SolCold: chilling with the sun

Israeli start-up: the sun has never been cooler

The sun itself could soon become the source of an energy-saving air conditioner. A nano-filter paint layer developed by the Israeli start-up SolCold actually chill buildings when exposed to sunlight.

"With SolCold's innovative technology, the sun has never been cooler."

The technology is based on the principle of laser cooling, by which a laser can cool special materials by up to 150°C. Molecules in these materials absorb photons whose light is of one frequency, while re-emitting higher-frequency photons, which also carry more energy. Since there is a loss of energy, the temperature of the material is reduced in the process.

SolCold founder Yaron Shenhav wanted to see if he could adapt the process to make it work with sunlight instead.

“Heat from a building could be absorbed and re-emitted as light. As long as the sun is shining on it, it would be continuously cooled.”

The challenge is that the sun’s spectrum is much broader than that of laser light – a focused beam with a narrow range of frequencies. So the scientific team had to come up with a material adapted to using several frequencies of scattered light. They made a paint composed of two layers: an outer layer to filters out some of the sun’s rays and an inner one for the heat-to-light conversion.

SolCold - winner of Global Start-up Challenge Tel Aviv and runner-up in Shenzhen's Innovation & Entrepreneurship International competition - is currently nominated to the prestigious Hello Tomorrow summit 2020 to pitch alongside nearly 100 other start-ups.

Source: SolCold, New Scientist