3 Models of Common Photovoltaic Energy Storage Systems

Author:BSLBATT    Publish Time: 2021-11-01

Solar photovoltaic (PV) power generation is one of the important components of the strategy to achieve sustainable development of global energy and electricity. Due to the highly volatile and random nature of photovoltaic output power, the instability of photovoltaic power severely restricts the access and transmission of photovoltaic power. Energy storage battery technology can achieve peak shaving, load tracking, frequency regulation and voltage regulation, power quality management and other functions.

The PV energy storage system can also deposit excess power into the storage battery when the PV power station encounters light abandonment and limits power generation, and send the power in the battery to the grid through the storage inverter when the PV power generation is lower than the limit value or when the power consumption peaks at night, the energy storage system participates in the grid peak shaving and valley filling, the energy storage system can also use the peak and valley electricity price difference to create greater economic benefits and improve the system's own regulation capacity; the PV energy storage system is used as An effective support technology to solve the problem of large-scale renewable energy generation to the grid.

The main models of energy storage systems are energy storage systems configured on the DC side of the power supply, energy storage systems configured on the AC side of the power supply and energy storage systems configured on the load side.

1. Energy storage system configured on the DC side of the power supply

Energy storage systems configured on the DC side of the power supply can mainly be installed in DC systems such as photovoltaic power generation, and this design allows the battery combination photovoltaic power generation array to be mated and regulated in the DC section of the inverter.

The PV power system and the battery storage system in this system share an inverter, but due to the large differences between the charging and discharging characteristics of the battery and the output characteristics of the PV array, the maximum power tracking system (MPPT) in the grid-connected PV inverter in the original system is specifically designed to match the PV output characteristics and cannot meet the output characteristics curve of the storage battery at the same time.

Therefore, such systems need to be modified or redesigned and manufactured so that the inverter can not only meet the inverter requirements of the PV array, but also add functions such as charge and discharge controller for the battery bank, and battery energy management. Generally speaking, the system is unidirectional, meaning that the batteries in the system are fully charged by the photovoltaic power, and the power from the grid is not available to charge the batteries.

The main features of this model are the high efficiency of the system, the fact that the power output from the power station can be dispatched from within the PV power station, the seamless connection that can be achieved, the good quality of the output power, the very small output fluctuations, etc., which can greatly improve the smoothness, stability and adjustable performance of the PV power output, the disadvantage is that the inverter used needs to be The disadvantage is that the inverter used requires a special design and is not suitable for upgrading most existing PV plants that have already been installed. Another disadvantage is that the battery bank in this storage system can only receive electricity from this generation unit to charge it, while the excess electricity from other nearby PV generation units or power stations cannot charge it. This means that this solution lacks the ability to deploy power within a large power station.

2. configured in the power supply AC side of the energy storage system

Configured in the power supply AC side of the energy storage system can also be called configured in the AC side of the energy storage system, unit type AC side of the energy storage mode, it uses a separate charge and discharge controller and inverter to charge the battery or inverter, this solution is actually to the existing photovoltaic power generation system outside a storage device, can be installed in any kind of photovoltaic power station or even wind power station or other power station to upgrade This model overcomes the problem that DC-side energy storage systems cannot be dispatched in a uniform manner, as the charging or discharging of the system is controlled by an intelligent control system or by the grid. It can not only concentrate the excess power in the whole station to charge the storage system quickly and effectively, but also dispatch the cheap low valley excess power from the grid outside the station, making the system operation more convenient and effective.

Another model for AC-side access is to connect the storage system to the grid side. Obviously, these two types of energy storage systems differ only in their access points, with the former having the energy storage part connected to the AC low voltage side, sharing a transformer with the original PV plant, and the latter having the energy storage system form a separate storage plant model, connected directly to the high voltage grid.

The AC side access solution is not only suitable for grid energy storage, but is also widely used in relatively isolated areas such as islands to form relatively independent mini-grid power supply systems. The AC-side access energy storage system can be implemented not only on new power stations, but also on existing power stations which can be easily retrofitted and additionally built. The circuit structure is clear, the power generation and storage fields can be built on separate sites, with less direct interconnection and therefore also easy to operate and control and maintain. The disadvantage is that as power generation and energy storage are independent of each other, coordination and control between them requires a special intelligent control and dispatch system, so the cost is relatively high.

3. configured in the load-side energy storage system

Configured in the load side energy storage system mainly refers to emergency power and mobile electric equipment, such as rechargeable electric vehicles, electric tools and mobile phones.

This paper only discusses the technical aspects of energy storage power stations, although they have many advantages and can be implemented and applied in some special occasions, but due to the current battery efficiency, environmental protection, long life and low prices and other key issues have not been a major breakthrough in the current large-scale promotion of energy storage power stations may have feed-in tariffs, subsidy policies and other issues.

About BSLBATT ESS battery

BSLBATT Power designs and manufactures efficient, non-toxic and long-lasting energy storage and management systems using non-toxic Lithium Iron Phosphate (LFP).Based in Huizhou, Guangdong, China, BSLBATT combines non-hazardous LFP energy storage chemistry with its proprietary battery and cell architecture, manufacturing processes and materials, power electronics and battery management systems (BMS) to create safe, reliable, durable and highly scalable - demand power solutions for the residential, commercial, industrial, military, emergency back-up and telecommunications industries. Integral to all BSLBATT ESS battery solutions is a proprietary management system that further optimises the lifecycle, performance and durability of its batteries. bslbatt storage system components are 3C, CE, TUV certified and have passed various stringent tests and requirements.

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