Which is the most efficient solar cell

Solar cell with record efficiency

Solar cells © Michel Angelo, fotolia.com

Theoretically, the efficiency of silicon solar cells is 29 percent. On the other hand, only gallium arsenide cells that have already achieved an experimental efficiency of 41.1 percent achieve the highest commercially available efficiency of almost 30 percent. This is only made possible by the structure of the so-called multiple or tandem solar cell, in which two or more cells made of different materials are layered on top of one another. American researchers have succeeded in achieving an experimental efficiency of 44 percent, but now the 50 percent mark is to be cracked.

World record efficiency

At the latest after researchers at the Fraunhofer Institute for Solar Energy Systems (ISE) succeeded in setting a new world record for efficiency (41.1%) with the help of multiple solar cells, the ambition of the world of researchers to trump this world record has been fueled. Researchers at the U.S. Naval Research Laboratory (NRL) could now be on the verge of breaking the German world record. Your new multi-junction solar cell design should help and achieve an efficiency of around 50 percent. What currently sounds like a dream of the future could soon be achieved thanks to the special structure of the cells with three specially arranged photovoltaic layers.

The focus is on the arrangement

Multi-junction solar cells have the advantage that, due to their stacked arrangement, they can capture a very broad spectrum of light. The respective layers are optimized for very specific, different light wavelengths, so that the highest efficiency value achieved to date is 44 percent - a world record set by a triple solar cell from the National Renewable Energy Laboratory in collaboration with Solar Junction at the end of last year. Small downer: this level of efficiency could only be achieved under concentrated light.

Breakthrough seems within reach

A real technological breakthrough is needed to get even more efficiency out of the current solar modules. US Navy researchers are now hoping for this with the help of a completely new structure and using special structures and new semiconductor materials. All metal layers of the solar cell are adapted to the crystal structure of an indium phosphide substrate. With this design, direct band gaps of 1.8 electric volts are possible, which promises a particularly high yield, as it enables the cells to absorb a relatively large number of light particles.

Even higher degrees of efficiency are possible

Although this type of multi-solar cell is still in its infancy and its success has yet to be proven, the project, which will initially run for three years, is being financed by the US Department of Energy and sounds extremely promising. Should the 50 percent efficiency mark actually be broken, that would be a milestone in solar research. Theoretically, the maximum that can be achieved is almost 87 percent - but this would require an innumerable number of photovoltaic layers.

Category:Photovoltaics, top newsTags:Photovoltaics, efficiency