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A low-cost, plastic solar lamp could provide affordable lighting for millions living in rural off-grid areas across Africa.

The lamp is made from polymer solar cells and although it is not as efficient as similar technologies, it could prove more affordable, according to its developers.

"There are many technologies out there already that are established and better performing … but perhaps these do not have the potential to go much lower in cost," said lead researcher Frederik Krebs, from the Risø National Laboratory for Sustainable Energy, in Denmark.

Several versions of the lamp are under development, following trials on a prototype in Zambia in 2009. One, a pocket-sized torch that could be used for night-time navigation, is ready to be rolled out commercially and Krebs is confident that it could be produced for as little as €3 (around US$4).

He suggested that 'microfinance' schemes, where people collaborate to buy a lamp which they can share, would be useful for people who cannot afford this initial outlay.

David Grimshaw, head of the international programme on new technologies at Practical Action — a UK-based charity that uses technology to challenge poverty — welcomed this research.

"It demonstrates that polymer solar cells can now approach a cost level … where they could be adopted by the poor."

Solar lighting is an important alternative to the kerosene lamps currently used in off-grid developing areas, said David Battley from charity SolarAid, based in the United Kingdom, which promotes the use of solar energy to help reduce global poverty and climate change. Kerosene lamps are a fire hazard, release damaging fumes, and place a financial burden on the user who constantly has to buy fuel.

"The availability of essentially free lighting — after the point of initial purchase — has massive benefits to both health and education," said Battley.

"It should be absolutely sustainable, so it's not dependent on Western funding."

The field trials allowed researchers to improve subsequent versions of the lamp by identifying the problems users encountered. For example, some people mistakenly charged the lamp upside down, reducing efficiency. Others charged it in front of a campfire and accidentally destroyed the solar cell.

"The way we intended for the user to handle it was perhaps not the way the user perceived the object," said Krebs.
Grimshaw said that this field testing is an important part of the design process.

"Such an engagement process is much more likely to improve the uptake of the scientific innovation."

The lamp was developed as part of the 'Lighting Africa' initiative, established by the World Bank, which promotes sustainable lighting solutions for Africa.

Link to article abstract in Energy & Environmental Science

Energy & Environmental Science, doi: 10.1039/b918441d (2010)

http://www.rsc.org/Publishing/Journals/EE/article.asp?doi=b918441d

Energy Environ. Sci., 2010, 3, 512 - 525, DOI: 10.1039/b918441d

En randonnée ou en haute mer, les cellules photovoltaïques enroulables peuvent s'avérer des producteurs d'électricité durables et flexibles. Attachées sur un sac à dos ou un kayak, elles permettent par exemple aux appareils de navigation et de communication de fonctionner indépendamment du réseau électrique. Un groupe de recherche de l'Université de Duisbourg-Essen (UDE) développe actuellement un nouveau concept photovoltaïque. Le Land de Rhénanie du Nord Westphalie et l'UDE soutiennent le projet à hauteur de 1,42 million d'euros pour les 5 prochaines années. L'équipe de recherche, sous la direction de Niels Benson, travaille en particulier sur le photovoltaïque hybride enroulable : "Le besoin en énergie mobile disponible augmente considérablement. Satisfaire à la "fringale énergétique" croissante de façon la plus durable possible est notre objectif."

La plupart des cellules photovoltaïques utilisées actuellement sont constituées de silicium cristallin rigide. La nouveauté est l'utilisation de semi-conducteurs organiques et à base d'oxyde métallique, qui possèdent potentiellement un haut rendement en tant que système purement organique et peuvent aussi être intégrés dans diverses applications mobiles malléables. Selon Benson, "un avantage réside dans le fait que ces substances ne nécessitent pas de hautes températures de fabrication pour utiliser des matériaux porteurs flexibles - une condition importante pour les cellules solaires enroulables".

La création du groupe de recherche renforce l'axe prioritaire de recherche en nanotechnologie et en particulier en génie nanoénergétique de l'UDE, implanté dans le Centre des techniques de nanoénergie (NETZ) et coordonné par le Centre de recherche pour la nanointégration de Duisbourg-Essen (CeNIDE).

- Dr.-Ing. Niels Benson, chef de projet de recherche - Université de Duisbourg-Essen, Forsthausweg 2, D 47057 Duisburg - tél : +49 203/379-1058 - email : niels.benson@uni-due.de
- Dr. Tobias Teckentrup - UDE - tél : +49 203/379-2817 - email : tobias.teckentrup@uni-due.de

Refroidir à l'aide de la lumière du soleil : cette idée, si elle semble paradoxale, se révèle être un concept énergétique original : les chercheurs de l'Institut Fraunhofer des systèmes énergétiques solaires (ISE) à Fribourg étudient l'emploi de l'énergie solaire - déjà utilisée pour la climatisation de bâtiments - pour maintenir au frais les denrées alimentaires périssables comme le lait, le vin ou les fruits. Ils démontrent la viabilité de ce procédé en zone méditerranéenne sur une entreprise de viticulture en Tunisie et une entreprise laitière au Maroc. Dans le cadre du projet MEDISCO (MEDiterranean food and agro Industry applications of Solar COoling technologies), des installations solaires pour la réfrigération du lait et du vin ont été installées en coopération avec des universités, agences de l'énergie et entreprises européennes. Le projet, soutenu par la commission européenne, est coordonné par l'Ecole Polytechnique de Milan.

