The photovoltaic cells that are currently being developed for harnessing the sun’s power only absorb a small portion of light, wasting a lot of solar energy in the process and could be collecting solar energy more efficiently. Thanks to the advancements of technology, a new material is now being developed in order to harness all the wasted energy arriving on the photovoltaic cells.
Traditional solar panels are made up with silicon. When the sunlight touches the silicon atoms on a solar panel, the atoms’ outermost electrons absorb the wavelengths of sunlight, causing the electrons to get charged. Once the electrons have enough charge, they move independently throughout the panels in order to produce electricity.
The problem is, despite being able to absorb some wavelengths, today’s solar panels cannot absorb longer wavelengths that just pass through the silicon. The longer wavelengths are never converted into electricity and a better panel that absorbed more wavelengths would end up collecting solar energy efficiently.
“The silicon absorbs only a certain fraction of the spectrum, and it’s transparent to the rest,”
said Harry Atwater, the new material’s head researcher. And, also:
“If I put a photovoltaic module on my roof, the silicon absorbs that portion of the spectrum, and some of that light gets converted into power. But the rest of it ends up just heating up my roof.”
Atwater’s team of researchers has found a way to absorb the wasted energy by using a new material that is not composed of silicon but of pure metal.
“Normally in a metal like silver or copper or gold, the density of electrons in that metal is fixed; it’s just a property of the material,” said Atwater. “But in the lab, I can add electrons to the atoms of metal nanostructures and charge them up. And when I do that, the resonance frequency will change.”
Caltech’s new material, if successful, would be a breakthrough in the world of concentrated photovoltaics (CPV). CPV is a cousin of Concentrated Solar Power (CSP), which also uses the sun’s power in generating electricity but with different methods.
Today, one of the ways to increase the efficiency of power generation is by combining a CSP plant with a fossil-fired power plant. Sulzer, a Swiss-based engineering and manufacturing firm that is in a joint venture with Unaoil in providing rotating equipment maintenance, is a pioneer in making this technology possible. A Hybrid Integrated Solar Combined Cycle (ISCC) boosts electrical output by using steam and thermal energy.
While ISCC already increases electrical output at a low cost, Caltech’s new technology will enable a new generation of solar panels collecting solar energy efficiently. which will hopefully generate more power at a lower cost.