The demand for energy storage system in photovoltaic power generation systems depends on various factors, including the scale of the photovoltaic system, operating mode, fluctuation of photovoltaic power, stability of the power grid, power generation mode of the system, electricity price structure, local energy policies, project economy, and market demand. Generally speaking, the following situations may require consideration of equipping energy storage systems:
However, generally speaking, it may be more appropriate to consider configuring energy storage systems in the following situations:
1. Large scale photovoltaic systems: When the installed capacity of photovoltaic systems is large, they may face significant power generation fluctuations and grid access restrictions. At this time, equipping energy storage systems can improve the smoothness and stability of the system's power generation.
2. Restricted grid access: If the grid access conditions in the location of the photovoltaic power plant are poor, the grid acceptance capacity is insufficient, or the peak output of the photovoltaic power plant does not overlap with the peak load of electricity, resulting in a high curtailment rate, configuring an energy storage system can improve the grid connection capacity of the photovoltaic power plant and reduce curtailment.
3. Electricity price structure: If there is a peak valley electricity price difference in the local area, or there are incentive mechanisms such as demand side response and auxiliary service markets, configuring energy storage systems can reduce electricity expenses by discharging during peak electricity prices and charging during low electricity prices, or obtain additional benefits by participating in the market.
4. Independent microgrid: In remote areas or microgrids, configuring energy storage systems can improve power supply reliability, reduce power outages caused by grid failures, and provide continuous power supply and energy storage scheduling functions.
5. Energy storage peak regulation is required: In situations where grid peak regulation or frequency regulation services are required, equipping energy storage systems can improve the flexibility and response speed of the system.

The specific configuration and operation of connecting the energy storage system to the photovoltaic system usually includes the following steps:

1. Requirement analysis: Clarify the grid connection conditions, electricity price structure, load characteristics, etc. of the photovoltaic power station, and determine the functional positioning and goals of the energy storage system.
2. System selection: Based on the analysis of requirements, select appropriate types of energy storage batteries (such as lithium iron phosphate batteries, lead carbon batteries, etc.), energy storage inverters (PCS), battery management systems (BMS), and other key equipment.
3. Capacity design: Based on factors such as the power generation capacity, electricity load, and price structure of the photovoltaic power station, the capacity and power of the energy storage system that needs to be equipped are determined through mathematical modeling and simulation analysis. Generally speaking, the capacity of energy storage systems should be comprehensively considered based on the instantaneous power, periodic power fluctuations, and demand response of photovoltaic power generation systems
4. System layout: Based on site conditions and safety requirements, determine the installation location and layout of energy storage batteries to ensure the safe operation of the system.
5. Configuration design: Design electrical connection schemes between energy storage systems, photovoltaic power stations, and power grids, including cable selection, switchgear configuration, and protection relay settings. Set the control parameters of the energy storage system, including charging and discharging strategies, power regulation methods, safety protection, etc.
6. Construction and installation: Carry out construction and installation according to the design plan, including the assembly of battery modules, installation and wiring of electrical equipment, etc.
7. Debugging and testing: After completing the construction and installation, debug and test the energy storage system to ensure that it can operate normally and meet the design requirements. Connect the photovoltaic system and energy storage system through power distribution devices to ensure smooth data communication and energy transmission between the two. Verify the coordinated operation of the photovoltaic system and energy storage system, and check the performance and stability of the system.
8. System maintenance: Regular operation, maintenance, and monitoring of the system to ensure the normal operation of the photovoltaic system and energy storage system.
By following the above steps, effective configuration and connection between photovoltaic systems and energy storage systems can be achieved, improving the power generation efficiency, stability, and flexibility of the system. In practical operation, detailed configurations and adjustments should be made based on specific scenarios and requirements. Meanwhile, when configuring energy storage systems, it is also necessary to consider factors such as safety, economy, and environmental friendliness to ensure the sustainable development of the project.