The sun house that ran out of salt
In 1948 a house in Dover, Massachusetts, was heated by sunlight stored in 21 tons of salt. It worked for about two and a half winters. Why its failure is worth remembering.
Leafhouse’s first operating principle is to document before advocating. The Dover Sun House is a good place to practise it, because its most useful lesson is the part that went wrong.
Three women and a wedge-shaped house
The house was built in 1948 in Dover, Massachusetts, on land owned by the Boston sculptor and philanthropist Amelia Peabody, who paid for it. MIT Technology Review puts the cost at about $20,000. The architect was Eleanor Raymond. The heating system was designed by Mária Telkes, a physicist then doing research at MIT.
At the time it was described as the only existing house heated solely by the sun. Its south wall carried 18 windows. Collectors warmed air, and fans moved that air to storage bins built into the walls.
Storing a week of sunshine
The clever part was the storage. Telkes filled the bins with 21 tons of Glauber’s salt, sodium sulfate decahydrate, which melts at about 90 °F. On sunny days the salt melted and absorbed heat. On cold nights and cloudy days it recrystallized and gave that heat back.
Telkes sized it from weather records. National Weather Bureau data showed Boston had not gone more than nine days without sun in 65 years, so she designed the store to carry the house through a ten-day sunless spell.
What failed
It ran on sunshine alone for about two and a half winters, by MIT Technology Review’s account. Then two problems compounded. The salt separated into layers that would not remix, so less of it melted and froze each day. And some bins corroded and leaked. In the third winter the system failed. The owners removed it, and in 1954 an oil furnace replaced it.
What it still teaches
The idea was sound. Phase-change storage packs more heat into less space than water or stone, and it is studied and used today. What failed was the material over time: a salt that would not stay mixed, in containers that did not survive it.
That is the pattern to watch for in any new building system. A prototype proves the physics. Only years of use prove the materials. Neither Telkes nor Raymond built another solar house, but Telkes went on to found a solar-energy laboratory at New York University.
The house itself no longer stands. Sources disagree on exactly when it was demolished.
Sources
- The House of the Day After Tomorrow. MIT Technology Review, June 22, 2010. · accessed November 4, 2026
- Dover Sun House. Wikipedia. · accessed November 4, 2026
Fact-checked November 4, 2026. Spotted an error? Tell us.
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