve energy storage interfaces.

Optical storage DC coupling wiring diagram
  1. How to operate and manage the optical storage system efficiently?

From application scenarios to solution selection to system integration, the safe operation and revenue optimization of photovoltaic energy storage power plants in the life cycle are also closely related to the control, operation and management of the entire system.

Compared with the traditional economic dispatch mode of power plants, the photovoltaic power generation system needs to fully consider the effective management of photovoltaics, energy storage batteries, and PCS when dispatching, so as to improve the safety of the entire photovoltaic power plant operation. and economy.

Taking the stabilization of the fluctuation of the photovoltaic system as an example, the energy storage system can smoothly control the photovoltaic output of photovoltaic power generation, and set the smoothing rate parameter. The output power is within the range of the set rate of change.

Based on photovoltaic power prediction and millisecond response characteristics of energy storage, the EMS system can smoothly control the photovoltaic system, reduce the impact on the power grid, and improve the stability and reliability of the power grid operation. At the same time, a millisecond-level fast linkage mechanism is built between the various levels of the BMS, PCS and EMS to maximize the safety of the battery and the entire system.

Growatt Energy Management Interface

Conclusion:

Although the energy circle has long recognized that “energy storage is an important means to solve the intermittency and volatility of new energy sources such as photovoltaics and wind power, and to promote consumption and reduce abandonment of wind and light”, the approach of the era of comprehensive parity has also made this advantage even more prominent , but its development has been slow due to cost constraints. In order for energy storage to complete the gorgeous transformation from “icing on the cake” to “just demand in the market”, it not only needs clearer and more powerful policy support, but also promotes the industry’s own development and transformation through technological and product innovation.

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