On November 12, the National Energy Administration released the “Guiding Opinions on Promoting the Integrated Development of New Energy,” aiming to shift new energy from “individual efforts” to “integrated development.” For those working in the new energy industry, expanding their knowledge base is crucial; a comprehensive understanding of wind, solar, energy storage, and charging technologies is essential.
Meanwhile, for park managers or factory owners who want to respond to the call to build low-carbon and zero-carbon parks that complement multiple energy sources such as photovoltaics and energy storage, it is also necessary to have a certain understanding of energy storage. Today, TAICO will bring you some basic knowledge about energy storage.
System Scale: Understanding MW and MWh
When discussing an energy storage project, we often hear terms like “MW/MWh” used to describe its scale. So, what do these two units actually represent?
MW: The system’s “power,” highlighting its instantaneous explosive force.
This refers to the maximum rate at which an energy storage system can store or release energy per unit of time. It determines the battery’s response speed and its ability to handle high-power applications.
For example, in applications requiring rapid grid frequency response, energy storage systems need to quickly release energy to stabilize the grid frequency; and in mitigating instantaneous fluctuations in renewable energy sources, energy storage may be necessary to meet peak load surges from industrial users.
MWh: The system’s “energy,” representing its capacity.
This refers to the total amount of electricity that an energy storage system can store when fully charged. It determines the “range” of continuous discharge at a certain power, just as the fuel tank capacity of a car determines the distance the car can travel.
Long/short time energy storage
Let’s start with the ratio of MW to MWh.
Why combine MW and MWh in our descriptions? What is the significance of their ratio?
This leads to an important derivative indicator in the energy storage field—energy storage duration, which is the origin of the terms “long-duration energy storage” and “short-duration energy storage.”
Energy storage duration can be calculated using the formula:
“MW (rated power) / MWh (stable capacity) = P/E”.
For example, if an energy storage power station is configured with 50MW/100MWh, then P/E = 0.5P, and the system discharge duration is 2 hours; if it is 100MW/100MWh, P/E = 1P, corresponding to a 1-hour system.
For energy storage power stations of the same capacity, the larger the rated power, the shorter the system discharge duration.
Charge/Discharge Rate
When the energy storage system is 50MW/100MWh, the concept of battery charge/discharge rate needs to be introduced to achieve a specific discharge duration.
C is the unit used to represent the battery charge/discharge rate.
Charge/discharge rate = charge/discharge current / rated capacity. For example, a battery with a rated capacity of 100Ah discharged at 50A has a discharge rate of 0.5C.
To better understand, consider a simple example: a water tank = battery, charging/discharging water = charging/discharging, and the diameter of the water pipe = the magnitude of the charging/discharging current.
1C means using a “standard” diameter water pipe, which can charge/discharge the entire tank of water in one hour.
2C means using a water pipe twice the diameter, which can charge/discharge the water in half an hour. Conversely, 0.5C means using a water pipe half the diameter, which takes two hours to charge/discharge.
When selecting commercial and industrial energy storage equipment, a higher rate is not always better. An excessively high rate can lead to violent internal reactions in the battery, potentially shortening its cycle life. The rate of increase is too low, but the charging and discharging speed is too slow, so it cannot make full use of the peak-valley price difference, and the economic efficiency is not very good.
Different energy storage devices with different capacity ratios can be selected according to different scenarios.
1C energy storage is characterized by fast response and emergency backup, but it has high heat generation, short lifespan, and high cost. It is suitable for high-power short-term applications such as frequency regulation, black start, and emergency backup.
0.5C energy storage offers a relatively gentler charging and discharging rate, resulting in a longer lifespan and more stable efficiency. Furthermore, peak-valley electricity pricing in most provinces lasts only 2-3 hours, and a 0.5C system can complete charging and discharging within just two hours. This timing is ideal, and the battery lifespan won’t decline too quickly, making it the mainstream choice for industrial and commercial energy storage and peak shaving.
0.25C type energy storage is suitable for long-term energy transfer scenarios such as long-term energy storage, cross-day peak shaving, and photovoltaic-energy storage integration. It is economical but has a slower response time
In general, a higher rate of charge/discharge results in faster charging and discharging, but also puts more stress on the battery; a lower rate of charge/discharge results in a longer lifespan, but also longer charging and discharging times.