Peel-and-stamp technique could pave the way for more efficient semiconductors.

An alternative method of making light-sensitive semiconductors could lead to high-efficiency solar cells, better night-vision cameras and a host of other applications, according to research published in this week's issue of Nature¹.

A team led by John Rogers, a materials scientist at the University of Illinois at Urbana-Champaign, has developed a potentially cost-effective technique to produce microchips made of the semiconductor gallium arsenide, which responds well to light. A transfer-printing technique is used to peel and print thin layers of the semiconductor onto glass or plastic, which by overcoming a long-standing problem in gallium arsenide manufacturing could transform the solar-cell industry.

Silicon is the workhorse of the modern semiconductor industry and is used in everything from solar cells to digital cameras. But for decades, scientists have known that when it comes to capturing light, there are better materials out there. Certain types of semiconductors can absorb light much better than silicon, so make better solar cells and infrared-detection devices.

Gallium arsenide is one of the most studied silicon alternatives. It can theoretically convert about 40% of incident solar radiation to electricity, making it twice as effective as silicon. Its efficiency makes gallium arsenide the material of choice for building solar cells for spacecraft.

But like its best applications, the price of gallium arsenide is sky-high. According to Rogers, this is partly because high-quality wafers of gallium arsenide must be grown in carefully controlled chambers. Once grown, the thick wafers are typically sliced up, but only their surfaces are used. Much of the costly material is essentially wasted, says Rogers.

Now Rogers and his colleagues have found another way¹. Rather than growing a single gallium arsenide layer, the team grew a 'pancake' of alternating layers of gallium arsenide and aluminium arsenide. Then, using careful sequence of chemicals the team was able to loosen the individual gallium arsenide layers and peel them off with a silicon-based rubber stamp. They stamped the wafers onto another surface, such as glass or plastic, and then etched the thin slices into circuits using more established techniques.

The team was able to mass-produce very small solar cells, each around 500 micrometres wide, infrared-imaging devices and certain components for mobile phones. Several co-authors on the paper are involved in the start-up company Semprius that aims to use the technique to make gallium arsenide electronics more affordable. "We believe that this kind of approach can be competitive on a cost basis with anything out there," says Rogers, who sits on the company's board of directors.

"What they've done is very impressive," says Gerard Bauhuis, a materials scientist at Radboud University in Nijmegen, the Netherlands. But Bauhuis says that the team's technique can't make circuits that are more than a few-hundred micrometres in size — too small for typical solar cells. More work will need to be done to see whether the peel-and-stamp system can be used to make large sheets, several centimetres square, he says.

Bauhuis, whose lab has its own start-up company called tf2 devices that also aims to produce high-efficiency solar cells, says that gallium arsenide electronics are close to becoming competitive. "In the coming two to five years, it will be decided if this is a feasible route," he says.

Rogers agrees that gallium arsenide shows great potential. His lab is now working on developing solar cells that can generate electricity at around US$1 per watt, which would make it commercially attractive. "We think we can get there," he says, "But it's not really proven until you actually go and do it."

By creating a new type of dye, the researchers, led by Dr Udo Bach of Monash University in Melbourne, have produced a solar cell device that could one day provide a more affordable alternative to non-renewable energy sources.
The findings are reported online in the journal Nature Materials.
The team, involving scientists from Monash University, the University of Wollongong and Germany's University of Ulm, are the first to succeed in making 'stacked printable' solar cells work together to generate more power.
Currently, printable solar cells can't capture as much of the sun's energy as traditional solar cells on the market.
But the fact that they can be printed onto thin polymer means they're extremely cheap to make, and with further development could be used on a variety of surfaces, including water, says Bach.
"Increasing the efficiency of these cells even slightly will make them a competitive alternative to heavy, expensive solar panels."

Working together

"Generally you can increase the efficiency of any solar device by creating stacks of cells and putting them on top of each other, like a sandwich," says Bach.
But putting two printable solar cells together results in them cancelling each other out, unless one of the cells is inverted, he adds.
Until now, the problem was that the inverted printable solar cells hadn't been efficient enough to create a high power device.
By developing a new type of dye for these inverted cells, Bach and his team have shown for the first time that the efficiency of the stacked cells can exceed that of the cells on their own.
"We've managed to show that tandem structures can occur with high efficiency, previously people had only shown that they worked," says Andrew Nattestad of Monash University, who also worked on the project.
"Although they're still a lot less efficient than silicon solar cells, it's estimated they could be around a quarter of the cost," he adds.

First step

Le Solar Impulse HB-SIA, un avion solaire visant à voler nuit et jour sans carburant, a réalisé pour la première fois un vol d'environ 350 mètres, jeudi à 13h11.

Faisant suite aux essais au sol effectués ces dernières semaines, qui ont permis de vérifier bon nombre de paramètres (contrôlabilité du prototype, distance d'accélération et de freinage, puissance de propulsion), le pilote d'essai, Markus Scherdel a pu faire accélérer le prototype jusqu'à sa vitesse de décollage.

Alors que l'appareil prenait doucement de la vitesse, l'immense aile du Solar Impulse s'est progressivement soulevée avant d'assurer un vol d'environ 350 mètres, à un mètre d'altitude et pour enfin se reposer au centre de la piste.

