Despite how far solar cells have come in recent years, issues like production and installation costs have remained an ongoing obstacle to their full scale adoption. But as they say, obstacles are meant to be overcome, and can often produce very interesting solutions. For example, peel and stick solar panels that can be manufactured by a 3D printer are one option. Another is the recent creation of a solar cell as thin as a strand of hair. And as it happens, a third has just been unveiled.
This latest one comes to us from the University of Oslo, where researchers have come up with a way to produce silicon solar cells that are twenty times thinner than commercial solar cells. Typically, solar cells are fashioned out of 200-micrometer-thick (0.2mm) wafers of silicon, which given their average rate of power generation works out to about five grams of silicon per watt of solar power. Combined with all the silicon wasted in the production process, this makes for a very inefficient process.
One way around this is to reduce the thickness of solar wafers, but this presents its own problems. As the wafer gets thinner, more light passes straight through the silicon, dramatically reducing the amount of electricity produced by the photovoltaic effect. Blue light, which has a short wavelength, can be absorbed by a very thin solar cell; but red light, which has longer wavelengths, can only be captured by thicker wafers.
Enter into this the breakthrough created by the Oslo researchers. Using a revolutionary technique involving microbeads – tiny plastic spheres that create an almost perfect periodic pattern on the silicon. Apparently, these beads force the sunlight to “move sideways,” ensuring a more uniform and powerful rate of absorption. Another trick is to dot the backs of each cell with asymmetric microindentations,which can trap even more solar energy.
Using these techniques, silicon wafers can be created that measure a mere 10 micrometers in thickness but can do the job of a 200 micrometer cell. By using 95% less silicon, the cost of production drops considerably, which will reduce the cost of solar power installations and – more importantly – increase profits. With current production methods and costs, the profit margin associated with solar power is pretty negligible.
This latter aspect is especially important as far as commercial production comes into play. If we are to expect industries to adopt solar power for their energy needs, it has to be worth their while. At the moment, the Oslo researchers are in talks with industrial partners to investigate whether these methods can be scaled up to industrial production. But given the nature of their work, they seem quite confident that their technology could come to the market within five to seven years.
Stay tuned for more installments in the PBTS series!