Solar panels efficiency has always been a great problem. The low results obtained in many cases make compulsory to search for new solutions. Researchers from Stanford University have developed some kind of ‘invisible wires’ to increase the efficiency. Although other factors such as the integration of solar panels in buildings is even more crucial than these developments, it is a great step forward. Let’s see how they have achieved it.
Invisible wires to increase efficiency
Solar panels have commonly a grid division. That grid is made of a metal material. Although it is necessary to have that metal connection, at the same time, it reduces the efficiency of the panel. The metal reflects part of the light that would reach the panel, therefore, less energy can be produced.
Researchers from the University of Stanford have found a solution to this slight problem. The solution can be summarized as following: create nanosized pillars of silicon that “tower” above the gold film and redirect the sunlight before it hits the metallic surface. One of the authors explains the chemical process:
“We immersed the silicon and the perforated gold film together in a solution of hydrofluoric acid and hydrogen peroxide,” said graduate student and study co-author Thomas Hymel. “The gold film immediately began sinking into the silicon substrate, and silicon nanopillars began popping up through the holes in the film.” “As soon as the silicon nanopillars began to emerge, they started funneling light around the metal grid and into the silicon substrate underneath,” Narasimhan explained.
The best way to explain the process, as the authors say, is a sink. If you open the tap, not all the water go through the holes of the colander. However, if we put a funnel, the water will go faster. If we take into account that 5 to 10 percent of the surface of solar cells is made of those metal grids, the solution is really interesting. According to the tests and simullations carried out, the efficiency of the panel is increased about 2% in a common solar panel. It isn’t an outstanding result, but research in photovoltaics is difficult.