Stem's PowerTrack™ EMS Selected for 100 MWh of Utility-Scale Energy Storage Projects in Germany

PowerTrack Serves as the Integrated Control Foundation Enabling Market Participation at the Kölsa Site

Stem, Inc. (NYSE:STEM), a global leader in AI-enabled clean energy software and services, today announced that its PowerTrack™ Energy Management System ("EMS") has been selected in collaboration with developer and EPC Everyray GmbH for two utility-scale battery energy storage system ("BESS") projects in Germany: a 90 MWh installation in Kölsa and a 10 MWh installation in Elsterwerda. The projects are owned and financed by UESA Group, which is also supplying key electrical infrastructure, including the transformer station, handover station, and medium-voltage switchgear.

The Kölsa asset is co-located with an existing photovoltaic ("PV") plant, while the Elsterwerda project is a standalone BESS installation. Together, the projects further expand Stem's presence in the German market and reinforce PowerTrack EMS's role as the control system for sophisticated, utility-scale storage deployments across Europe. Commercial operations are expected to commence in summer 2026.

"Our work with Everyray continues to demonstrate what's possible when control infrastructure, optimization strategy, and engineering execution are aligned from the outset," said Matt Tappin, President of Software at Stem. "As their portfolio grows in scale and sophistication, PowerTrack provides the operational backbone that enables consistent performance, regulatory compliance, and long-term asset value. We're proud to support their continued expansion in the German market."

PowerTrack EMS will serve as the primary control and management platform for the Kölsa BESS, leveraging Stem's edge-to-cloud architecture to deliver continuous controller uptime, seamless integration, and robust grid code compliance. The system is certified under VDE-AR-N 4110, 4120, and 4130, covering the full range of medium and high voltage grid connection requirements applicable to utility-scale storage and hybrid assets in Germany. In addition to providing the core EMS platform, Stem is delivering engineering integration support to ensure seamless interoperability between the BESS, external optimization systems, and grid infrastructure.

"Delivering reliable, market-responsive storage requires tight coordination between hardware, control systems, and optimization platforms," said Jochen Wolf, Co-Founder and Managing Director of Everyray GmbH. "Stem's technical depth and collaborative integration approach have been instrumental in delivering a robust, grid-compliant solution."

Everyray is deploying industry-leading solutions across the Kölsa site, including the optimization solution by Entrix, a market leader for trading flexible energy systems in Europe. The optimization solution will interface with PowerTrack EMS to execute AI-supported trading and ancillary services strategies. Stem's vendor-neutral architecture enables asset owners to maintain flexibility in optimization strategy while ensuring secure, high-performance plant-level control.

"Battery storage plays an increasingly important role in strengthening the energy system by providing flexible capacity and reliable system support," said Steffen Schülzchen, founder and CEO of Entrix. "Maximizing this value requires both technical excellence and sophisticated market execution. Through AI-powered optimization and 24/7 trading operations, we ensure that the Kölsa asset participates efficiently in Germany's ancillary services and wholesale markets. Working alongside Everyray and Stem, we are combining advanced trading strategies with dependable, real-time plant control to deliver sustained performance and reliable market execution."

The Kölsa and Elsterwerda deployments underscore Stem's expanding role in Europe's rapidly maturing storage market, where demand for scalable, vendor-neutral control architecture continues to grow alongside portfolio size and operational complexity.

For more information on Stem and the PowerTrack Suite, visit stem.com.

About Stem

Stem (NYSE:STEM) is a global leader reimagining technology to support the energy transition. We turn complexity into clarity and potential into performance.

Stem helps asset owners, operators, and energy stakeholders unlock the full value of their portfolios by enabling the intelligent development, deployment, and operation of clean energy assets. Stem's integrated software suite, PowerTrack™, is the industry-standard and best-in-class platform for asset monitoring and optimization and is backed by expert professional and managed services, all delivered under one roof. Designed to address complex energy challenges seamlessly, our technology transforms raw data into clear, actionable insights, providing the visibility and intelligence needed to drive performance. With projects across 55 countries, customers have trusted Stem for nearly 20 years to maximize the value of their clean energy investments.

Driven by human and artificial intelligence, Stem is unlocking energy intelligence. Learn more at stem.com.

About Everyray

Everyray is a developer and provider of comprehensive clean energy solutions, transforming energy systems from concept through commercialization to enable cost-effective adoption of utility-scale solar and battery storage. The company partners with clients to design, permit, build, and optimize tailored renewable energy assets that maximize operational performance and long-term value. With a focus on sustainable outcomes and rapid deployment, Everyray delivers end-to-end project support and solutions that help businesses and communities accelerate their clean energy objectives.

