Most of the light from our Sun comes as part of the light spectrum we cannot see. Now infrared radiation promises to change the way solar technology is being developed and deployed.
Drawing free solar power from the sun has always been an attractive idea.
Augustin Mouchot reported in 1869 that 15th Century Arab alchemist were using polished Damascus mirrors to distill water.
Since the last century, the promise of solar power has been improving steadily, and solar tech is becoming more efficient and more powerful, and regardless of the fact that Americans are still paying more than most, solar is cheaper than ever before.
What else would you expect from a technology that produces its own energy?
Well, the University of California (UCR), who last year opened a brand new solar farm that will produce up to 6.6 million kilowatt hours of electricity each year, has just found a new way to make photovoltaic power even better.
The researchers at UCR have discovered that, by converting infrared light into a form that solar panels can use, they can improve the output of existing solar technology by as much as 30%!
Currently, solar cells absorb only visible light.
Visible light is the easiest to study because, well, it’s visible.
So it’s easy to understand why technologies that use light to generate power would tend to depend mostly on the type of light that is most familiar to our senses.
But, what is important to remember, however, is that visible light accounts for less than half of the solar power that is constantly pouring over the Earth’s surface.
The majority of the solar radiation we receive from the Sun comes in the form of infrared light. But, if you understand how solar cells work, you would know that infrared light is normally useless as an energy source because it passes right through traditional photovoltaic cells without producing a single usable electron.
By creating hybrid materials that enable solar panels to absorb infrared radiation, researchers at UCR have nearly doubled the power output of existing solar collectors. They do this by “upconverting” infrared rays into a more energetic type of photon that is readily accepted by conventional solar cells.
The process involves inorganic semiconductor nanocrystals which catch infrared photons, along with certain inorganic molecules. The inorganic molecules combine two or more infrared photons, making them unable to pass through the cell without striking the solar collector and generating free electrons.
It’s an approach that sidesteps the usual thinking about broadening the available spectrum of light to solar panels.
In essence, most teams working on the same problem have been focused on trying to get solar panels to accept different kinds of light. The team in UCR has, instead, opted to adapt the light to the cell. It’s a small technical distinction, but one that has held researchers back from the goal of utilizing infrared light until now.
The cost of the upgrade that existing solar panels will need to use this new technology are not yet known.
But one thing is clear, however. Rather than just adapting existing solar panels, implementing this new innovation would be less expensive than manufacturing an entirely new kind of solar cell.
This research also breaks new ground into alternate light which could allow a wider deployment of solar power worldwide. Plenty of usable raw energy is available, even on overcast days, but the distribution of it through the spectrum is different, and extremely hard for existing panels to convert into usable power.
Infrared radiation moves through a cloudy sky quite easily. If infrared energy could be added to that of visible light, solar power systems are likely to begin making good financial sense in parts of the world that aren’t quite as sun-drenched as Texas and California.
Tom Miller
