Why Modular Flow Batteries Might Be the Key to Clean Energy Scaling
A look inside how Invinity is using productized storage tech and deployment data to reshape grid reliability.
Solar Can Be Built in Weeks. So Why Does Storage Take Years?
When Matt Harper first started working on vanadium flow batteries in North America in the mid-2000s, installing a system could take more than two years. That pace of install was sufficient to match demand back then, but by the 2010s vanadium flow was at the risk of failing to keep up with renewable generation development. “We just knew there wasn’t going to be a fit between those two solutions,” Harper said.
That disconnect drove Harper and his colleagues to redesign the technology from the ground up — resulting in a plug-and-play, fully modular flow battery that ships factory-tested and deployment-ready. “We asked ourselves: could we take the fundamentals of that vanadium flow battery technology and turn it into something that was totally modular… ready to be plugged in and switched on immediately off the back of a truck?” The most recent outcome of this innovation is their next-gen ENDURIUM™ modular vanadium flow battery for long-duration, high-throughput, large-scale energy storage projects (https://invinity.com/introducing-endurium-transforming-grid-scale-energy-storage/).
Today, Harper serves as President and Co-Founder at Invinity Energy Systems , a company formed as a result of a 2020 merger between Avalon Battery and RedT Energy. With over 1,200 flow battery units in operation globally, Invinity now leads the world in deployed flow battery fleet size — and has the operational data to show for it.
That’s exactly why we brought Harper on the Beyond Lithium podcast.
In Episode 19, he joined host Nate Kirchhofer to unpack the strategic and technical lessons Invinity has learned on the front lines of energy storage deployment.
Here are 5 takeaways from the episode that energy storage developers and grid stakeholders can use to accelerate deployments and design smarter systems:
1. If a battery takes years to deploy, it’s already obsolete.
Harper made it clear that traditional on-site construction of flow batteries simply wasn’t compatible with the speed of renewable energy expansion. “Vanadium flow batteries were taking 2 to 2.5 years of on-site construction,” he said. “But solar plants were being built out at the rate of 10s of megawatts per week.”
The answer was modularity. By redesigning the battery as a shippable, pre-tested system, Invinity brought deployment timelines in line with the pace of modern solar and wind development. Today, their batteries can be dropped in and connected without the need for complex site assembly.
2. A large operational fleet = smarter next-gen design.
Every Invinity battery module in the field is fully instrumented and transmits operational data back to headquarters. “That data set — from what is now a deployed fleet of over 1,200 — is an incredible advantage,” Harper noted.
No other flow battery manufacturer comes close in deployment scale, which gives Invinity a unique feedback loop for refining both product performance and manufacturing efficiency. “The ability to look at how those are really performing in the field over time … has been used to continually improve the performance, design, and ultimately cost of the product,” Harper added. This learning rate is also a boon for the flow battery industry at large.
3. Intraday storage (10–36 hours) is the grid’s unsung hero.
There’s a lot of hype around seasonal and ultra-long-duration energy storage, but Harper pointed to intraday storage — the 10–36 hour window — as the segment that will “do the heavy lifting of long duration storage in the electric grid.”
He cited the U.S. Department of Energy’s Pathways to Commercial Liftoff report, which highlights this category as crucial for balancing variable renewables like wind and solar. “It’s intuitively obvious,” Harper said. “If you think about where the majority of renewable power is coming from… it varies on a daily basis. So storage technologies designed around that … are going to be the most useful.”
4. Permitting and interconnection still hinge on local people.
Even the best technology can hit roadblocks on the ground. Invinity has seen projects sail through approvals — and others get stuck for months. “We’ve had sites that have gone in very quickly and smoothly,” Harper said, “and we’ve had sites bogged down in paperwork chaos for months to years.”
His advice: work with local partners who know the permitting landscape. “People who’ve installed batteries in a particular jurisdiction… and who know where the local fire marshal just doesn’t like batteries, no matter what — they make all the difference.”
5. Next-gen ENDURIUM™ hardware (formerly Mistral) is designed for wind’s extreme duty cycles, and the intermittency of solar
Invinity’s most recent product, ENDURIUM™ (codenamed Mistral in the episode), was co-developed with Siemens Gamesa to meet the demanding requirements of wind energy. “Regulating output from wind turbines is a very punishing duty cycle,” Harper explained. “You’ve got to regulate power and voltage on a second-by-second basis, while also absorbing energy in the early morning and delivering it 8–12 hours later.”
The new system consolidates six modules into a single containerized unit with 75 kW / 300 kWh capacity — achieving greater energy density, easier deployment, and better economics. “We’re now benchmarking at about 38 square meters per megawatt-hour,” Harper noted. “That’s very competitive with the best of what else we see out there.”
Catch the full episode at the link below:
https://open.spotify.com/episode/6ASJGGP7TivaeRGsn6uxWU?si=5ef6c9ba5a1547fb