"D'un côté, je trouve extraordinaire de voir un rêve se réaliser. Cela fait plus de dix ans maintenant que j'ai imaginé un avion solaire pouvant voler jour et nuit sans carburant pour promouvoir les énergies renouvelables. Et aujourd'hui, notre équipe a fait décoller cet avion pour la première fois. C'est un grand moment ! D'un autre côté, je mesure avec humilité la difficulté du chemin qu'il reste à parcourir entre les premiers tests et le tour du monde !", a commenté Bertrand Piccard, initiateur et président de Solar Impulse.

Le Solar Impulse a effectué son premier vol miniature

"C'est l'aboutissement de 6 ans du travail intense de toute une équipe ! Ce premier décollage clôture avec succès la première étape de Solar Impulse et confirme nos choix techniques. Nous sommes maintenant prêts à démarrer une nouvelle phase, celle des tests en vol !", a déclaré André Borschberg, co-fondateur et CEO de Solar Impulse.

A ce stade les panneaux solaires n'étaient pas encore connectés. Ce premier décollage réussi, le Solar Impulse HB-SIA sera démonté et transporté sur l'aérodrome de Payerne (VD). Dès début 2010, l'avion fera ses premiers vols d'essai solaires et accomplira des missions de plus en plus longues jusqu'à effectuer le premier vol de nuit à l'énergie solaire.

Solar energy could greatly improve standard of living in poor households in India / Women and children benefit most

Solar energy has the potential to improve the living conditions of poor rural households in India as well as contribute to the country’s future energy security, according to Professor Govindasamy Agoramoorthy from Tajen University, who is Tata-Sadguru Visiting Chair, and Dr. Minna Hsu from the National Sun Yat-sen University in Taiwan. Their study¹, looking at the benefits of solar lanterns on the livelihoods of village communities in Western India, as well as sustainable use of the environment, has just been published online in Springer’s journal Human Ecology.

In India, approximately 70 percent of rural areas lack electricity and over 60 percent of rural households use kerosene lamps for lighting. Kerosene lamps are not only expensive, they are also inefficient, potentially dangerous and a major source of greenhouse gases. Interestingly, the average number of sunny days in India ranges from 250 to 300 days a year, with a solar energy equivalent greater than the country’s total energy consumption. Energy efficiency is critical to nations such as India with large and growing populations. Solar lanterns, which make the most of the country’s natural and abundant sunshine, could be a practical and clean energy alternative to kerosene lamps in village communities.

Sadguru Foundation, a non-profit agency specializing in natural resources management in India, supplied 100 solar lanterns to socially and economically disadvantaged households in 25 villages in the Dahod District of the Gujarat State between January 2004 and December 2007. Agoramoorthy and Hsu studied the effects of using solar lanterns on energy usage, household savings in terms of kerosene and electricity costs, as well as the family’s quality of life. The women in the households were interviewed a month before and again a month after the introduction of the solar lanterns.

Overall, expenditure on kerosene and electricity dropped significantly in all households, after the solar lanterns were introduced. On average each household made important savings ranging from 150 to 250 US dollars annually. Whereas both households above and below the poverty level used a similar amount of electricity before the lanterns were introduced, after their introduction households below the poverty level used significantly less electricity than those above the poverty level.

The researchers also found that the solar lanterns particularly benefited school-aged children and women. Although 70 percent of the villages are connected to the power grid, they do not receive power early in the morning or in the evening because the state power company redirects electricity to major towns and cities. However, with the six hours of light supplied daily by the solar lanterns, study hours increased which had a positive influence on the children’s performance at school. Women were also able to perform their routine household work both indoors and outdoors during power outages.

The authors conclude that “the use of solar energy will contribute to India’s future energy security, particularly in rural areas where the technology that converts sunlight directly into electricity offers a decentralized alternative to uncertain electricity supplies. If implemented efficiently, renewable energy projects could not only improve the quality of life for India’s rural poor but also enhance sustainable use of the environment.”

Reference
1. Agoramoorthy G & Hsu MJ (2009). Lighting the lives of the impoverished in India’s rural and tribal drylands. Human Ecology; DOI 10.1007/s10745-009-9224-7

The full-text article is available to journalists as a pdf.

Contact:
Ana Granadillo Markl
tel +49-6221-487-8414

Enerzine a évoqué mardi, le projet Photosil du CEA-Liten, un silicium à bas-coût. Un autre axe de recherche pour le CEA vise également la production d’énergie solaire à partir de films en polymère.

Vers un film solaire flexible, léger et transparent

L’utilisation de semi-conducteurs organiques, autrement dit en plastique, peut apporter aux cellules PV une grande souplesse d’utilisation tout en réduisant les coûts de production. En contrepartie, cette technologie n’offre que des rendements faibles, de l’ordre de 5%, et se dégrade rapidement (durée de vie de quelques centaines d’heures environ), ce qui limite dans un avenir proche leur accès à quelques marchés de niche, tels que celui de l’électronique nomade.

Malgré ces points faibles, on peut imaginer à plus long terme des applications presque infinies : le matériau photosensible peut en effet s’étaler sous forme liquide. En utilisant des techniques d’impression grande surface jet d’encre, on pourrait imaginer des « films » polymères solaires de quelques 200 nm d’épaisseur en mesure de recouvrir de plus grandes surfaces.

Les principaux axes de recherche du CEA à l’INES visent à améliorer le rendement ainsi que la durée de vie des cellules en les protégeant des agressions extérieures. Le CEA-Liten cherche également à développer une technique d’impression par jet d’encre qui permettrait de traiter aisément de grandes surfaces.