Therefore, choosing the C-value is essentially a balance between performance and lifespan.
Cycle life
Now that we’ve discussed battery charge/discharge duration and speed, let’s talk about cycle life. Just like our phone batteries, after prolonged use, even after a short time of full charge, the battery level drops rapidly. This indicates that the State of Health (SOH) is deteriorating.
If a battery has a nominal capacity of 10 kWh, but after use and degradation, even when fully charged, it only has 8 kWh remaining, then the battery’s health status is only 80%, indicating that the battery should be replaced. By monitoring the State of Health (SOH) value, the end-of-life time of the battery can be predicted, allowing for appropriate maintenance and management.
Energy storage batteries are no exception to this problem. Moreover, due to the large scale of investment in industrial and commercial energy storage, this issue has received even more attention.
So, how should we understand the cycle life of an energy storage battery? It refers to how many times the battery can completely go through the process of “fully charged → fully discharged” before its health condition reaches a certain value under certain charging and discharging conditions.
Note that it calculates a complete charge-discharge cycle.
For example, if the battery is charged to 50% and then discharged completely, this only counts as half a cycle. It needs to be charged to 50% again and then discharged completely to complete a full cycle.
Assuming a storage battery has a cycle life of 6,000 cycles, and operates on a cycle of two charge and two discharge cycles per day, with 330 working days per year, the number of cycles per year would be 660. In theory, the storage battery could be used for 9-10 years.
Of course, there are many members in the energy storage battery family, and their cycle lives vary significantly. You can choose the appropriate battery type based on your specific needs.
Parameter comparison (Lifepo4 Battery Cell，Lithium Ion Battery Cell And Solid-state battery)
| Parameter Dimensions | Solid-state Battery | Lifepo4 Battery Cell | Lithium Ion Battery Cell |
| Cycle life | 10,000 times | 8,000 times | 3,000 times |
| Energy density | 500Wh/kg | 190Wh/kg | 100Wh/kg |
| Warranty | 5-year warranty + lifetime maintenance | 5-year warranty + lifetime maintenance | 3-year warranty |
| Operating temperature | -40°C-85°C | -20°C -60°C | -20°C -60°C |
TAICO solid-state batteries, based on their independently developed high-temperature stable ceramic electrolyte (withstanding temperatures ≥900℃), completely eliminate the need for separators and liquid electrolytes, achieving a revolutionary breakthrough in safety performance and bringing four core advantages:
- Extreme Safety: The ceramic electrolyte is inherently non-flammable, fundamentally eliminating the risk of short-circuit fire. Even when subjected to puncture or extreme high-temperature environments, it ensures no fire or explosion.
- Leap in Energy Density: Energy density significantly surpasses that of traditional lithium batteries, greatly improving the overall energy efficiency of energy storage systems.
- Ultra-Long Cycle Life: Cycle life exceeds 10,000 cycles, far exceeding the lifespan of current mainstream battery products.
- Wide Temperature Range Adaptability: Stable operation in harsh environments ranging from -40℃ to 85℃, offering high deployment flexibility and wider applicability. Meanwhile, TAICO solid-state batteries combine excellent environmental friendliness with long-term cost-effectiveness, representing the core development direction of next-generation energy storage technology.
Furthermore, the cycle life of a battery is not only related to the charge/discharge rate (C) mentioned above, but also to the depth of charge/discharge (DOD).
DOD is used to measure the percentage of a battery’s discharged capacity relative to its rated capacity. The total amount of electricity discharged from the battery’s upper voltage limit to its lower voltage limit is defined as 100% DOD.
Generally, the deeper the discharge, the shorter the battery cycle life. A battery charge below 10% may be over-discharged, leading to irreversible chemical reactions that severely impact battery lifespan.
Chinese solid-state battery manufacturers
That concludes today’s sharing. You can also visit the TAICO website: taicoower.com to leave comments about what you’d like to see. If you find any errors in the article, please feel free to point them out and let’s discuss them together!
So if you have energy storage needs, contact us now!
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