Basking in the sun: The prototype of IBM’s liquid metal cooling system for concentrated photovoltaic cells can endure highly focused solar energy without overheating.
IBM’s solution is to place an ultrathin layer of liquid metal, a compound of gallium and indium, between the two surfaces. “The main benefit here is that it’s a metal, so it has a very high thermal conductivity,” says Guha. And because it’s a liquid, it is possible to make this layer extremely thin, typically around 10 micrometers.
Using this simple solution, Guha and his colleagues have demonstrated that they can focus the equivalent of 2,300 times the sun’s natural energy on a one-centimeter-square photovoltaic chip. Without cooling, this would melt steel, he says. The photovoltaic cell temperature would be in excess of 1,500 °C, and therefore would simply vaporize. With the liquid metal and water-cooling system, the IBM photovoltaic material remains at 85 °C.
“I’m sure there will be interest from [concentrated photovoltaic] companies, and it’s definitely something we would want to investigate,” says Stephen Bates, CEO of Whitfield Solar, in Reading, U.K. “But it would have to be exceptionally low cost because the industry is so incredibly price sensitive,” he says.
However, despite the promise of this approach, IBM is not planning on branching out into the solar-energy market. “We don’t plan to make [concentrated photovoltaic] systems,” says Guha. Instead, IBM is in talks with solar-cell companies about licensing the technology, he says.