About UESA GmbH

UESA GmbH is an established German energy infrastructure company specializing in the development, manufacturing, and assembly of electrical systems for industrial, utility, and renewable energy applications. With more than 600 employees, the company delivers customer-focused solutions across energy distribution systems, cable distribution systems, transformer stations, low- and medium-voltage switchgear up to 36 kV, as well as automation, central control systems, and solar-related services. From initial concept development through production and logistics, UESA provides integrated system solutions supported by a broad technology portfolio and a strong partner network. In addition to its longstanding presence in Germany, UESA has expanded its production and sales activities internationally, with a particular focus on Poland.

About Entrix

Entrix is an energy trader and market leader for trading flexible energy systems in Europe. Beyond AI-powered trading, Entrix provides innovative solutions for long-term revenue security and grid-supportive battery operation. With our full-service package, we support clients throughout every project phase – from technical design and integration, to continuous optimization, all the way to 24/7 operational support. That includes adapting to changing market conditions and unlocking new revenue opportunities. With more than 2.8 GW and 8.1 GWh as well as 61 battery storage assets under contract, Entrix is active in Germany, Poland, Italy, Spain, and Portugal, with offices in Munich, Warsaw, Milan, and Madrid. Entrix has been pioneering battery optimization in Germany by managing one of the country's first large-scale storage projects – and is now the trusted partner of leading infrastructure players such as Encavis, MEAG (Munich Re), as well as a wide range of local utilities.

Forward-Looking Statements

This press release, as well as other statements we make, contains "forward-looking statements" within the meaning of the federal securities laws, which include any statements that are not historical facts. Such statements often contain words such as "expect," "may," "can," "believe," "predict," "plan," "potential," "projected," "projections," "forecast," "estimate," "intend," "anticipate," "ambition," "goal," "target," "think," "should," "could," "would," "will," "hope," "see," "likely," and other similar words. Forward-looking statements address matters that are, to varying degrees, uncertain, such as statements about our expansion in Berlin, the newly integrated PowerTrack suite and their expected benefit to customers, our business strategies and those of our customers; our ability to retain or upgrade current customers, and our ability to further penetrate existing markets or expand into new markets. Such forward-looking statements are subject to risks, uncertainties, and other factors that could cause actual results or outcomes to differ materially from those expressed or implied by such forward-looking statements, including but not limited to our inability to execute on, and achieve the expected benefits from our expansion in Berlin and the newly integrated PowerTrack suite, as well as our operational and strategic initiatives; including from our cost reduction, workforce reduction and restructuring efforts; our inability to successfully execute on our strategy; the effects of the One Big Beautiful Bill on our business and that of our customers; disruptions in sales, production, service or other business activities; general macroeconomic and business conditions in key regions of the world, including inflationary pressures, general economic slowdown or a recession, high interest rates, changes in monetary policy, changes in trade policies, including tariffs or other trade restrictions or the threat of such actions, and instability in financial institutions; the direct and indirect effects of widespread health emergencies on our workforce, operations, financial results and cash flows; geopolitical instability, such as the armed conflicts between Russia and Ukraine and in the Gaza Strip and nearby areas; the results of operations and financial condition of our customers; pricing pressures; severe weather and seasonal factors; our inability to continue to grow and manage our growth effectively; our inability to attract and retain qualified employees and key personnel; our inability to comply with, and the effect on our business of, evolving legal standards and regulations, including those concerning data protection, consumer privacy, sustainability, and evolving labor standards; risks relating to the development and performance of our software-enabled services; our inability to retain or upgrade current customers, further penetrate existing markets or expand into new markets; the risk that our business, financial condition and results of operations may be adversely affected by other political, economic, business and competitive factors; and other risks and uncertainties discussed in this release and in our most recent Forms 10-K, 10-Q and 8-K led with or furnished to the SEC. If one or more of these or other risks or uncertainties materialize (or the consequences of any such development changes), or should our underlying assumptions prove incorrect, our actual results or outcomes, or the timing of these results or outcomes, may vary materially from those reflected in our forward-looking statements. Forward-looking statements and other statements in this release regarding our environmental, social, and other sustainability plans and goals are not an indication that these statements are necessarily material to the Company, investors, or other stakeholders, or required to be disclosed in our lings under U.S. securities laws or any other laws or requirements applicable to the Company. In addition, historical, current, and forward-looking environmental, social, and sustainability-related statements may be based on standards for measuring progress that are still developing, internal controls and processes that continue to evolve, and assumptions that are subject to change in the future. Forward-looking statements in this press release are made as of the date of this release, and the Company disclaims any intention or obligation to update publicly or revise such forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by law.

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