A Silver Tree For Solar PV Photosynthesis

For years the energy industry was all about overpowering nature, outsmarting nature, beating nature. But the last decade or so of realizations about climate change and greenhouse gas emissions has led the energy industry right back to the laws and wisdom of nature. Now some engineers are looking at trees–which naturally absorb sunlight to create energy–for wisdom on how to build the most efficient solar panel. They are most interested in how to reduce the amount of silver in solar cells, a commodity whose price is increasingly volatile and expensive.

All silicon-based solar photovolatic (PV) panels use a silver-based paste for the panel’s contact grid, using around 0.10 grams of silver for each watt of generating capacity, or about 20 grams of silver in a 200-watt panel, according to New Energy Finance. According to Bloomberg online, the solar PV industry consumes around 11 percent of the world’s silver supply, with the cost of silver quickly rising from $20.24/ounce in 2010 to $35.30 in mid-2011.

image via UC Davis

Now a group of chemists at the University of California at Davis, led by Professor Frank Osterloh, may have found a way to use silver to mimic nature and achieve nearly the same efficiency as plant photosynthesis. The researchers found that microscopic “fractal trees” of silver, about one-fiftieth the width of a human hair, could be the basis of a new solar cell. Fractals are repeating patterns that branch out in a self-similar pattern so that they look nearly the same from close up and far away. They have a wide surface area like a real tree, and when coated with light-absorbing polymers, can very efficiently catch sunlight and turn it into electricity. Most importantly they use less silver to produce better results.

As solar power becomes increasingly popular in the United States and around the globe, and developers increasingly install large commercial-scale solar plants, scientists have been working to perfect PV panels and make them as cheap and efficient as possible. In fact, the popularity of solar has been a bit of a mixed blessings for the industry. Production capacity skyrocketed, helping to drive down prices, but manufacturing costs remain relatively high as commodity prices spike with the increased demand.

Even if the silver fractal tree works to lower the price of silver, solar manufacturers still have to struggle with the commodity prices of silicon and the other components used in solar panels. Engineers are trying to use nanotechnology to reduce the prices of other solar components as well. (Read more here.) Some of those commodities are cheaper than they ever were, but the global markets will definitely be keeping manufacturers and engineers on their toes as they try to keep technology and prices sustainable. This is particularly true as governments around the world race towards various 2020 renewable energy goals, that will put added pressure on renewable energy manufacturers.

Also a challenge will be continued funding of renewable energy research, as engineers continue to churn out new ideas and cheaper solutions. The silver fractal research was funded with a $100,000 grant from the Research Corporation for Scientific Advancement, which has been funding Osterloh’s research lab on solar power since 2010.

Shifra Mincer is a freelance journalist and passionate tweeter (@Shiframincer) currently living in Israel. Before moving to Israel to apprentice with a homebirth midwife, Shifra worked as Associate Editor of AOL Energy, and was a member of the launch team that got the site up and running. Shifra has over a half a decade of experience in journalism and has written on women's health, green technology, politics and regulation of the energy industry, energy financial news, and local news. While studying for her B.A. at Harvard College, Shifra worked as a news editor for the Harvard Crimson. Shifra is also a yoga teacher and a birth doula and is hoping to create an active Jewish birth community through her web venture www.layda.org.

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