Dear Stockholders,

Today, about 1,400 people work at G1_Dallas manufacturing American energy. These aren’t assembly-line jobs from the 1950s. We’re talking high‑tech, high‑skill work in robotics, precision engineering, materials science, and quality control. Jobs that pay well. Jobs that need problem solvers. Jobs that build careers.

This is advanced American manufacturing. Humans and advanced robotics, working together to keep one of the world’s most modern solar manufacturing facilities operating safely, efficiently, and profitably.

At T1, we build energy.

We’re operating a facility that produces thousands of solar modules daily. Tested, sorted, and packaged, we load them onto trucks for delivery to tomorrow’s solar farms. To power America’s energy future.

We believe the need for these modules has never been clearer. After years of stagnation, we are in a generational time of energy demand growth. According to the Department of Energy (DOE), in 2025, electricity demand in the U.S. rose 2.8% to a record 4,430 terawatthours, and the DOE expects that electricity generation will rise again in 2026 and 2027. We believe solar and storage are the only energy assets that can scale over the next few years to meet this rising demand.

The United States added 53 gigawatts of new generating capacity to our grids in 2025, the largest increase in more than two decades. We believe this is not ambitious enough. We believe we need to build faster. To accelerate American reindustrialization. To power hyperscalers and win the AI race. To bring advanced manufacturing back.

Last year, 79% of new electricity generation added to U.S. grids was solar and storage. This year is shaping up to be no different. According to data from the DOE, for the first three months of 2026, that figure rose to 88%.

We’ve come a long way fast. Solar and storage were only 15% of new electricity generation as recently as 2018.

In Q1 2026, 88% of new electricity generation added to U.S. grids was solar and storage.

Solar and storage offer a winning combination of scalable, reliable, and low-cost power. This is not about tax credits. All sources of energy benefit from a combination of tax credits, favorable accounting treatment, and grandfathered exemptions from construction codes. We are convinced that the U.S. has the people, skills, technology, and capital to deliver the entire solar value chain from raw polysilicon to solar farm in a cost- competitive manner to support a lasting energy solution.

We see that winning combination being recognized by the market in the U.S. and globally for two reasons. The first is cost. Solar is essentially zero-marginal cost electricity generation for decades. Add in capital costs and it is still a very cost-effective solution, according to Rystad Energy, which also reported that battery costs have also fallen remarkably in recent years. Solar delivers abundant, low-cost electricity; batteries store and shift gigawatts, making the combination both affordable and reliable. According to Rystad Energy, solar PV with battery storage has a levelized cost of energy of $68-133/megawatthour compared to U.S. natural gas of $64-125 and large-scale nuclear power of $177-347.

The second is speed. We believe that solar and storage offer one of the fastest, most scalable routes to electricity generation today and for the foreseeable future.

Technology used to govern energy growth. Today, energy governs AI growth.

For decades, advances in oil and gas production relied on breakthroughs in 3D seismic, hydraulic fracturing, combined cycle turbines, and advances in material science for deepwater drilling. Today, energy gatekeeps growth in technology. Without abundant energy, the contest for AI leadership may be lost.

Our mission is to build advanced, domestic solar manufacturing and supply chains in the United States.

In 2025, our first year as T1 Energy, we optimized operations at G1_Dallas, exceeding nameplate capacity. We manufactured 2.79 gigawatts and generated $755.3 million in net sales. Some may see this as a remarkable accomplishment for a new entrant into solar energy. We see it as a good start.

T1 Energy generated $755.3 million in total net sales for 2025.

We are committed to running G1 as safely, profitably, and efficiently as possible, combining a world-class workforce, robotics, and AI to supply abundant energy profitably.

To create a domestic supply of solar cells for our modules, our team began construction of our flagship U.S. solar cell fab, G2_Austin, in December. Construction on the first 2.1 gigawatt phase is progressing according to plan. And I’m happy to report that T1 remains on track to start cell production in the fourth quarter of 2026. When both phases of G2 are completed, bringing total capacity to a planned 5 gigawatts, we expect to support a workforce of up to 1,800 people.

Operating G1. Building G2. These are the building blocks of a company we intend to turn into a cashflow powerhouse. At T1, we are committed to generate value from these world-class assets.

Last year, we laid the foundation to become a new American solar champion. We expect 2026 to be a bridge year to vertical integration and we expect in 2027 to generate an annualized run rate of $375 million to $450 million in adjusted EBITDA once the first phase of G2 is fully ramped.

We believe there is significant commercial desire for an American manufacturer of high efficiency, competitively priced solar modules. Last year, we saw evidence of our thesis. We signed a long-term offtake deal with Treaty Oak Clean Energy for domestic modules with domestic cells—and completed merchant sales to several of the largest utility and developer customers.

While global module pricing remains competitive, we expect domestic content premiums and our roadmap to drive down costs and position us well.

