drbubb Posted June 2, 2007 Report Share Posted June 2, 2007 Freiburger Scientists break a Solar Cell World Record Multicrystalline Silicon Solar Cell with an Efficiency Value of 20.3 Percent Today, 55 % of all solar cells throughout the world are produced from multicrystalline silicon. In comparison to monocrystalline silicon, which commands a market share of 35 %, the multicrystalline material is less expensive but contains many more defects such as grain boundaries or dislocations. For this reason, the photovoltaic community has had to be content with efficiency values below 20 % for cells made of multicrystalline silicon, whereas this limit was already exceeded more than 20 years ago for monocrystalline material. Scientists at Fraunhofer ISE in Freiburg, Germany, are now the first to succeed in clearing this hurdle. After two years of work, a doctoral candidate in Stefan Glunz's group on high-efficiency silicon cells, Oliver Schultz, has successfully developed a process which allows the problematic defects to be partially "deactivated". "The trick is to choose temperatures during the solar cell production process such that the electrical properties of the multicrystalline silicon are improved and a high-efficiency solar cell structure is built up at the same time", explained Oliver Schultz. In this way, he has harmonised the high temperatures needed for a highly efficient solar cell with the temperatures that are "acceptable" to the material and are feasible in an industrial production process. Another important role in reaching the goal was played by a process for producing the back-surface contacts of the solar cell, which was also developed and patented by Fraunhofer ISE. So-called LFC technology, where LFC stands for Laser-Fired Contacts, is a industrial feasible process offering the ideal combination of potential for high efficiency values and low production costs. The expensive and slow photolithographic steps, that have been used up to now to produce the back-surface contacts of high-efficiency cells, are no longer needed. The LFC process can already be transferred to industrial production today. Further development steps are still needed to achieve this for the highly efficient front structure. "This barrier was not only physical but also psychological, so we are particularly proud to be the first to have broken through it", stated Gerhard Willeke, Head of the Solar Cell Department. @: http://72.14.235.104/search?q=cache:YTqY9g...t=clnk&cd=4 - - 20.1% efficiency achieved on large area thin silicon wafer PV cell The laser-grooved buried contact (LGBC) crystalline silicon solar cell has a selective emitter with excellent response to the solar spectrum in the wavelength range 300-900 nm. However, the cell efficiency is limited by a reduced response in the 900-1200 nm region of the spectrum due to the high recombination characteristics of the rear aluminium back surface contact and reduced internal reflection at this interface. The LGBC cell has now been fabricated with an aluminium laser-fired contact (LFC) through a passivating rear silicon oxide dielectric. By Nigel Mason, Oliver Schultz, Richard Russell, Stefan Glunz and Wilhelm Warta, BP Solar. @: http://www.insidegreentech.com/node/372 Technical paper : http://www.bp.com/liveassets/bp_internet/s.../2BP_1_1_2_.pdf Abstract : http://de.scientificcommons.org/2142957 Link to comment Share on other sites More sharing options...
drbubb Posted June 2, 2007 Author Report Share Posted June 2, 2007 The awards tour October, 2006: Just as at every international PV conference, many awards were bestowed upon deserving recipients in Dresden. A lifetime commitment: The SolarWorld Einstein Award went to Adolf Goetzberger (second from left), founder of the Fraunhofer Institute for Solar Energy Systems. »Next Generation« awards went to Oliver Schultz (also with ISE, far left) and Axel Herguth (University of Konstanz, third from right). For one, there was the Solar-World Einstein Award, which was brought to life one year ago by Germany‘s SolarWorld AG for the purpose of honoring persons who have put their heart and soul into the development of solar energy. This year, the award went to Adolf Goetzberger, 77, founder and long-time head of the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg, Germany, who was honored for his lifetime commitment. SolarWorld also bestowed two »junior awards,« aimed at supporting the next scientific generation, according to company head Frank Asbeck. These two awards went to physicist Axel Herguth (class of 1980) and Oliver Schultz (class of 1972). Both received the award for their research leading to higher efficiencies of crystalline solar cells. At ISE, Oliver Schultz designed silicon solar cells with a peak efficiency of 20.3 percent – from multicrystalline material, no less. Normally monocrystalline cells garner by far the highest efficiencies among silicon cells. The laboratory results are a world record, according to ISE. @: http://www.photon-magazine.com/news_archiv...&parent=538 CONTACT: Phone ++761-4588-5355; Fax ++761-4588-9250, email: Oliver.Schultz@ise.fraunhofer.de @: http://www.ise.fraunhofer.org/german/curre...ED_2CV.3.17.pdf Link to comment Share on other sites More sharing options...
