History of 10,000 cycles or 10 year warranty for Battery Energy Storage System (BESS)
Batteries have shorter asset life when compared to traditional T&D assets like transmission lines, or distribution feeders. However, that asset life is dependent on number of cycles per day.
Where did the 10-year warranty come from?
According to Rahul Walawalkar, a storage expert, the 10,000 cycle was mostly about Lithium Titanate (LTO) batteries.
But the 10-year warranty is for batteries with 3500 plus cycles. If we have 1 cycle per day, 350 cycles per year, it is 3500 cycles for 10 years. So, that’s the logic behind 10 year BESS warranty.
Source - OpenAI. (2024). ChatGPT [Large language model]. /g/g-pmuQfob8d-image-generator
T&D utilities always prefer traditional T&D solutions like transmission lines and distribution feeders.
Battery Energy Storage Systems (BESS) are here to stay. We know that because a lot of utilities are modeling BESS in their distribution (e.g., Integrated Distribution Plan, Distribution System Plan) and resource plans (e.g., Integrated Resource Plan). States like California are leading in storage implementation due to the capacity benefits.
When compared to a distribution asset life or a transmission asset life, BESS has a shorter asset life, the Transmission & Distribution (T&D) utilities claim in those distribution and resource plans.
What is BESS life dependent upon?
BESS life is dependent on 1) the number of cycles, 2) whether the cycle consists of moving from 20% to 70% or 30% to 70% of the full charge, 3) the battery chemistry (e.g., Lithium Iron Phosphate, Nickel Manganese Cobalt, Flow batteries) 4) temperature and I am sure I am missing some other variables here.
I found a World Bank report that mentions a 20-year warranty for BESS in developing countries. Read the report here - https://documents1.worldbank.org/curated/en/339531600374280939/pdf/Warranties-for-Battery-Energy-Storage-Systems-in-Developing-Countries.pdf
If we cycle less, the BESS Life is extended.
See the chart below from DNV, https://www.dnv.com/article/energy-storage-capacity-warranties-beyond-the-fine-print-200339
The DNV chart shows when the battery is cycled twice daily, then, the life is just around 16 years. On the other hand, when the battery is cycled only once per day, then, the life is more than 20 years.
Powin is offering 20 year-1 cycle warranty.
Here is an article that shows a 20-year-1cycle warranty offered by Powin.
https://www.energy-storage.news/catl-batteries-energise-powins-new-long-duration-long-life-li-ion-systems/
Shifting gears to the consumer energy storage market
Sonnen offers 10 years/10,000 cycles at 70% capacity and 15 years/15,000 cycles at 65% capacity. See Sonnen’s website here - https://sonnenusa.com/en/warranty/
Source - https://sonnenusa.com/en/sonnencoreplus/
Tesla is also offering 10-year warranty, see https://www.tesla.com/powerwall
NREL data shows BESS asset life is 15-20 years.
The National Renewable Energy Laboratory shows the BESS asset life ranges from 15-20 years.
Cole, Wesley and Akash Karmakar. 2023. Cost Projections for Utility-Scale Battery Storage: 2023 Update. Golden, CO: National Renewable Energy Laboratory. NREL/TP-6A40-85332. https://www.nrel.gov/docs/fy23osti/85332.pdf
DNV GL Battery Performance Scorecard is another resource.
In addition to NREL, DNV GL, a consulting company has a “Battery Performance Scorecard”, which you can download here - https://www.dnv.com/power-renewables/energy-storage/2022-battery-scorecard.html
Bottomline - Batteries have shorter asset life when compared to traditional T&D assets like transmission lines, or distribution feeders. However, that asset life is dependent on the number of cycles per day.