Michigan Tech scientists have proposed a new technique that could reduce solar cell production costs by more than 10 percent.
“Improving cost per unit power at the cell level can have massive effects downstream,” says Joshua Pearce, professor of material sciences and electrical engineering at Michigan Tech.
Costs of solar energy is now comparable to other forms of electricity and is the fastest growing energy source, intones Pearce. This 10 percent drop should push solar to the forefront even faster.
Silicon consist of two main forms: perfect crystals that cost more and produce higher efficiencies and multicrystalline silicon that cost less, but offers lower efficiencies.
Common etchings to reduce reflected light is what gives most solar panels their blue color. It doesn’t however prevent them from losing some light.
Researchers already know that nano-texturing silicon with dry etching makes black silicon (black-Si) more efficient at capturing light than standard etching treatments.
It has no color because the dry etching process takes a normally flat silicon surface and etches it into a forest of nanoscale needles, says Pearce: “Those needles grab the light and don’t let it get away. It’s like looking into the eyes of Darth Vader.”
Normally such a high surface area with many surface defects would hurt electrical performance, but researchers at Aalto University found that when the silicon is also treated with an appropriate atomic layer deposition (ALD) coating, the effects of surface defects are mitigated.
While researchers did find that production of individual black-Si passive emitter rear cells (PERC) were between 15.8 and 25.1 percent more expensive than making conventional cells, they also found that the efficiency gains and the ability to go to the less-expensive multicrystalline silicon starting material far outweighed those extra costs.
Overall the cost per unit power dropped by 10.8 percent, reports the researchers.
This study was conducted with Chiara Modanese, Hannu Laine, Toni Pasanen and Hele Savin from Aalto University.
Image credit and content: Pexels-Carl Attard/Michigan Tech
