This robust, low-cost solution allows for homes to be heated reliably and cheaply in challenging high-mountain regions like the Argentinian and Bolivian Altiplano, Ladakh and Kargil in the Himalayas.

Based on proven technology, a simple solar air heater circulates air through a rock bed below the floor in a closed loop. The floor provides under-floor heating, creating an ideal temperature distribution in the room. Due to the big thermal capacity of the rock bed, rooms are heated 24h per day, even during 1-2 days without sun. No more searching for fire wood, or buying gas, no more smoke in the rooms which contributes to respiratory diseases or carbon monoxide incidents.


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Key features for a positive impact on quality of life

  • Air is used as heat transfer medium - no anti-freezing agent, no pressure at stagnation temperature in summer, no corrosion. Small leakages do not affect performance. No electronics used.
  • Modularity allows adaptation to many consumer needs from collector sizes of 2 m² to 120 m²
  • Easy to transport and assemble, due to sturdy modular design at low weight. Glass is placed during installation.
  • Rocks are available in many regions at low cost which is permitting big storage heat capacity, so the heat demand can even be covered for 1-2 days without sun
  • Minimal user operation required. Just a on/off switch for the automatic fan operation in heating season.

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  • Depending on the region, the system saves up to 90% of the conventional fuel used for space heating, translating to 370 USD/year per home in Ladakh and Kargil.
  • Initial investment is paid off within 4-5 years.
  • Locally sourced and produced materials allow for easy maintenance and job creation in the region

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solar space heating for a school in the Argentinean Altiplano

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transport of locally fabricated collector segments for solar space heating in Argentina


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roof integrated installation



functional diagram:

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video about the project in Ladakh

video about the proejct in Argentina