Les rendements de conversion obtenus ont connu une progression spectaculaire (3,4% sur substrat de verre fin 2004, 4,75% en 2007, puis 5,2% en mars 2008). Ce dernier résultat positionne les équipes du CEA à l’INES au meilleur niveau mondial, parmi les quelques laboratoires qui ont réussi à atteindre la barre des 5%. Sur substrat plastique, les rendements s’élèvent à 4% pour le format standard (0,28 cm2) et à 3,3% pour un module de quatre cellules de 12 cm2. Le procédé d’élaboration a également gagné en fiabilité.

La priorité est maintenant d’accroître la durée de vie de ce type de dispositif. Celle-ci est directement liée à la qualité de l’encapsulation. Des accords de fourniture de nouvelles solutions d’encapsulation ont été signés avec deux industriels en pointe dans ce domaine avec de premiers résultats encourageants.

4/4 un nouveau modèle de chauffe-eau solaire en cours de préparation
http://www.bulletins-electroniques.com/actualites/58398.htm

Une équipe composée d'enseignants et d'étudiants du département de génie mécanique à l'Université Kun Shan à Taiwan a développé un nouveau dispositif de chauffe-eau solaire [1] qui suit le mouvement du Soleil par rapport à la Terre. Ce dispositif augmente non seulement l'efficacité du chauffe-eau mais est également en mesure de chauffer l'eau jusqu'à 50 degrés Celsius. La viabilité commerciale de ce chauffe-eau est actuellement à l'essai.

Les chauffe-eau solaires actuels fonctionnent avec des panneaux solaires traditionnels qui sont des écrans plats fixés dans une certaine position. La lumière du soleil ne peut pas être capturée à certains angles, même en plein jour. Le dispositif présenté par CHEN Chang-Jen, coordinateur du projet, est basé sur un nouveau système de suivi du tracé du Soleil qui permet de capturer la lumière du Soleil de manière optimale en ajustant l'angle d'inclinaison des panneaux réflecteurs. Il conduit, selon CHEN, à une efficacité trois fois plus élevée que les panneaux solaires traditionnels.

YEN Tze-Che, un des étudiants impliqués dans le projet, affirme que des instruments de précision ont été installés au dernier étage du département de génie mécanique, afin de recueillir des données sur l'efficacité du chauffe-eau. Les résultats préliminaires sont très positifs, mais le chauffe-eau est toujours en phase de test. Plusieurs industriels ont d'ores et déjà contacté le département afin de discuter de la commercialisation de ce nouveau chauffe-eau solaire qui, en cas de succès, pourrait finalement devenir équipement courant des ménages.

Un nouveau type de concentrateur solaire à base d'acrylique et appelé "Light-Guide Solar Optic" (LSO) pourrait diminuer de manière significative le coût de production d'électricité à partir du soleil.

Contrairement aux modèles existants, il n'est pas nécessaire d'utiliser des miroirs, des optiques complexes ou autres produits chimiques à manipuler pour piéger la lumière. "C'est de la pure optique géométrique", a indiqué Nicolas Morgan, le directeur du développement des affaires à Toronto.
Un concentrateur solaire hybride : acrylique / verre

Un concentrateur solaire hybride : acrylique / verre

L'optique de haute précision - une partie en acrylique et une autre en verre - est moulée de telle sorte que la lumière piégée rebondit en son centre. Un deuxième verre optique concentre la lumière de 1 000 soleils et la dirige vers un petite cellule solaire à haut rendement. La conception permet de réduire à la fois le coût de fabrication et de transport.

Contrairement à d'autres concentrateurs, la lumière ne quitte pas l'optique avant d'atteindre la cellule solaire. "C'est une question de contrôle de l'angle critique, une fois que la lumière pénètre dans la première optique", explique Nicolas Morgan.

La conception profite d'un phénomène appelé "complète réflexion interne", à partir d'un angle duquel un faisceau de lumière entrant dans un matériau optique se réfléchit plutôt que d'être absorbé.

Mais comme d'autres concentrateurs PV, la technologie solaire de Morgan a encore besoin d'un système de suivi (Tracker) pour faire face au soleil en permanence.

Le chercheur espère que la société sera en mesure de construire un système pour moins de 1 $ par watt à partir de 2011. Cela conduirait à un produit d'une efficacité d'environ 30 %, à des coûts compétitifs par rapport à la technologie du solaire à couche mince.

5/3 un nouveau matériau pour des cellules solaires plus efficaces et des circuits plus flexibles

Des physiciens de l'université de Rutgers ont découvert une propriété électronique inhabituelle dans un matériau qui aurait le potentiel d'améliorer l'efficacité des cellules solaires et le design des puces informatiques.

Les chercheurs ont déterminé qu'un cristal fait en bismuth, fer et oxygène pouvait accomplir des fonctionnalités non accessibles par les semi conducteurs conventionnels. Il agit comme une diode réversible, qui laisse passer le courant dans une direction sous certaines conditions et dans le sens opposé pour des conditions différentes. Traditionnellement, les diodes ne sont pas réversibles, la direction du courant est fixée lors de la fabrication. Les scientifiques ont aussi découvert que les diodes faites dans ce matériau génèrent du courant lorsqu'elles sont exposées à la lumière, faisant de ce matériel un candidat potentiel pour les futures cellules solaires. Ce matériau apparaît comme très sensible à la lumière dans le domaine du bleu.

