U.S. Patent 2,677,367 for a “Heat Storage Unit” is granted to Maria Telkes.
On 4 May 1954, Mária Telkes secured U.S. Patent No. 2,677,367 for a “Heat Storage Unit”, a key step in her quest to make solar energy reliable by storing heat for later use. The unit was designed to absorb thermal energy when available and release it when needed, smoothing out the intermittent nature of sunlight.
Telkes’s design employed materials and configurations that allowed for efficient heat absorption and retention, drawing on her expertise in physical chemistry and phase‑change materials. At mid‑century, one of the central challenges in solar engineering was how to bridge day‑night and seasonal gaps; this patent directly addressed that problem.
The historical significance of this patent lies in its contribution to the emerging field of thermal energy storage. By formalizing a practical heat‑storage unit, Telkes showed that solar‑based systems could approach the reliability of conventional fuels, provided that storage was engineered thoughtfully. As a woman inventor filing multiple patents in the 1950s, she defied prevailing norms that largely relegated women to subordinate technical roles. Her work on heat storage became foundational for later developments in solar‑heated buildings, solar power plants, and modern energy‑storage solutions that aim to decarbonize heating and power sectors.