Black silicon treatment achieves record PV energy performance
The technique treats the surface with a dry chemical that creates small conical tips at the nanometric scale.
Incorporating black silicon reduces the loss of energy caused by the reflectance of solar cells to almost zero thereby increasing the yield, by almost 4% compared with traditional solar cells.
The extra improvement in efficiency would allow a refrigerator to run for a day in a photovoltaic system composed of a 5 m2 panel.
To ensure that solar cells reflect as little light as possible and prevent energy loss, they are textured using an alkaline bath that forms a rough surface on which pyramids are randomly distributed. The technique makes the cells thicker because it consumes an amount of silicon in the process. Black silicon, however, allows thin silicon cells to be used, lowering production costs and saving silicon.
An added advantage achieved by researchers from the UPC and Aalto University in Finland is that, given the ability of black cells to capture solar radiation from lower angles, more electricity can be generated during a longer period throughout the day compared with traditional cells. In Finland the feature is important, because the sun shines from a low angle for most of the year and it has been demonstrated that cells made with black silicon generate more electricity than traditional cells that have the same degree of efficiency.
UPC researcher Pablo Ortega, claimed: "Within about three to four years it will be feasible to apply black silicon in the solar panel industry and the market in general."
