Differences Between Commercial and Industrial Energy Storage and Utility-Scale Energy Storage

Energy storage is gaining popularity as an important complement to renewable energy sources. Among energy storage systems, commercial and industrial energy storage and utility-scale energy storage are two notable solutions that have emerged in recent years. However, they have different application scenarios and technical features. This article will elaborate on the differences between these two types of energy storage systems from multiple dimensions.

Application Scenarios

C&I energy storage is mainly applied to the self-supply power of commercial and industrial users which includes factories, buildings, data centers, etc. The purpose is to reduce peak-valley electricity tariff for users and improve the reliability of power supply.

Utility-scale energy storage is mainly applied to the grid side. The purpose is to balance power supply and demand, regulate grid frequency, and achieve peak-valley regulation. It can also provide spare capacity and other power regulation services.

Capacity

The capacity of C&I energy storage is generally in the range of several tens to hundreds of kilowatt-hours, mainly depending on the user’s load size and tariff demand. The capacity of ultra-large-scale C&I systems generally does not exceed 10,000 kWh.

The capacity of utility-scale energy storage ranges from several megawatt-hours to several hundred megawatt-hours, matching the grid scale and demands. For some large grid-level projects, the capacity of a single site can reach hundreds of megawatt-hours.

System Components

·Battery

C&I energy storage requires relatively low response time. Comprehensively considering costs, cycle life, response time and other factors, batteries with energy density as the priority are used. Utility-scale energy storage uses power density focused batteries for frequency regulation.

In fact, most large-scale energy storage also uses batteries with energy density as the priority. But since they need to provide power ancillary services, the battery systems of energy storage power stations have higher requirements for cycle life and response time. Batteries used for frequency regulation and emergency backup need to select power-type batteries.

·Battery Management System (BMS)

Small and medium-scale C&I energy storage systems can provide the battery pack with a variety of protection functions, such as overcharging, over-discharging, over-current, overheating, under-temperature, short-circuit and current limitation. It can also equalize the voltage of the battery pack during the charging process, configure the parameters and monitor the data through the background software, communicate with different types of power conversion systems, and carry out intelligent management of the whole energy storage system.

The energy storage power station can manage individual batteries, battery packs and battery stacks in a hierarchical manner. Based on their characteristics, various parameters and operating statuses of the batteries can be calculated and analyzed to achieve balancing, alarm and effective management. This allows each group of batteries to produce the same output, ensuring that the system achieves the best operating state and the longest use time. This provides accurate and effective battery management information. Through battery balancing management, the energy utilization efficiency of batteries can be greatly improved and load characteristics optimized. At the same time, the service life of batteries can be maximized to ensure stability, safety and reliability of the energy storage system.

·Power Control System(PCS)

The inverters used in C&I energy storage have relatively simple functions, mainly bidirectional power conversion, smaller sizes, and are easier to integrate with battery systems. Capacity can be flexibly expanded as needed. The inverters can adapt to a super wide voltage range of 150-750 volts, meeting the series and parallel connection requirements of lead-acid batteries, lithium batteries, flow batteries and other batteries, and achieving unidirectional charging and discharging. They can also match different types of photovoltaic inverters.

The inverters used in energy storage power stations have wider DC voltage ranges, up to 1500 volts for full load operation. In addition to the basic power conversion function, they also need to have grid-coordinated functions, such as primary frequency regulation, fast source-grid-load dispatching, etc. They have stronger grid adaptability and can achieve fast power response.

·Energy Management System (EMS)

Most of the EMS of C&I energy storage systems do not need to accept grid dispatching. Their functions are relatively basic, only needing to do local energy management, namely supporting battery balancing management, ensuring operational safety, supporting millisecond fast response, and achieving integrated management and centralized control of energy storage sub-system equipment.

However, utility-scale energy storage such as energy storage power stations that need to accept grid dispatching have higher requirements for the EMS. In addition to basic energy management functions, they also need to provide grid dispatching interfaces and energy management capabilities for micro-grid systems. They need to support multiple communication protocols, have standard power dispatching interfaces, be able to conduct energy management and monitoring for application scenarios such as energy transfer, micro-grids, and power frequency regulation, and support the complementation and monitoring of multiple systems such as power sources, grids, loads, and energy storage.