Exowatt is a next-generation renewable energy company offering customers a modular full-stack energy solution that can provide dispatchable power for up to 24 hours per day. Their flagship product, the Exowatt P3, stores solar energy as heat in a long-duration battery and converts it into electricity on demand. The solution is specifically designed to meet the needs of energy-intensive applications such as data centers. 

Pulse 2.0 interviewed Exowatt’s Co-Founder and CEO Hannan Happi to learn more about the company.

Hannan Happi’s Background

What is Hannan Happi’s background? 

Happi said: “I’m a mechanical engineer by training. I studied in Germany, where I worked at Siemens on combined cycle power plant design and later at General Electric on wind turbines. Thirteen years ago, I moved to the United States to join Tesla, working on the original Model S at the Fremont factory.

In 2015, I co-founded my first company alongside two co-founders from Stanford: a vertical take-off and landing drone startup for enterprise and military applications. We went through Y Combinator’s 2017 batch, attracted backing from Lightspeed and other incredible investors, and ultimately sold the company to a major defense partner. 

I later moved to Miami by invitation from Jack Abraham, founder of Atomic, and have spent the last couple of years working on Exowatt. We’ve seen tremendous demand for the product, and our team is moving quickly to serve our customers.”

Formation Of The Company

How did the idea for the company come together? Happi shared:

“When I teamed up with Jack Abraham in late 2022, our goal was to meet the soaring energy demands of AI data centers by tackling the intermittency of renewables. We quickly recognized that a modular, scalable design was essential for driving down costs through true economies of scale, and our unwavering focus on unit economics meant we sometimes sacrificed efficiency for affordability and growth.

Recognizing that traditional solar and wind systems depend on expensive electrochemical batteries for storage, we knew a full-stack solution integrating generation with low-cost storage was necessary. This insight led us to launch Exowatt with a simple yet ambitious mission: to make renewable energy always available and almost free. Although we serve multiple sectors, we see AI data centers as a major energy consumer and a prime opportunity to boost global competitiveness.”

Favorite Memory

What has been your favorite memory working for the company so far? Happi reflected:

“There are so many great memories, with the amazing team we have built but one that comes to mind was in the early days of our product development. We held a team building event where we were able to use optical lenses from the product to grill steaks for the team cookout. The team has grown significantly since those early days, so it was a chance for our early team to bond and reflect on the great work that the team had been doing. As we grow, I continue to make it a focus for the team to find ways to connect through offsites, happy hours, and other events. We have to rely on each other day in and day out,  operate as a collective, so whatever we can do to grow closer, we do it.”

Core Products

What are the company’s core products and features? Happi explained:

“Our flagship product is the Exowatt’s P3, a three-in-one system that generates, stores, and dispatches electricity up to 24 hours a day. It harnesses solar energy, storing it as heat in a long-duration thermal battery cell, then uses a heat engine to convert that heat into electricity on demand.

Storing energy as heat is nearly 200 times cheaper than using lithium-ion batteries, which is why our focus is on thermal storage. Our battery cell is engineered without phase change materials, chemical or electrochemical reactions, moving parts, or electric current—resulting in minimal degradation and lower overall losses.

Additionally, the modular design of the P3 allows operators to easily scale projects. More engines can be added for increased power output, or more battery cells can be integrated for additional dispatchable energy, ensuring true linear scalability for projects of any size.”

Challenges Faced

Have you faced any challenges in your sector of work recently? Happi acknowledged:

“The reality is that our main challenge is in scaling up our manufacturing to meet the significant demand that we’ve garnered to date. We’ve recently hired an industry veteran to be the Head of Supply Chain and Manufacturing and have partnered with leading contract manufacturers to build out the needed scale in the coming years. But we have lofty goals and a ton of demand so we’re focused on moving quickly to meet the speed to power needs of our customers.”

Evolution Of The Company’s Technology

How has the company’s technology evolved since launching? Happi noted:

“We’re continuously evolving our product. We’ve gone through over 50 iterations of the product to land on our current product. Through this process, we’ve decreased our bill of materials significantly to continue to drive down costs. We’re gearing up to ship our first products to customers in 2025 but continuing to do R&D with a focus on unit economics and scalability.”

Significant Milestones

What have been some of the company’s most significant milestones? Happi cited:

“One of the biggest milestones to date has been the immense backlog of capacity reservations we’ve been able to secure. It’s currently around 85GWh and growing. This includes hyperscalers, data centers developers, and renewable energy developers . This is a testament to the need for a solution like ours but it’s also a mandate for our team to execute. We intend to do just that.”

Customer Success Stories

Can you share any specific customer success stories? Happi highlighted:

“We’re launching commercially with our first pilot customers later this year. Our early customers are looking to utilize our modules to produce onsite renewable energy or to pair our modules with intermittent energy resources such as solar PV to better optimize their system and create quasi baseload solutions – think 6-8 hours of solar PV and 16+ hours of Exowatt P3.”

Funding

When asking Happi about the company’s funding details, he revealed:

“We completed our $20 million Seed round in April of last year. It was led by a16z, Atomic, and Sam Altman. We can’t thank our investors enough. Their support has helped us to scale our team and our operations immensely.”

Total Addressable Market

What total addressable market (TAM) size is the company pursuing? Happi assessed:

“Our data center TAM in North America alone is greater than $100 billion and growing and we’re well positioned to capture a large share.”

Differentiation From The Competition

What differentiates the company from its competition? Happi affirmed:

“While the cost of generating renewable energy has significantly decreased, Exowatt’s P3 system stands out because it doesn’t simply store or pass along energy produced elsewhere. Instead, it can generate, store, and supply power all in one solution. This approach provides a steady flow of power over long periods, even when sunlight and wind are unavailable.

In contrast, many battery systems (especially lithium-ion) are limited to shorter dispatch durations and degrade over their lifespan. Exowatt’s technology can deliver power for longer stretches, covering a significant portion of commercial and industrial customers’ baseload needs. This is particularly beneficial for large energy users such as data centers, which cannot always wait for other emerging solutions like nuclear or geothermal that can take years to develop and get online.” 

Future Company Goals

What are some of the company’s future company goals? Happi emphasized:

“We’re here to power ‘World 3.0,’ where innovation increases affordability and equity. What we mean by “World 3.0” is this new world in front of us that has advanced technologies such as artificial intelligence, robotics, flying cars, and biotechnologies that will cure cancer. We want to power all the emerging technologies that will make the world better using low-cost, sustainable, renewable energy. For instance, if AI is going to consume a full quarter of all power in the U.S. by the end of the decade, we need the Exowatt P3 scaling with data center growth.”