Le matériau étudié appartient à la classe des matériaux ferroélectriques ce qui signifie qu'il possède une polarisation électrique à l'état spontané. Cette polarisation, qui d'après les chercheurs contrôlerait la capacité du cristal d'agir comme une diode, est connu pour être du type "bulk effect" une caractéristique qui fait intervenir l'ensemble du cristal. Alors qu'au contraire, les semi conducteurs traditionnels agissants comme une diode, sont basés sur des effets électriques situés aux interfaces d'une jonction p-n. Ce matériel appartient également à la classe des matériaux cristallins pérovskites [1].

Selon Sang-Wook Cheong [2], "Ceci pourrait rendre le design des circuits électriques plus souples. Les ingénieurs pourraient concevoir un seul élément de circuit qui, sous une certaine configuration donnerait une fonction particulière puis, en changeant la configuration, on obtiendrait une fonction différente".

L'équipe a publié un papier dans le magazine Science Express et projette de publier un article plus conséquent dans un des prochains numéros du magazine Science. Cependant certaines applications pourraient être limitées car le bismuth est un métal dont tous les sels et les vapeurs sont toxiques et est interdit en France depuis 1974. C'est également un sous-produit de l'extraction du plomb, du cuivre, de l'étain, de l'argent et de l'or ce qui implique des ressources en minerai exploitable restreintes.

[2] Sang-Wook Cheong, physics professor in the School of Arts and Sciences

Tenesol et la société Canevaflor, leader français des murs végétalisés dépolluants ont imaginé un mur végétal, équipé de panneaux solaires photovoltaïques, capable de produire une électricité qui sera convertie et réinjectée sur le réseau électrique.

Le mur végétal dépolluant imaginé par Canevaflor proposait déjà trois atouts environnementaux :

l’isolation thermique, l’isolation phonique et le traitement de l’air. Valeurs ajoutées auxquelles il faut maintenant ajouter l’intégration des panneaux solaires Tenesol, et tous les avantages induits par le solaire photovoltaïque.
« Nous sommes très heureux d’associer Tenesol à Canevaflor, et d’avoir créé ensemble le « Garden and Sun », qui combine des qualités esthétiques et technologiques hors du commun », commente Benoît Rolland, Directeur Général de Tenesol.

Tenesol a développé une expertise dans le domaine de l’énergie solaire sur les 5 continents, à travers environ 14 000 réalisations. Depuis sa création, Tenesol a installé plus d’un million de mètres carrés de panneaux solaires !

Le consortium VICOSC* en partenariat avec le centre de recherche australien (CSIRO **), espère bien accroître la flexibilité, la surface, et le rapport coût-efficacité de l'impression des cellules solaires flexibles organiques.

Le ministre de l'Énergie et des Ressources de l'Etat du Victoria, Peter Batchelor (à gauche sur l'image), a annoncé hier le lancement de tests d'impression par Securency International, une société d'impression de billets de banque. "La production de ces films solaires sera aussi simple que l'impression de billets", a indiqué M. Batchelor.

"Cette technologie de pointe offre des avantages sur celle du solaire traditionnel en raison de la possibilité de produire des cellules solaires à moindre coût et de les installer sur de vastes superficies, comme les toits".

"La technologie utilisée pour ces cellules n'en n'est encore qu'à ses débuts, mais ce projet vise à en accélérer le développement et à l'appliquer aussi rapidement que possible."

Une liaison maritime régulière entre le Vieux-Port de La Rochelle et le Port de plaisance des Minimes va s'ouvrir dès le mois d’avril avec le premier bus de mer électrosolaire totalement intégré aux transports publics.

Un deuxième bateaux est en construction et sera opérationnel à partir de mai.

Les bus de mer sont les premiers navires de transport de passagers à propulsion électrosolaire, de grande capacité (jusqu’à 75 personnes) capables de naviguer en mer dans des conditions de vagues, de courant et de vent.

Le "Copernic" et son jumeau le "Galilée" remplaceront deux navires à moteur diesel qui transportent annuellement 200 000 passagers sur une distance de 5 km.

Ces deux catamarans fabriqués en matériaux composites ont été étudiés pour une consommation minimale d'énergie. Leur consommation pour 100 km parcourus a été évaluée à 7 euros par jour, soit six fois moins qu'un navire à propulsion classique.

Les panneaux photovoltaïques, installés sur leurs toits fournissent 20 % de l'énergie utile au bateau. Les 80 % restant proviennent de batteries nickel cadmium qui sont rechargées chaque soir.

Le "Copernic" a suffisamment d'autonomie pour réaliser 15 rotations journalières.

Entech Solar a développé un nouveau type de panneau solaire qui peut non seulement produire de l'électricité mais également faire office de chauffe eau.

Il s'agit d'un développement pour le moins étonnant, car avec la même surface de travail, le ThermaVolt a la capacité de convertir la lumière du soleil en deux formes d'énergie pour une plus grande efficacité.

L'aspect intéressant de la technologie d'Entech reste la lentille de Fresnel réalisée en matière plastique, qui va concentrer 20 fois la lumière du soleil sur les cellules solaires en silicium.
Lors de l'assemblage, les cellules solaires sont électriquement isolées et encapsulées. Le système utilise un appareil optique appelé "prisme couvert" pour booster les performances. Un liquide isotherme refroidi le radiateur et permet la collecte des résidus de chaleur issus des cellules solaires.

