Finally, there’s a new type of solar concentrator being developed to generate solar energy without blocking the view. When it is placed over a window, it harvests solar energy while still allowing people to see through the window.
Researchers from Michigan State University call this new solar harvester a transparent Luminescent Solar Concentrator (LSC). The beauty of this new design is that it can be used on surfaces as large as buildings, as small as cell phones, and anything in between that has a flat, clear surface.
The Keyword is “Transparent”
According to Richard Lunt of MSU’s College of Engineering, the key word is “transparent.” Research to produce energy from solar cells placed around plastic-like luminescent materials is not new. However, the energy production was inefficient and the materials were brightly colored.
“No one wants to sit behind colored glass,” says Lunt, an assistant professor of chemical engineering and materials science. “It makes for a very colorful environment, like working in a disco. We take an approach where we actually make the luminescent active layer itself transparent.”
Harvesting the Solar Glow
This solar harvesting system uses small organic molecules developed by Lunt and his team to absorb specific nonvisible wavelengths of sunlight. “We can tune these materials to pick up just the ultraviolet and the near infrared wavelengths that then ‘glow’ at another wavelength in the infrared,” he says.
The “glowing” infrared light is guided to the edge of the plastic where it is converted to electricity by thin strips of photovoltaic solar cells. “Because the materials do not absorb or emit light in the visible spectrum,” Lunt says, “they look exceptionally transparent to the human eye.”
A Work in Progress
According to the MSU team, the technology is still at an early stage. More work is needed to improve its energy-producing efficiency. Currently the clear LSC is achieving a solar conversion efficiency close to 1 percent. The team aims to reach efficiencies beyond 5 percent when it is fully optimized. By comparison, the best colored LSC has an efficiency of around 7 percent.
Other members of the MSU research team include Yimu Zhao, an MSU doctoral student in chemical engineering and materials science; Benjamin Levine, assistant professor of chemistry; and Garrett Meek, doctoral student in chemistry. Their work with transparent solar was recently featured on the cover of the journal, Advanced Optical Materials.
Industrial Scale at Affordable Cost
One of the benefits of this new transparent solar energy harvesting is its flexibility. It has the potential to be scaled to commercial or industrial applications at an affordable cost, a tantalizing factor in climate change mitigation strategies.
“It opens a lot of area to deploy solar energy in a non-intrusive way,” Lunt says. “It can be used on tall buildings with lots of windows or any kind of mobile device that demands high aesthetic quality like a phone or e-reader. Ultimately we want to make solar harvesting surfaces that you do not even know are there.”
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(Top Image Source and Note: MSU doctoral student Yimu Zhao holds up a transparent luminescent solar concentrator module. Credit: Yimu Zhao)