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Clean Power
Solar Panels From CPT Break Efficiency Barrier
By
Steve Hanley
In 1961, William
Shockley and Hans-Joachim Queisser calculated that the
maximum theoretical efficiency of a silicon-based solar panel is 30%.
In other words, less than a third of the sunlight that strikes a solar
panel can be turned into electricity.
Today, only high end solar panels intended for use in spacecraft get
near that maximum efficiency limit. Those panels are far too
expensive for normal commercial use. The average panels
used on rooftops and in solar farms are much less expensive, but have
an efficiency of around 22%.
The problem is that silicon only responds to certain wavelengths,
particularly those in the red and yellow portion of the
electromagnetic spectrum. Longer light waves in the infrared part of
the spectrum are too weak to create an electrical current. Shorter
light waves in the blue and green part of the spectrum don’t create
any electrical current when they strike the silicon in a solar cell —
at most, they bounce off. At worst, they generate heat, which degrades
the efficiency of panels.
A Bright Idea Becomes A New Business
In 2014, Akshay Rao and a team of researchers at the University of
Cambridge had a bright idea. What if there was a way to convert those
blue and green light waves into red light waves? That would boost the
efficiency of a solar panel to around 35% — roughly 50% more than the
conventional solar panels in use today. Can you image what that would
mean to the world of renewable energy?
The University of Cambridge took that idea and used it as the basis of
a new technology company known as Cambridge
Photon Technology. Here’s how it works, according to a
study published in the journal Nature.
“Rao developed a photon multiplier film made up of a layer of an
organic polymer called pentacene studded with lead selenide quantum
dots — small, light emitting clumps of inorganic material. The polymer
absorbs blue and green photons and converts them into pairs of
excitons. These excitons flow to the quantum dots, which absorb them
and emit lower energy red or infrared photons.
“When the film is placed on top of a silicon solar cell, the light
from the quantum dots shines onto the silicon. Meanwhile, the red and
infrared wavelengths directly from the sun pass through the polymer
film and hit the silicon as they normally would. The result is that
more usable photons strike the silicon, increasing production of
electrical current.”
“You’re preserving the total energy that comes in and out, but you’re
making the silicon receive a higher photon flux in the portion of the
spectrum that it’s good at converting into electricity,” Wilson says.
For more on how this works, see the video below.
Progress Takes Time
Did you notice that the research that started this all began in 2014?
Here we are 8 years later, and Rao says he hopes to have a working
prototype that is 31% efficient by the end of 2022. The target for the
panel that is 35% efficient is 2025 at the earliest. Notice how this
news is similar to the stories we report on all the time about
breakthroughs in battery technology. Coming up with new ideas is easy.
Turning them into commercially viable products is hard.
The key to the CPT approach is that its photon splitting layer can be
applied to any solar panel during the manufacturing process without
any significant changes in the production phase. That’s a critical
consideration if the new technology is to have any hope of being
commercially successful. “Our whole approach has been…to make a
simple, non-toxic material with no electrical connections that add
very little complication to existing design,” Wilson says.
Once CPT proves its technology is viable, the potential pay-off could
be great, Wilson says. “It’s really clear that there’s a fairly urgent
need and this technology, if it works as promised, will go a long way
to meeting that need.” We — and
the world — can hardly wait.
Green Play Ammonia™, Yielder® NFuel Energy.
Spokane, Washington. 99212
www.exactrix.com
509 995 1879 cell, Pacific.
Nathan1@greenplayammonia.com
exactrix@exactrix.com
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