In recent years, energy storage systems have developed rapidly, especially in the context of significant cost reductions in the photovoltaic and lithium battery industries. Many applications that were previously too expensive to be used in large quantities can now be widely deployed. Photovoltaic power generation, residential energy storage, commercial and industrial energy storage, electric vehicles, and charging stations are rapidly expanding globally.
Why do people use lithium battery more in energy storage system?
Energy storage systems are not a very new product. They were widely used during World War II, especially on German U-boats, also known as the Atlantic Wolfpack, where lead-acid batteries were used extensively. When the submarines were travelling on the surface, the diesel generator charged the lead-acid batteries while also providing power to the ship. Once the submarine submerged, it relied on the batteries for power.
Due to the low energy density of lead-acid batteries, submarines cannot operate for long periods underwater and must regularly surface to recharge. This makes them vulnerable to attack, and many German submarines were destroyed on the surface.
The discharge curve of lead-acid batteries is very simple, and their low energy density makes it easy to determine the remaining charge based on voltage. For a long time, there was no battery management system, and it did not affect normal use. However, with the widespread commercial use of lithium-ion batteries, the situation has fundamentally changed.
The energy density and cycling lifespan of lithium batteries exceed that of lead-acid batteries by more than five times, and even higher. The energy density is too high, and if not managed properly, it can lead to major problems such as combustion or explosion.
Taking the most commonly used lithium-ion and lithium iron phosphate batteries as an example, the nominal voltage of a single lithium-ion battery cell is 3.7V, and the nominal voltage of a lithium iron phosphate battery is 3.2V. In the early days, lithium batteries were used with single or two cells connected in series to output a voltage of 3.7V or 7.4V, with simple applications and low requirements for battery consistency.
What benefits does lithium battery bring to Energy Storage System?
As we all known that, lithium batteries play a crucial role in energy storage systems, offering numerous advantages such as high energy density, long cycle life, and reliable performance. As renewable energy sources like solar and wind become increasingly integrated into the grid, efficient and scalable energy storage solutions are essential for balancing supply and demand. Lithium batteries provide a viable solution for storing excess energy generated during periods of low demand and releasing it when demand peaks.
Energy storage systems based on lithium batteries enable numerous benefits:
Grid Stability: By storing and releasing electricity as needed, lithium battery systems contribute to grid stability and reduce the reliance on fossil fuel-based power plants. They help mitigate the challenges posed by intermittent renewable energy sources, ensuring a steady and reliable power supply.
Peak Shaving and Demand Response: Lithium battery energy storage systems allow for peak shaving, where stored energy is discharged during periods of high electricity demand. This helps reduce strain on the grid during peak load hours and can potentially lower electricity costs. Additionally, these systems enable demand response programs, allowing users to adjust their electricity consumption patterns to better align with supply and demand fluctuations.
Integration of Renewable Energy: Lithium battery energy storage systems facilitate the integration of renewable energy sources into the grid. They enable efficient capture and storage of excess energy generated by renewable sources during favorable conditions, such as sunny or windy days. This stored energy can then be utilized during periods of low renewable energy generation or high demand.
Backup Power and Resilience: Lithium battery energy storage systems provide backup power in case of grid outages or emergencies, ensuring continuous power supply for critical loads. They enhance the resilience of homes, businesses, and even entire communities, enabling them to operate independently from the grid during unforeseen circumstances.
Environmental Benefits: Lithium battery energy storage systems contribute to reducing greenhouse gas emissions and combating climate change. By enabling the integration of renewable energy sources, they help displace fossil fuel-based generation, thus reducing carbon dioxide and other pollutants released into the atmosphere.
How to Make Your Energy Storage System Safer?
However, as the energy storage capacity increases, the voltage also becomes higher. Taking the example of a 300V car three-element battery pack, about 81 cells need to be connected in series. At this point, the consistency of the battery is very high. If the consistency is not up to standard, some of the smaller capacity cells in the series will be fully charged first during charging and discharged first during discharge, which will cause overcharge or overdischarge. Once such a situation occurs one or two times, the lithium battery will be scrapped, and serious consequences such as fire or explosion may occur.
At this point, it is necessary to have a Battery Management System (BMS) to effectively manage the battery. It can accurately manage each cell of the battery pack in real-time, keeping each cell in the best condition. If any problems are detected, it can provide protection and warnings in the first time to prevent dangerous situations.
If in some situations where the stored energy is not large, the charging and discharging power is relatively small, and the changes are relatively gentle, a lithium battery pack with only hardware-controlled BMS is sufficient. However, for high-power energy storage products, a lithium battery pack with communication function is necessary.
Because the working characteristics of lithium batteries are different under different voltage, current, capacity, and temperature, and there may be slight differences in cells from different manufacturers, which the inverter cannot know. Therefore, it is necessary for the lithium battery pack to inform the inverter of its real-time working status. After knowing these statuses, the inverter will adjust its control strategy to keep the lithium battery in the best working condition, greatly improving the battery’s lifespan and safety.
Therefore, for energy storage systems that consume more than 5 kWh, communication function is a must. As a netizen pointed out, another benefit of lithium battery packs with communication function is that the operating conditions of each cell can be checked through the network, but not all platforms will show this data to customers.
Generally, there will be RS232/RS485/CAN interfaces on battery packs. A friend asked, which one should I use? It is recommended to use them in the order of CAN/RS485/RS232. When there are many battery packs, it is strongly recommended to use the CAN bus. Many cars and trains use the CAN bus, which shows that its safety and speed are the best.
In summary, lithium battery energy storage systems offer a versatile and sustainable solution for managing energy supply and demand, promoting grid stability, and supporting the transition to a cleaner and more resilient energy future. As advancements in lithium battery technology continue to drive improvements in performance and cost-effectiveness, these systems are poised to play an increasingly vital role in our quest for a sustainable energy ecosystem.