Un panneau solaire à double fonctions d'Entec Solar

Ce double fonctionnement ne sera pas proposé pour le marché du résidentiel. Le coût de revient a été estimé entre 6 et 7 dollars par watt.

12/12 Un projet à la dimension parabolique - le ciel ne vient-il pas ainsi au secours de la Terre ? -,

Inaugurés mercredi dernier par le pape Benoît XVI, ces 2 400 panneaux solaires installés sur le toit de la salle Paul-VI vont contribuer à faire de la cité vaticane l’un des États les plus neutres du monde en matière d’émissions de gaz carbonique. Ils permettront en effet d’économiser quelque 80 tonnes de pétrole chaque année, tout en répondant aux préoccupations écologiques que Benoît XVI ne cesse d’afficher dans ses discours. Un projet à la dimension parabolique - le ciel ne vient-il pas ainsi au secours de la Terre ? -, qui présente également l’avantage de ne rien coûter : il s’agit d’un cadeau offert par le fabricant, en échange d’une bénédiction visant à réduire… les vols dans son entreprise.

Des chercheurs du MIT ont développé un nouveau modèle de cellules photovoltaïques et ont ainsi réussi à augmenter fortement la puissance fournie habituellement. Les nouvelles cellules sont composées d'une fine couche de silicium comprise entre une couche anti-reflet sur le dessus, et d'une nouvelle combinaison de multi couches réfléchissantes associée à un réseau de diffraction en dessous. Les résultats obtenus ont montré qu'il était possible d'augmenter jusqu'à 50% le courant de sortie.

Les multicouches déposées sur le dessous de la cellule permettent à la lumière de rebondir plus longtemps dans la couche fine de silicium, lui donnant ainsi suffisamment de temps pour transmettre son énergie à la structure et produire un courant électrique. Selon Peter Bermel un chercheur du laboratoire d'électronique du MIT (MIT's Research Laboratory of Electronics): "Sans ce revêtement, la lumière sortirait directement dans l'air, en dehors de la structure". Toujours selon Bermel "Il est primordial d'assurer que tout rayon qui entre dans la couche parcours un long trajet dans le silicium. Le problème est de connaître la distance minimale parcourue par la lumière dans le silicium avant qu'il y ait une forte probabilité qu'elle soit absorbée" de façon à produire un courant électrique.

L'équipe a débuté son étude en lançant des milliers de simulations informatiques, jouant sur plusieurs paramètres comme l'espace entre les lignes du réseau de diffraction, l'épaisseur de silicium, le nombre de multicouches de réflexion déposé sur la surface du dessous. Ceci afin d'optimiser l'efficacité du modèle. Selon le Prof. Lionel Kimerling, le rofesseur en sciences des matériaux qui dirige le projet "les résultats simulés sont nettement meilleurs que n'importe qu'elle autre structure. Ainsi pour une fine pellicule de 2 micromètres de silicium, une augmentation d'efficacité de 50% a été mesurée lors de la conversion des rayons solaires en électricité". "Les expériences ont confirmé les prévisions, et les résultats obtenus ont déclenché un considérable intérêt industriel. Si le marché du solaire reste fort, une mise sur le marché dans les 3 ans est possible". Une publication de leur découverte est par ailleurs prévue dans le journal "Applied Physics Letters".

Le potentiel de commercialisation est grand car les substrats de silicium cristallin de haute qualité utilisés dans les cellules solaires habituelles représentent près de la moitié de leur coût. Dans cette nouvelle version ce type de silicium représente une part très faible (environ 1%) de la composition de la cellule. De l'avis de Bermel, grâce à ces recherches le solaire deviendrait une énergie compétitive sur le réseau électrique.

Le projet a été financé par plusieurs partenaires: la chaire Thomas Lord en science et ingénierie des matériaux, l'initiative MIST du MIT, le programme de la NSF consacré aux sciences et l'ingénierie des matériaux of the NSF et la recherche militaire (Army Research Office).

30/11 E: power in the desert: solar towers will harness sunshine of southern Spain

• Andalucia project will power 11,000 homes
• Technology exported to Morocco, Algeria and US

In the desert of southern Spain, 20 miles outside Seville, more than 1,000 mirrors are being carefully positioned. Each is about half the size of a tennis court, so the adjustments will take time. But when they are complete in a few weeks, it will mark a major moment in the quest for renewable energy.

The mirrors are part of the world's biggest solar tower plant, a technology that reflects sunlight to superheat water at a central tower. Once this €80m (£67m) plant is inaugurated in January, it will generate 20MW of electricity, enough to power 11,000 Spanish homes.

Concentrated solar power (CSP) technology, as it is known, is seen by many as a simpler, cheaper and more efficient way to harness the sun's energy than other methods such as photovoltaic (PV) panels. But CSP only works in places with clear skies and strong sunshine.

The Andalucian deserts are an ideal location, and Spain hopes the PS20 plant will enable it to take advantage of its huge solar resource and lead the field in CSP technology.
"The radiation hitting the earth is 10,000 times the consumption of energy," said José Domíngues Abascal, chief technology officer at Abengoa, the Spanish energy company behind the plant. "There is great potential in solar energy."

Abengoa has already built a smaller version of the tower technology to test that the idea works. The 11MW PS10 system has been generating electricity for almost two years. Its new design uses an area larger than 100 football pitches, with 1,255 mirrors, called heliostats, each with a collecting area of 120 sq m. These track the sun as it moves through the day and reflect the energy to the top of a 160-metre tower at the centre of the field. Here, the concentrated light is used to heat water to more than 1000C, producing steam that can turn an electricity generating turbine.

