Exowatt is revolutionizing the energy landscape for the AI era with our groundbreaking P3 system that captures solar energy, stores it as heat, and generates electricity on demand. Founded in 2023 and backed by leading investors including Andreessen Horowitz, Sam Altman, and Felicis, we're committed to providing clean, modular, and scalable power that meets the rapidly growing demands of AI infrastructure. Our mission is to make sustainable renewable energy always available and almost free, enabling technological advancement while protecting our planet. The receiver is where sunlight becomes stored heat, and it sets how much of the sun’s energy reaches the battery. As our Lead Thermal Design Engineer, you’ll own the component that absorbs concentrated sunlight from our Fresnel optics and moves that heat into the thermal battery. That includes the receiver, absorber and heat exchanger. This is not a one-off tower project. Your design will be built thousands of times on a production line, so every point of efficiency and every dollar of cost compounds across every module we ship. This position is based in Austin, TX. If hired for this role, relocation to Austin, TX is required. We provide relocation assistance. \n What you’ll do • Own the receiver end to end. That covers architecture, design, analysis, prototyping and qualification, with direct influence on system cost and performance targets. • Set the technical direction. Define requirements, run design reviews and make the architecture trade-offs that decide how much of the sun we capture and keep. • Build fast, validated models. Model optics, flux distribution, heat transfer and thermal stress, and use them to iterate designs in days, not quarters. • Pick materials that survive. Select and qualify ceramics, refractory metals and advanced alloys that hold up at 600–1,000°C+, through daily thermal cycling and under concentrated flux, for 30 years. • Test on real hardware under real sun. Run high-flux prototype tests and accelerated life testing on hardware, not just in simulation. • Design the system as one. Work closely with the optics, thermal storage, heat engine and controls teams on lens focal geometry, tracking, flux uniformity and integration. • Build for manufacturing from day one. Work with our Austin manufacturing team so the receiver scales from prototype to high-volume production at a cost that supports 1¢/kWh. • Shape the roadmap and the team. Bring in advances in selective absorbers, high-temperature coatings and receiver design, and grow the team around you as we scale. What you bring • Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, Materials Science or a related field, or equivalent engineering depth. • 7+ years designing high-temperature thermal hardware, such as solar receivers, heat exchangers, combustors, furnaces, propulsion components or other systems that run at extreme heat flux. • Deep command of heat transfer (conduction, convection, radiation), thermodynamics and fluid mechanics, and the judgment to know when a hand calculation beats a week of simulation. • Strong skills with thermal and structural simulation tools (ANSYS, COMSOL or equivalent), backed by physical intuition. • Hands-on experience selecting, qualifying and analyzing failures in high-temperature materials. • A track record of taking hardware from concept through prototype testing into production. Bonus points • MS or PhD in a relevant field. • Direct experience designing solar thermal receivers or concentrated-solar hardware. • Optical modeling and ray tracing for flux analysis (SolTrace, Tonatiuh, Zemax, LightTools or equivalent), especially with refractive or Fresnel optics. • Experience with solid-media or packed-bed thermal storage, or gas-to-solid heat transfer. • Knowledge of selective absorber coatings and high-temperature surface treatments. • Experience designing high-volume, cost-driven hardware, such as automotive, aerospace production or appliances. • Publications or patents in solar thermal or high-temperature heat transfer. • You do well in an early-stage hardware company where you set the standard rather than follow one. \n $165 - $215 a year \n What We Offer: Competitive salary and equity options. Comprehensive benefits package, including health, dental, and retirement plans. A dynamic work environment that fosters creativity and innovation. Opportunities for professional growth and development in a rapidly evolving industry. Relocation assistance.