Infrared Photovoltaic Panels? Exciting Technology on the Horizon - GD 2.01

Solar energy has made considerable gains in efficiency in the last decade and better yet, the price of photovoltaic (PV) panels has dropped significantly.

However, one feature of PV panels is that they are virtually unresponsive to the infrared part of the light spectrum. About 40% of the sun's energy reaching Earth is in the infrared range. By developing PV panels that can transform even a fraction of infrared light into electrical current, we could create a vast increase in PV efficiency and power output.

How about night-time? Everyone knows that PV cells don't produce electrical current in the dark. So right off the bat, we're losing at least 50% efficiency on every PV panel no matter how good it is, because more than half the time it doesn't work.

Here are two interesting pieces of research that together could forever alter the utility of solar PV panels.

First -

http://www.popsci.com/science/article/2011-11/new-glow-dark-material-only-glows-infrared-light

Second - 

http://web.mit.edu/newsoffice/2012/infrared-photovoltaic-0621.html

The first link - an article in Popular Science online magazine - is about a new phosphorescent liquid developed by researchers at the University of Georgia that charges up in about one minute and emits light in the infrared range for up to two weeks.

To quote popsci.com:

"They tested it in natural sunlight, color-filtered sunlight and fluorescent light, and found it works with just a few seconds of light exposure, even on a cloudy day. It works in liquid, too, including tap water, saltwater and bleach, which could make it very useful for deep-sea applications or even in living organisms. The material could also be useful in developing more efficient solar cells, nanoparticles that bind to cancer cells, or in infrared paint only viewable by people with IR goggles, the researchers say."

This is great because you could actually put this liquid within a plastic film that could be rolled out automatically over PV arrays to charge for just a few minutes a day, roll back up, and then roll out over the PV panels overnight.

"But I thought you said that PV panels ignore infrared?"
--Yes. However, a new material composed of a specific type of carbon nanotubes and C60 (AKA Buckyballs) actually does the job. According to the article on MIT's website:

"The carbon-based cell is most effective at capturing sunlight in the near-infrared region. Because the material is transparent to visible light, such cells could be overlaid on conventional solar cells, creating a tandem device that could harness most of the energy of sunlight."

However, it's still in the research and development phase.

"The carbon cells will need refining, Strano and his colleagues say: So far, the early proof-of-concept devices have an energy-conversion efficiency of only about 0.1 percent."

While 0.1% sounds rather minuscule, it's important to point out that new solar technology generally begins at low efficiencies and gradually get better through the development process. And also, 0.1% efficiency is actually a lot better than what photovoltaics are currently getting out of infrared light, which is nothing.

Once the kinks are worked out, PV panels could be constructed with an infrared-gathering carbon nanotube layer working all day, and working all night because you unrolled your infrared-glowing phosphorescent sheet on top of it.

Keep an eye out for innovations like these!