1 October 2026

Invinity Energy Systems plc

("Invinity" or the "Company")

California VFB Surpasses 1 GWh of Energy Delivered

10 MWh battery at Viejas Resort & Casino reaches major operating milestone, demonstrating strong real-world performance and high-throughput capability

Invinity Energy Systems plc (AIM: IES), a global leader in vanadium flow battery technology, is pleased to announce that its customer, Indian Energy, has now delivered more than 1 GWh of energy from their Invinity vanadium flow battery (“VFB”) system operating at the Viejas Enterprise Microgrid in California.

The VFB system was delivered on schedule and fully commissioned in late 2025 at the Viejas Casino & Resort near San Diego, California. Since entering commercial operation, the Invinity VFB has been used near-continually, charging from on-site solar generation and discharging electricity to support resort operations, delivering more than 1 GWh of stable, on-demand power to date. During this time, the battery has met or exceeded all contracted performance parameters.

The project, which received support from the California Energy Commission, features Invinity’s batteries coupled with a 15 MW solar array and is California’s largest tribal microgrid installation. The milestone adds to Invinity's growing operational track record and provides further evidence of the Company's ability to deliver, commission and support utility-scale vanadium flow battery projects in commercial operation.

Allen G. Cadreau, CEO at Indian Energy said:

“Surpassing 1 GWh of energy delivered is a significant milestone for the Viejas Enterprise Microgrid and demonstrates the value of vanadium flow battery technology operating in a demanding real-world environment. Invinity’s battery system has proven to be a true workhorse for us, consistently performing to specification and supporting our operational requirements since commissioning.

“Invinity's team has worked closely with us at every stage of this project. Their commitment to quality, transparency and customer support has been evident throughout, and we look forward to continuing our partnership on future projects."

David Hochschild, Chair at California Energy Commission said:

“The California Energy Commission has backed Invinity’s Vanadium Flow Battery technology through a series of grant-funded projects since 2021, reflecting the CEC’s commitment to advancing reliable, long-duration energy storage. This latest achievement at the Viejas Enterprise Microgrid, delivered by Indian Energy and Invinity, marks another important milestone in California’s journey toward a clean energy future.”

Matt Harper, President at Invinity said:

“Delivering more than 1 GWh of energy is an important milestone for both Indian Energy and Invinity and demonstrates the ability of our vanadium flow batteries to provide reliable, repeatable service in demanding commercial applications where customers rely on their energy storage assets every day.

"At Viejas, our system has consistently delivered against its performance commitments while helping maximise the value of onsite renewable generation. Milestones such as this provide powerful evidence of the maturity of our technology, the strength of our customer relationships and the growing operating track record which underpins our business."

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Notes to Editors

Invinity Energy Systems plc (AIM: IES) is a world-leading manufacturer of vanadium flow batteries for energy storage. Built in our factories in the UK and Canada, the Company's proven, commercialised, longer duration energy storage technology has been deployed at scale and dispatched gigawatt-hours of electricity for customers across the world.

Invinity's safe, scalable and durable battery technology is a trusted and safer alternative to lithium-ion batteries. Endurium VFBs are engineered for heavy-duty, high throughput applications, they don't wear out, cannot catch fire and are designed to be operated for 30 years or more. Our products address the challenges of our global energy system, unlocking the power of renewable generation by delivering energy storage without limits.

To find out more, visit invinity.com, sign up to our monthly Investor Newsletter here or contact Investor Relations on +44 (0)20 4551 0361 or [email protected].

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