The Fraunhofer Institute for Solar
Energy Systems ISE, Soitec, CEA-Leti and the Helmholtz Center Berlin jointly
announced today having achieved a new world record for the conversion of
sunlight into electricity using a new solar cell structure with four solar
subcells. Surpassing competition after only over three years of research, and
entering the roadmap at world class level, a new record efficiency of 44.7% was
measured at a concentration of 297 suns. This indicates that 44.7% of the solar
spectrum's energy, from ultraviolet through to the infrared, is converted into
electrical energy. This is a major step towards reducing further the costs of
solar electricity and continues to pave the way to the 50% efficiency roadmap.
Back in May 2013, the German-French
team of Fraunhofer ISE, Soitec, CEA-Leti and the Helmholtz Center Berlin had
already announced a solar cell with 43.6% efficiency. Building on this result,
further intensive research work and optimization steps led to the present
efficiency of 44.7%.
These solar cells are used in
concentrator photovoltaics (CPV), a technology which achieves more than twice
the efficiency of conventional PV power plants in sun-rich locations. The
terrestrial use of so-called III-V multi-junction solar cells, which originally
came from space technology, has prevailed to realize highest efficiencies for
the conversion of sunlight to electricity. In this multi-junction solar cell,
several cells made out of different III-V semiconductor materials are stacked
on top of each other. The single subcells absorb different wavelength ranges of
the solar spectrum.
"We are incredibly proud of our
team which has been working now for three years on this four-junction solar
cell," says Frank Dimroth, Department Head and Project Leader in charge of
this development work at Fraunhofer ISE. "This four-junction solar cell
contains our collected expertise in this area over many years. Besides improved
materials and optimization of the structure, a new procedure called wafer
bonding plays a central role. With this technology, we are able to connect two
semiconductor crystals, which otherwise cannot be grown on top of each other
with high crystal quality. In this way we can produce the optimal semiconductor
combination to create the highest efficiency solar cells."
"This world record increasing
our efficiency level by more than 1 point in less than 4 months demonstrates
the extreme potential of our four-junction solar cell design which relies on
Soitec bonding techniques and expertise," says André-Jacques
Auberton-Hervé, Soitec's Chairman and CEO. "It confirms the acceleration
of the roadmap towards higher efficiencies which represents a key contributor
to competitiveness of our own CPV systems. We are very proud of this
achievement, a demonstration of a very successful collaboration."
"This new record value
reinforces the credibility of the direct semiconductor bonding approaches that
is developed in the frame of our collaboration with Soitec and Fraunhofer ISE.
We are very proud of this new result, confirming the broad path that exists in
solar technologies for advanced III-V semiconductor processing," said Leti
CEO Laurent Malier. Concentrator modules are produced by Soitec (started in
2005 under the name Concentrix Solar, a spin-off of Fraunhofer ISE). This
particularly efficient technology is employed in solar power plants located in
sun-rich regions with a high percentage of direct radiation. Presently Soitec
has CPV installations in 18 different countries including Italy, France, South
Africa and California.
Labels: New Research, Science