When switched on, the new plant will be the world's largest commercial CSP plant feeding electricity into a national grid. It will be also be a significant step for tower technology, seen as a candidate for the large-scale solar plants of the future.

Spanish firms are charging ahead with CSP: more than 50 solar projects around Spain have been approved for construction by the government and, by 2015, the country will generate more than 2GW of power from CSP, comfortably exceeding current national targets. The companies are also exporting their technology to Morocco, Algeria and the US.

"CSP is at the very beginning of a big boom," said José Luis García, at Greenpeace in Spain. "Spain is in a good position to develop and implement the technology. We have the sun so we are in the best position to lead in this field."

The country's clean energy targets are in line with the EU's plan to source 20% of primary energy from renewables by 2020, which means that 30% of electricity would have to come from carbon-free sources. A new EU renewables directive would increase that electricity target to 40%, but García said Spain could easily reach for more, up to 50%.

John Loughhead, executive director of the UK Energy Research Council, said that Abenoga's tower approach at the new plant was relatively efficient "because what you're doing is concentrating a very large area of sunlight on top of a very small area so you can get very high temperatures".

He added that, given the right environment, solar towers were a credible way to make clean power. "But can you make them cheap enough, will they be reliable enough, will they have the right lifetime?"

Another difficulty for potential developers is cost. In Spain, the generation costs of electricity from CSP are double those from more traditional methods. But Abascal said the price was falling as solar projects got bigger and it would match that of fossil fuel power within a decade.

For now, CSP projects across Spain are built with the promise that the government will pay a premium, known as a feed-in tariff, for any CSP electricity sent into the grid. The PS20 is part of a €1.2bn series of solar power plants based on CSP technologies including tower plants and trough-style collectors - where water is passed in tubes directly in front of parabolic mirrors that collect sunlight - and a few PV panels planned by Abengoa. The solar farm will eventually generate up to 300MW of power, enough for the 700,000 people of Seville, by 2013.

The 20MW solar tower is also a forerunner for an even more ambitious idea, one that Abascal hopes will become a standard for CSP plants in future - a 50MW version that could generate electricity around the clock. "During the day, you'd use 50% of your electricity to produce electricity and 50% to heat molten salt. During the night you use the molten salt to produce electricity."

Molten salt technology is in its early stages but Abengoa is testing the idea at a power plant in Granada. So far the company has demonstrated that it is possible to store up to eight hours of solar energy by heating tanks containing 28,000 tonnes of salt to more than 220C. "This will make it possible to have almost constant production or at least it will be able to produce energy for most of the day," said Abascal.

The European commission has identified CSP as part of its future clean energy technology plan. Earlier this year a representative from its joint research centre argued that CSP could even form a major part of a proposed EU supergrid that would transport electricity, generated in solar plants in southern Europe and northern Africa, across Europe.

The supergrid has received political support from Gordon Brown and France's president, Nicolas Sarkozy, who has commissioned a feasibility study on the project.

Graveyard generation

The Spanish town of Santa Coloma de Gramenet has placed more than 450 solar panels on top of mausoleums at its cemetery to generate power, it emerged yesterday. The crowded, working-class town outside Barcelona decided that flat, open, sun-drenched land was so scarce that the graveyard was the only viable spot to site the panels, which provide enough electricity to power 60 homes. They rest on mausoleums holding five layers of coffins. The idea was a tough sell, said Antoni Fogue, a city council member. But town hall and cemetery officials waged a campaign to explain the project and the panels were erected at a low angle, to be as unobtrusive as possible."This installation is compatible with respect for the deceased and for the families of the deceased," Fogue said.

The world’s most minute solar panel cells have been built and tested and one day in the not too distant future they could be used to power even tinier microscopic machines.

The solar panels were built by Xiaomei Jiang and her team of researchers from the University of South Florida in the States.

Their study published in the Journal of Renewable and Sustainable Energy describes how they built tiny solar panels about the size of a lower case o in 12 point font on a computer.

To make these tiny solar cells the researchers didn’t simply take normal photovoltaic solar panels – the kind you might see on rooftops – and make them much smaller.

Regular solar panels are built on a brittle backing material made of silicon, similar to the sort of thing computer chips are built on. Instead, these tiny solar cells are based on an organic polymer that has the same properties as silicon, but that can be dissolved into a fluid and printed into a flexible backing material. Theoretically, this organic material could be sprayed on any surface that is exposed to sunlight.

Jiang and her team are developing these tiny panels with the hope that they will one day power a type of microscopic sensor that can be used for detecting dangerous chemicals and toxins.

These detectors are built from carbon nanotubes, the tiny cylinders of carbon that are 50 thousand times thinner than a human hair. The idea is that when the nanotubes are hooked up to a power source of around 15 volts, they can detect small amounts of particular chemicals by measuring the electrical changes that occur when chemicals enter the tubes; the exact change in charge is an indicator of what type of chemical is present.

So far, the team have put together an inch-long array of 20 of these tiny solar cells which has been enough to generate just 7.8 volts. The next step will be to optimize the cells so they produce enough power for the microscopic chemical detectors, which they think they will be able to do in the next generation of solar cells that should be ready by the end of the year.

Construites comme des circuits intégrés, ces cellules photovoltaïques peuvent alimenter des nanomécanismes (MEMS) et ne mesurent qu'un millimètre carré, une surface que les chercheurs sont sûrs de pouvoir diviser par dix.

