Exowatt

Exowatt is an American renewable energy company based in Miami, Florida, founded in 2023 by Hannan Happi and Jack Abraham. The company designs modular thermal energy storage systems aimed at providing dispatchable renewable power, primarily targeting data centers and other energy intensive commercial applications.

Exowatt's product is the Exowatt P3, a modular solar thermal energy system that provides up to 24 hours of dispatchable power daily. The system captures solar energy using specialized lenses, stores it as heat in a long duration thermal battery, and converts it to electricity on demand using a heat engine. As of April 2025, Exowatt had raised $90 million in venture capital funding.

Corporate history

Exowatt was founded in 2023 by Hannan Happi (CEO) and Jack Abraham (Chairman). Happi's background includes roles at Siemens, General Electric, and Tesla, while Abraham is also the CEO of venture studio Atomic, where Exowatt was incubated, and co-founder of other companies including Hims & Hers Health and OpenStore.

The company was created in response to growing energy demands from artificial intelligence and data centers, with the founders identifying a gap in the market for renewable energy solutions that could provide reliable baseload power. According to Happi, the company underwent multiple design iterations before settling on its thermal storage approach, with more than 50 different versions of the technology considered during early development.

The company emerged from stealth mode in April 2024, announcing a $20 million Seed funding round led by Andreessen Horowitz (a16z), Atomic, and OpenAI CEO Sam Altman. The initial funding was directed toward developing the company's modular energy platform and establishing early customer relationships. According to Katherine Boyle, General Partner at a16z, cited the company's focus on U.S. manufacturing and energy infrastructure resilience as key factors in the investment decision.

In September 2024, Exowatt publicly unveiled its P3 product at the RE+ clean energy conference in Anaheim, California. The event featured attendance by several of the company's investors, including actor Leonardo DiCaprio. By late 2024, the company reported a customer backlog exceeding 85 GWh.

In April 2025, Exowatt announced a $70 million Series A funding round led by Felicis Ventures, bringing total funding to $90 million. The Series A included $35 million in equity and $35 million in debt financing provided by HSBC Innovation Banking and other partners. Additional investors across both funding rounds included 8090 Industries, Starwood Capital, MCJ Collective, MVP Ventures, GOAT VC, StepStone Group, Climate Capital, Overmatch Ventures, Protagonist, and actor Leonardo DiCaprio. The company indicated that this funding would support commercial deployments scheduled to begin in 2025.

Technology

The Exowatt P3 system operates as a modular energy unit designed to fit within a standard 40 foot shipping container footprint. It functions as a 3-in-1 system: capturing solar energy, storing it, and dispatching electricity on demand.

Solar collection

Unlike traditional photovoltaic (PV) panels that convert sunlight directly to electricity, the P3 uses specialized lenses to concentrate sunlight and convert it to heat. The system employs principles similar to concentrated solar power (CSP) but with adaptations for modularity and scalability.

According to Canary Media, the system uses "vintage tech" including Fresnel lenses, which help concentrate sunlight to achieve the high temperatures needed for efficient energy conversion.

Thermal storage

The captured solar energy is stored in a thermal battery system. According to Carbon Credits, this storage medium consists of materials like clay or ceramic composites designed to maintain stable performance without phase changes or chemical reactions.

The company emphasizes that its storage approach differs from molten salt storage used in many traditional CSP plants and from phase-change materials used in some other thermal storage systems.

According to Exowatt's website, the company claims that this thermal storage approach allows for energy storage with simpler materials and lower costs compared to electrochemical batteries. The company claims its thermal storage technology has minimal degradation over time compared to lithium-ion batteries that typically lose capacity after a certain number of charge cycles.

Power generation

The stored heat is converted back into electricity using a heat engine, which Latitude Media identifies as likely being a Stirling engine. This system allows for dispatchable power generation that can operate independently of sunlight availability.

According to Exowatt's materials, this approach enables energy storage without reliance on rare earth minerals or complex foreign supply chains, which differentiates it from many lithium-ion battery systems. The company's website states that their system includes power electronics and control systems to integrate with existing electrical infrastructure.

As of September 2024, Exowatt reported an initial electricity generation cost of just under $0.04 per kWh, with a long term target of achieving $0.01 per kWh or less, according to Mercom Capital Group's coverage. The company emphasizes its commitment to U.S-based manufacturing using domestically sourced raw materials.

Market focus and industry context

Exowatt primarily targets the energy needs of artificial intelligence-driven data centers, as well as other commercial and industrial (C&I) applications with high power demands, according to the company's website. The company positions its technology as addressing the growing energy requirements of computing infrastructure, particularly for AI applications.

Data center industry dynamics

According to pv magazine, Data center energy consumption could increase significantly in coming years due to AI deployment, creating demand for reliable power sources. Traditional data centers typically operate with strict reliability requirements, as noted by Capacity Media in its coverage of Exowatt.

Multiple sources report that data centers face power constraints in many regions, with pv magazine noting growing interest in behind-the-meter generation and storage solutions among technology companies seeking to reduce carbon emissions while ensuring reliable power.

Market positioning

The company has reported customer interest, with claimed backlog figures growing from over 500 MW in April 2024 to over 1.2 GW by September 2024, later described as 85 GWh in late 2024 and over 90 GWh by April 2025, according to the company's press releases and media coverage. These commitments reportedly come from data centers, energy developers, and hyperscalers across the United States.

According to Carbon Credits, Exowatt was planning an initial deployment for a West Texas facility supporting cryptocurrency mining operations.

Exowatt positions its technology as complementary to other renewable energy solutions. The company has been compared to other thermal battery startups such as Antora Energy and Rondo Energy, though with different technical approaches, as noted in the Carbon Credits article.

In industry analyses, Canary Media described Exowatt's approach as "repurposing vintage tech" like Fresnel lenses and thermal batteries (which they termed "hot bricks"), providing context on the technology's approach. MCJ Collective, an investor in the company, has highlighted the potential for 24-hour renewable energy availability.

Latitude Media published an analysis of the technology that raised questions about its scalability, including land use requirements and geographical limitations. The publication also noted that much of the company's reported backlog consists of preliminary agreements rather than firm orders.

Business model

Exowatt's business approach focuses on selling integrated hardware and software solutions directly to customers in energy-intensive industries, including energy developers and data center developers.

The company's manufacturing strategy emphasizes domestic production and sourcing, as highlighted in their press releases. This approach is mentioned by Katherine Boyle of Andreessen Horowitz as aligning with national infrastructure resilience goals.

See also

• Solar energy
• Concentrated solar power
• Thermal energy storage
• Data center
• Environmental impact of artificial intelligence
• Dispatchable generation