ENERGIES RENOUVELABLES sol(ID)aires
LE FUTUR DU SOLAIRE PV
Nouveautés internationales
2003
ENERGIES RENOUVELABLES sol(ID)aires
| Allemagne,
une pile solaire ultra-fine qui produit
plus de courant
Des chercheurs de l'Institut Fraunhofer pour les systèmes à energie solaire (ISE - Fraunhofer Institut fur Solare Energiesysteme) de Fribourg-en-Brisgau (Bade-Wurtenberg) ont mis au point une nouvelle technique très économique, permettant de fabriquer des piles solaires cristallines au silicium de 37 micrometres (microm) d'épaisseur. Ces piles solaires ultra-fines ont un rendement de 20,2%, une nette amélioration par rapport aux piles solaires actuelles qui font 300microm d'epaisseur, et dont le rendement est de 16% environ. La technique dite "Technique LFC" (Laser Fired Contacts) offre la possibilite d'obtenir des rendements très élevés avec des coûts de production bas: avec ce processus, la couche d'aluminium est vaporisée directement sur la couche de passivation. Un laser chauffe ensuite le métal afin de fabriquer les contacts. Ce processus est économique, rapide (une seconde par pile solaire), son résultat plus esthétique. Le système fonctionne indépendamment de l'épaisseur du wafer ou du niveau de dopage, ce qui correspond aux critères nécessaires pour une production industrielle massive. Contacts : - Fraunhofer Institut fur Solare Energie Systeme ISE, Heidendorfstr. 2, D-79110 Freiburg Presse et relations publiques: Karin Schneider, e-mail : info@ise.fhg.de - Dr Stefan Gunz, e-Mail: stefan.glunz@ise.fhg.de Novel Semiconductor Could Soup Up Solar Cells, (Scientific American - 10 nov 2003) Sources : Handelsblatt, 04/12/2003 In recent weeks, some of the most powerful solar flares ever witnessed have sent electrically charged gas shooting toward the earth in so-called coronal mass ejections. But even without such impressive displays, the sun provides a wealth of energy to our planet. Unfortunately, efforts to mass produce solar cells to harness energy from Sol have stalled at efficiencies of around 30 percent in the laboratory and less than 20 percent in commercial cells. A novel crystal described in a paper set to be published in the journal Physical Review Letters may change that, however. Scientists report that the semiconductor material could form the basis of solar cells with nearly 50 percent efficiency. In a standard photovoltaic cell, the sun's rays are converted into electricity when electrons within the material are knocked loose. To accomplish this the incoming light must have a specific energy, known as the band gap. Incident light with less energy will not be absorbed, while the portion of more energetic radiation above the band gap will be lost. In an attempt to alleviate this problem, Kin Yu of Lawrence Berkeley National Laboratory and colleagues investigated the properties of a new semiconductor material comprising an alloy of zinc, manganese and tellurium. |
The researchers added oxygen impurities to the crystal,
which resulted in a crystal having three band gaps instead of the customary
one. "These three absorption edges span much of the solar spectrum," they
write, "thus these alloys are good candidates for the multi-band semiconductors
envisioned for high efficiency photovoltaic devices." The
scientists further theorize that the efficiency could be increased to as
much as 56 percent by changing the ratio of the atoms or replacing
manganese with magnesium.
Sarah Graham
Nouvelles perspectives pour líénergie solaire Un nouveau procédé vient díêtre
mis au point par les chercheurs díEDF et du CNRS/ENSCP*, qui offre
des perspectives réelles pour un déploiement important du
photovoltaïque.
|
