Transparent Solar Cells: The Future of Energy Production

This is a solar energy cell (source)

by Gaius Publius

The news about solar energy has been getting better and better for a decade or more. As storage schemes improve, so does the potential for completely replacing fossil fuels with renewable energy sources.

The latest information about solar energy cells, however, seems like a game-changer. In a nutshell, it's now possible to harvest and use the energy of the sun, not just as it strikes opaque surfaces, but also as it passes through transparent ones. Considering the number of transparent surfaces in the country — and in fact in the world — the potential for integrating light-harnessing energy cells into our lives and infrastructure, all of it invisibly, has increased by many orders of magnitude.

Consider that every pane of glass in every office building, house and apartment, every "gorilla glass" screen on every smart phone, every windshield of every car. and every other glass surface you can imagine — windows inside office buildings? mirrors? — can now be used to harvest energy from light and send it to be used or stored.

Then consider how much fossil fuel use that can replace. The developers of this technology say, eventually all of it. The story via Newsweek:

A new generation of see-through solar cell technology could soon be used to harvest the massive energy potential of building and car windows, cell phones as well as other objects with a transparent surface.

Scientists at Michigan State University detailed in a paper in the journal Nature Energy how highly transparent solar applications could “nearly meet U.S. electricity demand” and drastically reduce reliance upon fossil fuels.

“We will see commercial products become available over the next few years,” Richard Lunt, an associate professor of Chemical Engineering and Materials Science at MSU, tells Newsweek. “We are just beginning to hit performance metrics that make sense to scale up.” ...

The untapped electricity potential of this energy source, the researchers note, is vast. An estimated 5 billion to 7 billion square meters of glass surface in the United States could be used to meet 40 percent of the country’s energy demand, or “close to 100 percent” if energy storage is improved.

That journal article is here (subscription required).

The trick involves collecting the energy from non-visible wavelengths of the electromagnetic spectrum, of which visible light is just a part. In this case, the energy is collected from ultraviolet and "near infrared" wavelengths. Light from these wavelengths is then "guided to the edge of the surface they are on [and] converted into electricity by thin strips of photovoltaic solar cells."

The work is being done by a team at Michigan State University, which has previously published on this technology.

A few things to keep in mind. First, these cells don't replace glass, but fit over glass surfaces without reducing their transparency. In the announcement published by MSU, these cells are described as see-through "solar materials that can be applied to windows." This means already-installed windows won't have to be replaced in order to benefit from this technology.

Second, efficiency is obviously a factor in the amount of energy the technology provides: 

Compared to traditional solar cells, the transparent technology still has some catching up to do. Rooftop solar panels typically have an efficiency of between 15 and 18 percent, whereas the see-through solar cells record efficiencies of around 5 percent. However, Lunt says he expects to see a three-fold improvement in efficiency of the transparent solar cells.

Finally, the project is financed by the National Science Foundation and the U.S. Department of Education (interestingly, not the Department of Energy). If this story gets wider attention and the potential of this technology becomes more publicly appreciated, will Betsy Devos' DoE pull funding for the project? That aspect is worth paying attention to as this exciting research starts making even more news.

GP