By David L. Brown
Microscopic solar cells with the potential to bring solar power to places where no solar cell has gone before are being developed at the Sandia National Laboratories, Albuquerque, NM. The tiny cells are one-tenth the thickness of traditional solar cells and can potentially be attached to flexible backings that could be mounted onto any odd-shaped object such as buildings, clothing, or even camping tents, thus bringing solar power to anyplace where the Sun shines.
The tiny cells, described as “glitter-sized,” are made from crystalline silicon and are expected to eventually be cheaper to make and more efficient than present photovoltaic collectors, according to a news release. They can be made in present manufacturing facilities, using far less silicon than traditional solar cells and with less waste. The cells, pictured above, measure from 0.25 to 1 mm in size (1/100 to 1/25 inch).
According to Sandia field engineer Vipin Gupta larger installations on the roofs of houses and warehouses “could have intelligent controls, inverters and even storage built in at the chip level.”
Thinner than the thickness of a human hair, the chips perform as well as conventional cells that are ten times thicker. They use 100 times less silicon to generate the same amount of electricity, the researchers say. Because the cells are so small they are less sensitive to overhead obstructions that can cause conventional panels to turn off entirely when part of the surface is blocked from the Sun.
According to lead investigator Greg Nielson, the “glitter-sized” cells could allow campers, hunters and military personnel in the field to recharge cell phones, cameras and other electronic gear just by walking around in the Sun while wearing special clothing. Other potential uses are in satellites and remote sensing installations.
Solar concentrators, arrays of microscopic lenses to focus the sunlight, can be placed over the tiny cells to increase the efficiency by increasing the number of photons striking the cells. The concentrators should be cheaper to make and more efficient, again because of the small size of the cells.
Because of the large number of cells in an array, high-voltage output can be generated directly, reducing costs and taking advantage of lower losses due to electrical resistance in wiring at higher voltages.
Sandia Laboratories is operated by Lockheed-Martin Company for the Department of Energy’s National Nuclear Security Administration.
Below are pictured three of the Sandia research team members holding micro solar arrays; from left: Murat Okandan, Greg Nielson, Jose Luis Cruz-Campa.