Solar companies not yet beaming about new nanotube black

The new black is, well, blacker, and that could be good news for the solar industry.

A thin material composed of low-density arrays of loosely vertically aligned carbon nanotubes developed by researchers from Rensselaer Polytechnic Institute and Rice University could increase solar conversion efficiencies.

Black paint reflects 5 to 10 percent of light. Until the Rensselaer team released its study in the journal Nano Letters, the darkest man-made material reflected just 0.16 percent to 0.18 percent of light.

But the new nanotube material trumps that, with a total reflective index of 0.045 percent. The researchers have applied for a Guinness World Record.

"The loosely packed forest of carbon nanotubes, which is full of nanoscale gaps and holes to collect and trap light, is what gives this material its unique properties," project leader and Rensselaer physics professor Shawn-Yu Lin.

"Such a nanotube array not only reflects light weakly, but also absorbs light strongly. These combined features make it an ideal candidate for one day realizing a super black object."

Several solar energy companies, including Mountain View, California-based company SolFocus, are said to have already contacted Lin to ask about the new material.

"Unfortunately I cannot confirm or discuss any activities we have going on in the R&D area. Sorry not to be able to be more helpful but I’m sure you understand our position of not discussing any investigations, future products, etc.," said Nancy Hartsoch, SolFocus’ vice president of marketing, to the Cleantech Group.

Other solar companies are also cautious about the new material’s potential applications.

In an email to the Cleantech Group, Marc Cortez, executive vice president of sales and marketing at the Pasadena, California-based Soliant Energy said it’s too early to predict how the new darkest material will affect the solar energy industry.

"The ultimate challenge will be to take it from the lab into a high-volume manufacturing environment," he said. "It’s only then you’ll know whether or not it will be a 'game-changing' technology."

Rick Lewandowski, CEO of Stone Ridge, New York's Prism Solar Technologies, called the Rensselaer work "very interesting," especially since the PV industry is working on increasing the benefits of anti-reflective coating.

"But I would also think this is an interesting product for solar thermal applications since they use anti-reflecting black surfaces," he added. "This may play a part in that. It may increase efficiency but it does look interesting from our perspective."