Maria Telkes: She Stored the Sun, MIT Fired Her

Posted by by Female Obscura

She stored the sun’s heat. They wrote her out of the program.

In 1948, in Dover, Massachusetts, a house held its warmth through a New England winter with no furnace and no fuel. The heat came from the sun, caught by day and released at night by drums of a common industrial salt. Three women built it. The engineering was hers.

Her name was Maria Telkes.

The salt that held the sun

Telkes was born in Budapest on 12 December 1900 and took a doctorate in physical chemistry from the University of Budapest. She came to the United States in 1925, worked as a biophysicist at the Cleveland Clinic, then moved to Westinghouse. In 1939 she wrote to MIT asking for a job on its new solar program. She was hired.

She had one conviction and she never moved off it. Solar energy, she wrote, is “the greatest untapped energy resource of the world.” She spent the rest of her life proving it against men who told her it could not pay.

The problem she chose was storage. Sunlight is free and intermittent. To heat a house through the night and through a run of grey days, you have to hold the day’s heat somewhere. Water needed enormous tanks. Rock was worse. Telkes turned to phase-change materials, substances that absorb and release large amounts of heat as they melt and refreeze. She settled on Glauber’s salt, sodium sulfate, cheap and everywhere.

During the war she had already built a solar still that vaporised seawater into drinking water. It went into the emergency kits on military life rafts and kept downed airmen and torpedoed sailors alive. She held more than twenty patents before she was done. In 1952 she became the first person to receive the Society of Women Engineers Achievement Award.

The skeptic in charge

The MIT solar program was run by Hoyt Hottel, a chemical engineer made chairman of the solar committee at twenty-five. He did not believe in the thing he was paid to study. He called the field’s optimists “crank inventors” working with “little more mental equipment than a rosy optimism.” He treated the sun as an engineering problem that the numbers would always lose.

Telkes treated it as a mission. That was the fault line, and it held from the start.

When MIT tested her Glauber’s salt storage in a 1946 solar house, the salt stratified and the containers corroded and leaked. Hottel blamed Telkes for imprecise work. Telkes blamed Hottel’s graduate students for failing to run the experiment as specified. MIT’s own president, Karl Compton, took her side and told the committee to stop puttering with measurements and build a real house using her method.

Hottel did the opposite. He rejected the salt, and he removed Telkes from the solar energy fund entirely. She was reassigned to the metallurgy department to go back to thermocouples.

They built it without him

Telkes did not stop. She found the modernist architect Eleanor Raymond, who introduced her to the philanthropist Amelia Peabody, who paid for the house. Three women, no MIT, no Hottel. The Dover Sun House went up in 1948 with a south wall of solar collectors and 3,500 gallons of Glauber’s salt in metal drums.

It worked for two winters and drew 3,000 visitors. A cover story in one magazine called it a bigger scientific development than the atom bomb. It was, at that moment, the most publicised solar house in the world, and Telkes had built it after the institution running solar research had shown her the door.

The salt eventually stratified again and the drums corroded, as they had at MIT, and the system was pulled. That is the honest end of the machine. It does not touch what she had proved: that a house could be heated by stored sunlight, and that she was the one who made it stand up.

The record they wrote

In 1953 an MIT dean, George Harrison, reviewed why the solar fund had produced so little. His report leaned on Hottel’s account. It called Telkes a person of strong opinions “which she expresses forcibly,” said colleagues found it “impossible to agree with her,” and reached for phrases like “rather radical opinions” and “ultra-radical tendencies” about a Hungarian woman in the McCarthy years.

Historians who have read the file since name it for what it is. Sara Shreve reads the report as sexism, the assertiveness a woman needed to earn an engineering doctorate in 1920s Hungary recast as a defect. After the review, MIT fired her.

Hottel stayed. He ran MIT’s solar work for two more decades, built more experimental houses, and when he died in 1998 the New York Times called him “a leader in the development of alternative fuels.” The man who fought solar heating at every turn kept the institutional credit for it. The woman who believed in it and built it was moved to metallurgy and then let go.

She kept working anyway, at New York University, at the University of Delaware, where in 1971 she helped build Solar One, the first house to make both heat and electricity from the sun. The solar boom she predicted arrived after her. She was inducted into the National Inventors Hall of Fame in 2012, seventeen years after she died on 2 December 1995.

In 2026, American Public Television built a documentary around her and called her the Sun Queen. The title is affectionate and it is also late. The record that mattered, the one written at MIT while she was still there to read it, spent her out as a difficult woman with radical ideas. She was right, and it was filed against her.

The archive grows. The silence shrinks. Enter the archive.

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