The Energy Storage Report 2024

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Highly technical subject of battery analytics is ‘now something for the CFO to think about’


Kai-Philipp Kairies, CEO of analytics firm ACCURE, discusses some of the areas in which battery analytics can have the most impact on battery energy storage system (BESS) project success.

Kairies says that while analytics may previously have been considered the domain of the more technical members of a battery storage project team, their impact on the bottom line means it’s increasingly “a topic for the CFO”. As told to Premium, in conversation with editor Andy Colthorpe.

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Cloud-based battery analytics. Even if you have not come across this software-based solution to gaining better understanding of batteries in your work, you will likely have seen articles or webinars on the subject, including ours here at

We speak to Kai-Philipp Kairies from ACCURE, one of the growing number of cloud-based battery analytics vendors and service providers. ACCURE started as a spin-out from RWTH Aachen University’s battery practice.

Like its rivals, which in Europe include fellow German company TWAICE and PowerUp from France, ACCURE’s software is also used for electric vehicle (EV) batteries, but as Kairies says, its role in stationary BESS is growing rapidly.

The company went from ten managed sites to 40 in the 12 months leading to our interview at February’s Energy Storage Summit EU in London, UK, with each over 10MWh and the largest at 200MWh, across various markets, the CEO claims.

Last year, Kairies contributed the article: ‘Using battery analytics to support BESS commissioning: A technical deep dive,’ which ran in Vol.35 of our journal PV Tech Power, alongside the companion piece, ‘Cloud-based analytics for de-risking BESS deployment and operation‘ from Dr Stephan Rohr, Sebastian Becker and Dr Matthias Simolka at TWAICE.

Below, we take a more informal look at the role of analytics at different stages of the BESS development and life cycles.

Commissioning delays

“A lot of sites have seen quite relevant delays [in commissioning]. In our portfolio, we see three to four months delays, on average, with some sites having substantially longer delays. Analytics can drastically reduce that.

Obviously if you’re delayed because the transformer isn’t delivered, that’s something else. But if you can’t get site acceptance because the capacity isn’t provided [or] because of imbalancing, or maybe some of the modules were not correctly installed, it’s very difficult to figure out what exactly is the problem.

Analytics can give you the answer in a week, versus running across the site in circles, trying to figure it out. That’s what some of our partners did before contracting us.

One project that I can talk publicly about [that] I think is a nice example is National Grid Renewables in the US. They contracted us for commissioning support, because they were delayed on commissioning with their site.

It was really such a nice demonstration of how analytics can help because the timeline that they were looking at, it was already late and then they thought, ‘It’s going to take another two or three months.’ Using analytics it was weeks. So they were very positively surprised of how much we could help.

National Grid Renewables also contracted us for continuous monitoring afterward, for their entire fleet. Once you can show the value of analytics in one small thing, it really opens up the mind for everyone to say, ‘Oh, we could use that in other ways as well, like for the lifetime of an asset’.”

State of Charge assessment

“More and more companies are becoming aware of State of Charge (SOC) problems. Everyone’s using LFP lithium iron phosphate batteries now and as long as you’re making your money on highly contracted revenue stacks, perhaps frequency response, an error in the State of Charge estimation wasn’t that bad, but if you’re going into fully merchant or taking more merchant risks, it becomes very important how to dispatch your system. And if you’re operating on assumptions that are flawed, you’re not making the full revenue.

More and more people, as they move towards more merchant risk, become aware of technical problems that have been around for some time, but they weren’t relevant [previously]. Now they become more relevant and they need solving. And again, analytics can really improve that, we have demonstrated that with sites [of capacity] above 100MWh, we can improve the tradeable capacity by 5-10%.

This is really relevant on the revenue side. Analytics, in the beginning, has been more of a technical topic that engineering departments were interested in, but now it really becomes a topic for the CFO.”

Warranties and Long-term Service Agreements (LTSAs)

“More and more companies have complex setups for their traders. So, they might have two different traders, or they might think about getting trading [capabilities] in-house.

Now the question is, how does the trading affect the warranties? Does it violate some of the LTSAs? Do you lose your warranty because a trader made the wrong decision? How do you track that?

Again, analytics is just an information layer to help owners and operators make informed decisions, while right now a lot of them are flying blind.”

From factory to field deployment

“When I give talks these days, I always start with a small Pop Quiz.

Which percentage of batteries produced today come from factories that are less than two years old? The answer is: more than half. Over 50% of the batteries being produced today come from immature production lines.

Young production lines tend to have a larger spread in the output quality, and of that spread, some of the batteries go to scrap. You can’t just throw away 70% of your production, so they kind of pre-test it, batch it together and sell them at different price points.

Very good ones go into the Triple-A bucket and then the so-so ones. This is one of the reasons why commissioning sometimes has problems with site acceptance. Multiple batches of a production go to the same site and then you have some cells that are quite good, and some cells that are mediocre.

Which in itself is not a problem, but if they’re mixed, the mediocre cells will always limit the great ones. It’s like with solar, like the worst panel in the string will limit the string. With batteries, one mediocre module is enough to limit the capacity of an entire container, and that leads to huge problems.

Sometimes you can even get through site acceptance, you’re successful with all the tests, and then the owner-operator doesn’t even find out that some of these cells will have a much stronger degradation in the long term.

Then after three or four years, it becomes much more difficult to claim quality defects, versus on Day One. Three or four years down the line, the OEM might say: ‘Oh, you abused it, and let’s look at all the data. Maybe you did this one small thing that kind of voids the warranty.’

If you can do it on Day Zero, [you have] much more leverage.

We can provide these insights that are not available without analytics right now. The standard approach for site acceptance testing, or just looking at the voltage value, checking that’s within the range, it doesn’t give you the answer. Analytics can do really deep modeling that tells you the internal resistance spread is 20%, and it should only be 10%, and so on.”’ publisher Solar Media will host the 6th Energy Storage Summit USA, 19-20 March 2024 in Austin, Texas. Featuring a packed programme of panels, presentations and fireside chats from industry leaders focusing on accelerating the market for energy storage across the country. For more information, go to the website.

28 March 2024
8am (PDT) / 11am (EDT) / 4pm (CET)
This webinar provides invaluable insights into the challenges, risks, and solutions associated with battery energy storage systems. Participants will gain a deeper understanding of the importance of proactive monitoring, maintenance, and the role of battery analytics in optimising BESS performance and ensuring regulatory compliance. Additionally, attendees will learn about industry best practices and emerging trends in BESS management, enhancing their ability to effectively deploy and operate BESS infrastructure.

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