Energy Storage Knowledge Class | Analysis of the Efficiency of C&I Energy Storage Systems

In the industrial and commercial sectors, energy storage systems are playing an increasingly crucial role, and system efficiency is one of the core indicators used to measure their performance. For companies that profit by arbitraging peak-valley price differences, the efficiency of the energy storage system directly impacts their economic benefits and return on investment (ROI).

Energy Storage System Conversion Efficiency Calculation Formula

According to the Chinese GB/T 51437-2021 "Design Standards for Wind-Solar-Storage Hybrid Power Stations," the efficiency of energy storage devices should be calculated based on factors such as battery efficiency, power conversion system efficiency, electrical line efficiency, and transformer efficiency, using the following formula:

Φ=Φ1×Φ2×Φ3×Φ4

• Φ1: Battery Efficiency — the efficiency of the energy storage battery in completing charge and discharge cycles, which is the ratio of energy discharged by the battery to the energy charged into it. Battery efficiency is closely related to factors such as the battery's depth of discharge (DOD), charge-discharge rate, and temperature, in addition to the battery's inherent characteristics.
• Φ2: Power Conversion System (PCS) Efficiency — including rectifier efficiency and inverter efficiency.
• Φ3: Electrical Line Efficiency — considering the efficiency after losses from bi-directional power transmission in AC/DC cables.
• Φ4: Transformer Efficiency — considering efficiency losses from bi-directional voltage transformation in transformers.

How to Evaluate the Efficiency of an Energy Storage System?

The most straightforward method is to check the charge and discharge data from system operation. However, how can we evaluate this before selecting the system? We mainly analyze the following aspects:

1. Device Selection
2. System Integration Design
3. EMS (Energy Management System) Strategy The EMS management strategy of an energy storage system also affects overall system efficiency. A smart EMS can optimize the charge and discharge strategies of the energy storage system based on weather conditions, peak-valley electricity price periods, the battery's state of charge (SOC), and the user's electricity load. This ensures coordinated optimization between the energy storage system and the load, improving overall energy efficiency.
4. Operation and Maintenance Management Establishing a data monitoring platform for the energy storage system to collect operational data in real-time is crucial. In-depth data analysis helps identify the key factors affecting system efficiency, and appropriate optimization measures can be implemented. Regular maintenance and timely replacement of aging or damaged components ensure the system maintains optimal operational status.

In addition to the energy storage system's conversion efficiency, there is also the concept of overall power station efficiency. According to GB/T 36549-2018 "Operational Indicators and Evaluation of Electrochemical Energy Storage Power Stations," the comprehensive efficiency of an energy storage power station refers to the ratio of the total electricity supplied to the grid to the total electricity received from the grid during the evaluation period:

Comprehensive Efficiency = Total energy supplied to the grid by the energy storage power station / Total energy received from the grid by the energy storage power station.

Thus, the comprehensive efficiency formula requires not only the calculation of the energy storage system's AC/DC conversion efficiency but also the power loss from auxiliary devices such as air conditioning, fire protection systems, lighting, monitoring, and alarms. These auxiliary systems consume electricity during operation and affect the overall efficiency of the energy storage power station.

Vilion's self-developed AiP (Active in Parallel) Cluster-Level Equalization Core Technology effectively builds multi-cluster parallel scenarios, ensuring that new and old batteries can be easily mixed and used together, reducing energy loss to zero and increasing the efficiency of the energy storage system by 2%.

In conclusion, the efficiency of industrial and commercial energy storage systems is a complex performance metric involving various factors. Understanding the operating principles, influencing factors, and methods of improvement is crucial for customers to make informed choices in selecting and applying energy storage systems. With continuous technological advancements and innovations, energy storage system efficiency is expected to improve further, providing a stronger boost to the sustainable energy development of industrial and commercial sectors.

For more information on energy storage products, click here: Enenrgy Storage Technology-Vilion (Shenzhen) New Energy Technology Co., Ltd.