HollandPark Posted June 4, 2007 Report Share Posted June 4, 2007 Great news. How long before they attack the 25% barrier- 10 years maybe? Link to comment Share on other sites More sharing options...
FunkyMucker Posted June 7, 2007 Report Share Posted June 7, 2007 Freiburger Scientists break a Solar Cell World RecordMulticrystalline Silicon Solar Cell with an Efficiency Value of 20.3 Percent Today, 55 % of all solar cells throughout the world are produced from multicrystalline silicon. In comparison to monocrystalline silicon, which commands a market share of 35 %, the multicrystalline material is less expensive but contains many more defects such as grain boundaries or dislocations. For this reason, the photovoltaic community has had to be content with efficiency values below 20 % for cells made of multicrystalline silicon, whereas this limit was already exceeded more than 20 years ago for monocrystalline material. Scientists at Fraunhofer ISE in Freiburg, Germany, are now the first to succeed in clearing this hurdle. After two years of work, a doctoral candidate in Stefan Glunz's group on high-efficiency silicon cells, Oliver Schultz, has successfully developed a process which allows the problematic defects to be partially "deactivated". "The trick is to choose temperatures during the solar cell production process such that the electrical properties of the multicrystalline silicon are improved and a high-efficiency solar cell structure is built up at the same time", explained Oliver Schultz. In this way, he has harmonised the high temperatures needed for a highly efficient solar cell with the temperatures that are "acceptable" to the material and are feasible in an industrial production process. Another important role in reaching the goal was played by a process for producing the back-surface contacts of the solar cell, which was also developed and patented by Fraunhofer ISE. So-called LFC technology, where LFC stands for Laser-Fired Contacts, is a industrial feasible process offering the ideal combination of potential for high efficiency values and low production costs. The expensive and slow photolithographic steps, that have been used up to now to produce the back-surface contacts of high-efficiency cells, are no longer needed. The LFC process can already be transferred to industrial production today. Further development steps are still needed to achieve this for the highly efficient front structure. "This barrier was not only physical but also psychological, so we are particularly proud to be the first to have broken through it", stated Gerhard Willeke, Head of the Solar Cell Department. @: http://72.14.235.104/search?q=cache:YTqY9g...t=clnk&cd=4 - - 20.1% efficiency achieved on large area thin silicon wafer PV cell The laser-grooved buried contact (LGBC) crystalline silicon solar cell has a selective emitter with excellent response to the solar spectrum in the wavelength range 300-900 nm. However, the cell efficiency is limited by a reduced response in the 900-1200 nm region of the spectrum due to the high recombination characteristics of the rear aluminium back surface contact and reduced internal reflection at this interface. The LGBC cell has now been fabricated with an aluminium laser-fired contact (LFC) through a passivating rear silicon oxide dielectric. By Nigel Mason, Oliver Schultz, Richard Russell, Stefan Glunz and Wilhelm Warta, BP Solar. @: http://www.insidegreentech.com/node/372 Technical paper : http://www.bp.com/liveassets/bp_internet/s.../2BP_1_1_2_.pdf Abstract : http://de.scientificcommons.org/2142957 Far superior? Link to comment Share on other sites More sharing options...
Billy Shears Posted June 8, 2007 Report Share Posted June 8, 2007 Far superior? Surely until such time as a large proportion of roofs and other likely surfaces are covered with solar cells, cost is going to be more important than efficiency. As large numbers of people are not going to add solar panels even if they double in efficiency. But if they halve in price at the current level of efficiency, many more people are likely to get one. And considering the price/output ratio, is this ratio going to be easier to improve with better efficiency, or cheaper price? Link to comment Share on other sites More sharing options...
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