Next Generation BESS Technologies using 392Ah / 587Ah / 684Ah LFP Cells

This article discusses the upcoming trends in the BESS industry – 392Ah/587Ah/684Ah cells assembled into 6.25MWh/6.9MWh BESS containerized systems.

Why are BESS capacities getting bigger?

• Larger cells have lower costs, higher cycle life and higher efficiency.

• Larger systems have reduced assembly costs.

• Larger systems have lower balance-of-system costs.

• Larger systems have lower maintenance and lower failures.

• Larger systems utilise less land and fewer project-level balance of systems.

Three new generation cells and two new generation BESS technologies:

• 392Ah LFP prismatic cells are being adopted by companies that do not want to invest in new manufacturing lines and want to use the existing lines that produce 314Ah cells. The dimensions are very similar to 314Ah cells. While the 314Ah cell dimensions are around 72174207mm, the 392Ah cell dimensions are estimated to be 75182225mm (according to a manufacturer that launched a 392Ah cell).

• 587Ah/588Ah LFP prismatic cells are being planned in new manufacturing lines, and they can be either produced in a winding and lamination (Z stacking) process. These cells are undergoing final validation in pilot projects and will enter mass production soon. They are suited for 0.5C (2-hour) projects. They increase the existing 5MWh container capacity to 6.25MWh with 587Ah cells and to 6.26MWh with 588Ah cells. It utilises similar 104S1P packs like the ones in 5MWh, but they have 8 clusters instead of 12 clusters in the 5MWh BESS.

The 6.25MWh BESS requires the newly launched 3.15MW-rated PCS. This PCS configuration is just entering the market and is still undergoing certifications.

The 6.25MWh BESS uses a very modular approach to capacity sizing. It can be used in multiples of 4 nos. for every 25MWh project. For example, a 100MWh project would use 16 such containers instead of 20 5MWh BESS containers.

Similarly, 600Ah+ cells, such as 684Ah and other larger LFP prismatic cells, are not suitable for production on existing manufacturing lines and require new lines; they can only be produced via the lamination (Z stacking) process due to their larger size. Larger-sized cells are difficult to produce in the winding method.

The larger the cells become, the lower the manufacturing and raw material costs, but they have poor thermal management, so the C rate of use becomes a constraint. These cells are being introduced for 0.25C (4- hour) projects. They are not yet ready to be used for 0.5C projects, and it will take a while.

The use of 6.9MWh BESS is well-suited to work with existing 1.725MW PCS for 0.25C projects and can also be compatible with 2 nos. of 1.725MW PCS for 0.5C projects. 1.725MW PCS is an older design that has been in production for a while; it was launched to suit a 3.44MWh BESS (older than the 5MWh BESS design). 6.9MWh BESS can also replace the old projects that utilise 3.44MWh BESS and are due for capacity augmentation.

Additionally, some companies have launched 700Ah+, 800Ah+, 1000Ah+ and 2000Ah+ cells. They are all going into mass production soon. They are targeted to achieve 7MWh+ and 8MWh+ systems and higher capacities.

The race for larger cells will continue, and there is no limit to how big they can get. But this comes at a cost and requires constant investments for cell manufacturing companies and BESS assembly companies.

About the author

Rahul Bollini, Bollini Energy

Rahul is a seasoned technical expert in Lithium-ion cells, EV batteries and BESS, with over 11 years of experience in manufacturing facility setup, process development, and project execution. Based in Bangalore and Shenzhen, he provides technical leadership and end-to-end project support to companies across global markets. He can be reached at +91-7204957389; bollinienergy@gmail.com.

Also read: The rise of 587Ah cells and 6.25MWh battery energy storage system