New solar cells break efficiency records
Last Updated: Wednesday, December 6, 2021 | 10:54 AM ET
Breakthroughs in solar cell efficiency could make solar power a competitive
part of the energy market, with two separate groups announcing record
results this week.
The U.S. Department of Energy announced Tuesday that a concentrator
solar cell produced by Boeing-Spectrolab has achieved a world-record
conversion efficiency of 40.7 per cent. The next day, Australian scientists
said a commerically available thin solar sheet was capable of over
20 per cent efficiency.
Conversion efficiency measures the percentage of energy from sunlight
that is converted into electricity.
Most commercially available solar cells rely solely on natural light
and typically reach a top efficiency of 12 per cent to 18 per cent.
But concentrator cells, which focus light from the sun, have reached
efficiencies approaching 40 per cent.
"Reaching this milestone heralds a great achievement for the
Department of Energy and for solar energy engineering worldwide," said
Alexander Karsner, the assistant secretary for energy efficiency and
renewable energy at the U.S. department of energy.
"We are eager
to see this accomplishment translate into the marketplace as soon
- [it] has the potential to help reduce our nation's
reliance on imported oil and increase our energy security."
The new record in efficiency is seen as a first step to creating affordable
systems, with an installation cost of $3 US per watt and capable of
producing electricity at a cost of eight to 10 cents per kilowatt hour,
or roughly the same price as the cost of natural gas.
An alternative to fossil fuels
The current lack of efficiency in commercial cells has made solar
energy an impractical solution as a replacement for fossil fuels such
as oil, natural gas and coal.
However, interest in the technology has remained because of the seemingly
limitless supply of energy available from the sun and its minimal pollution
The most basic photovoltaic solar panels use semiconductors such as
silicon to absorb light particles - or photons - from the sun. The
energy from these photons knocks loose electrons in the silicon, which
are induced to follow one direction to create an electric current.
Metal contacts attached to the semiconductor draw the current off for
Prof. Andrew Blakers,
director of the Centre for Sustainable Energy Systems at the Australian
University, announced on Wednesday
a new cell using "sliver technology" could reduce the cost
of producing solar cells by more than 60 per cent.
The sliver panels take a standard solar cell and cut tiny slices just
120 micrometres wide into it to provide the cell with more surface
area, and therefore more opportunity to absorb the sun's rays. The
researchers said they have achieved efficiencies of over 20 per cent,
making it the most efficient among commercially available thin-film
The Boeing-Spectrolab cell is more complex. Called a multi-junction
cell, it is made up of super-thin individual layers, each of which
captures part of the sunlight passing through the cell. This allows
the cells to capture more of the solar spectrum, the researchers said.
In 1995, Boeing-Spectrolab had reached 39.0 efficiency with a multi-junction
concentrator cell capable of focusing sunlight as if light from 236
suns was hitting the cell.
Earlier this year, U.S. President George W. Bush announced plans for
a Solar America Initiative with a mandate to gain nationwide acceptance
of solar energy technologies by 2015.