Today, we’re offering what we believe is a new choice to the market. Customers can now purchase advanced solar modules from an American-owned facility in Texas. We offer domestic TOPCon modules that achieve 23% efficiency. Next year, we expect to offer domestic TOPCon modules with domestic TOPCon cells. We believe customers will continue to embrace the combination of high efficiency, low-cost modules that are manufactured in America.

Our guiding focus is investing in American advanced manufacturing to power our nation’s energy independence and bring cutting-edge technology capabilities back to the U.S. Manufacturing our electrons in the U.S. can assist in keeping energy affordable, helping ensures data centers have the scalable energy they need when and where they need it, supporting a U.S. polysilicon industry, and empowering the U.S.’s AI leadership.

We believe domestic solar manufacturing means the U.S. can continue to be the number one exporter of oil and natural gas while ensuring ample affordable power here at home. Last year, the U.S. exported more liquefied natural gas than any other country has, ever. Solar energy can free natural gas for export. America’s energy abundance (lots of both natural gas and solar farms) creates opportunities to keep energy and electricity prices low at home while also helping it continue to be a world-class energy exporter. In the U.S., solar and natural gas are working together to fortress America and keep energy insecurity far from our shores.

Solar is how energy abundance becomes durable and permanent. Manufacturing energy abundance with free sunlight is one way we can unlock the next era of American strength.

Domestic solar energy is energy security and energy security leads to economic prosperity. We are proud to play our our role in securing a bright future for the United States. Thank you for coming along on this journey.

Sincerely,

Daniel Barcelo Chief Executive Officer and Chairman of the Board

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This letter was filed with the SEC on May 18th, 2026. Access the full proxy statement on our Investor Relations page here.

Forward-Looking Statements

This letter contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements other than statements of historical or current facts contained in this letter are forward-looking statements, including statements regarding our future results and timing of operations, expected performance and financial position, business strategy and plans and objectives of management for future operations, including, among others, statements regarding our anticipated liquidity, growth and profitability strategies, expectations regarding demand for and market adoption of our products, the capabilities, performance and competitive advantage of our technology and products, the timing and anticipated benefits of our manufacturing facilities, and factors and trends affecting our business, including growth and other trends in the markets we serve, and expectations relating to amendment to increase the authorized share capital. Forward-looking statements can be identified in some cases by the use of words such as “believe,” “can,” “could,” “potential,” “plan,” “predict,” “goals,” “seek,” “should,” “may,” “may have,” “would,” “estimate,” “continue,” “anticipate,” “intend,” “expect,” or the negative of these words, other similar expressions or discussions of strategy, plans or intentions and are intended to identify forward-looking statements, although not all forward-looking statements contain such identifying words.

The forward-looking statements contained in this letter are only predictions. We base these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. Forward-looking statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements, or industry results, to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. We believe that these risks, uncertainties and other important factors include, without limitation, the risks set forth in Part I, Item 1A, “Risk Factors” of our Annual Report on Form 10-K for the year ended December 31, 2025, as amended and supplemented by Amendment No. 1 on Form 10-K/A, available on the SEC’s website at www.sec.gov, and in our other filings with the SEC, including risks related to: (1) our ability to (i) construct and equip manufacturing facilities in a timely and cost-effective manner; (ii) target and retain customers and suppliers; (iii) attract and retain key employees and qualified personnel; (iv) protect our intellectual property; (v) comply with legal and environmental regulations; (vi) compete in international markets in light of export and import controls; (vii) incur substantially more debt; (viii) remediate the material weakness in our internal control over financial reporting or otherwise maintain effective internal control over financial reporting; (ix) qualify for the advanced manufacturing production credit under Section 45X of the IRC; and (x) rely on third-party warranties; (2) the concentration of our operations in Texas and our dependence on a limited number of suppliers; (3) changes adversely affecting the flow of components and materials from international vendors, the costs of raw materials, components, equipment, and machinery; (4) general economic and geopolitical conditions; (5) changes in applicable laws or regulations, including environmental, export control and tax laws and incentives and renewable energy targets, as well as international trade policies, including tariffs, on our products and our competitive position; (6) the outcome of any legal proceedings relating to our products and services, including intellectual property or product liability claims, commercial or contractual disputes, warranty claims, and other proceedings; and (7) the capital-intensive nature of our business and our ability to raise additional capital on attractive terms or service our debt. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified, you should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based on information available to us as of the date of this letter and while we believe such information provides a reasonable basis for these statements, and our management is responsible for the accuracy of such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.

You should read this letter with the understanding that our actual future results, levels of activity, performance and achievements may be materially different from what we expect. All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by these cautionary statements.

These forward-looking statements speak only as of the date of this letter. Except as required by applicable law, we do not assume any obligation to update any forward-looking statement, whether as a result of any new information, future events or otherwise.