Les nanotechnologies produisent avec régularité de nouvelles familles de capteurs, pour mesurer pressions et températures ou détecter la présence de substances chimiques dans l'environnement (eau, atmosphère) ou dans le corps humain. Mais il reste un problème à résoudre : l'alimentation électrique. A côté de ces systèmes miniaturisés, à peine visibles à l'œil nu, voire invisibles, la plus modeste des piles bouton est d'un gigantisme incongru. Il faut donc aussi réduire la taille des sources électriques, un objectif que visent de nombreuses équipes.

Celle de Xiaomei Jiang, du Department of Physics (University of South Florida, Tampa, Floride) s'est attelée au cas des cellules photovoltaïques et a utilisé la photolithographie, technique classique de la fabrication de circuits électroniques. Leur cellule mesure seulement 1 millimètre carré et le prototype réalisé en contient 20, occupant 2,2 centimètres carrés. L'anode est constituée d'un oxyde métallique (alliage d'étain et d'indium), avec une cathode d'aluminium. Entre les deux est installée la couche dite active, c'est-à-dire photosensible. Elle est composée de l'association désormais considérée comme la plus prometteuse pour les cellules photovoltaïques, de deux molécules organiques, le P3HT et le PCBM.

Le premier est un polymère organique (polyhexylthiophène) et le second (ester méthylique d'acide butyrique) est un dérivé du fullerène (molécule de forme sphérique comportant 60 atomes de carbone). Ces deux composés forment ce que l'on appelle une hétérojonction, c'est-à-dire une jonction entre deux matériaux semi-conducteurs différents. Dans ce couple, le P3HT est un donneur d'électrons et le PCBM un accepteur.

Sous un éclairage standardisé (dit AM 1.5 dans le domaine des cellules photovoltaïques) de 132 mW/cm², ce réseau de vingt cellules fournit 55 microampères avec une tension de 7,8 volts. On est très loin des besoins du plus économe des baladeurs mais cette modeste production peut suffire à des MEMS (Micro-Electro-Mechanical Systems), des systèmes micromécaniques réalisés avec les techniques de microgravure utilisées pour la confection des circuits électroniques et comportant un ou plusieurs éléments mobiles. Servant de capteurs ou d'actionneurs, ils fonctionnent à l'électricité mais en réclament très peu.

Dans la revue The Journal of Renewable and Sustainable Energy (JRSE), les auteurs de l'étude affirment que la technique mise au point permettrait de réaliser des réseaux de cellules de 0,01 millimètre carré. L'équipe s'emploie maintenant à concrétiser cette promesse mais aussi à augmenter la tension électrique fournie.

Réduit à une taille minuscule, un dispositif comportant un ou plusieurs MEMS et un tel capteur solaire serait complètement autonome pourvu qu'il ait un peu de lumière, provenant du soleil ou d'éclairages artificiels. Pour contrôler la qualité de l'air ambiant, détecter une molécule toxique ou effectuer différentes mesures, il suffirait alors d'un appareil plus petit qu'un confetti.

Une équipe de chercheurs chinois s'apprête à publier les résultats de leurs recherches, qui promettent une avancée importante dans la réalisation de cellules solaires à faible coût.

Les recherches de l'équipe du professeur Wang Peng, de l'Académie chinoise de Sciences, se sont portées sur les cellules de Grätzel, du nom de leur inventeur suisse Michael Grätzel.

Le principe général de la cellule photo électrochimique à colorant, la cellule Grätzel, est de placer entre deux plaques de verre un colorant, relié à des électrodes transparentes. Le procédé a recours à l'oxyde de titane, moins onéreux que le silicium utilisé dans les cellules solaires conventionnelles. Ce procédé est comparé au processus naturel de la photosynthèse.

Les cellules de Grätzel promettent de réduire jusqu'à 5 fois les coûts actuels des panneaux solaires, et offrent d'autres avantages, comme la possibilité d'être appliquées sur des surfaces souples, voire sur des surfaces transparentes, et d'être utilisables des deux côtés.

En revanche, elles souffrent de deux inconvénients majeurs : un vieillissement rapide et une efficacité insuffisante.
Après exposition à de hautes températures, ce type de cellule perd en effet un grande partie de son efficacité. Un point sur lequel l'équipe de Wang Peng, en collaboration avec Michael Grätzel, a réalisé une avancée majeure : après 1 000 heures d'exposition en plein soleil, leur nouveau modèle conserve plus de 90% de sa capacité de conversion.

Les chercheurs ont également mis au point un nouveau type de colorant, à base de ruthénium, qui stimule les capacités de captation de la lumière. Leur procédé a fait la preuve d'un efficacité de l'ordre de 10%, un record pour ce type de cellule. Un tel rendement à faible coût pourrait ouvrir la voie à une plus grande accessibilité de la production d'énergie solaire, espèrent-ils.

Le détail de leur recherche sera publié le 13 novembre prochain dans le Journal of Physical Chemistry , une publication de l'American Chemical Society.

Improved dyes and electrolytes could make the Grätzel solar-cell design more practical.

Dye-sensitized solar cells, sometimes called Grätzel cells after their inventor, Michael Grätzel, a chemistry professor at the École Polytechnique Fédérale de Lausanne, in Switzerland, have long been considered a promising technology for reducing the cost of solar power. They're potentially cheaper to make than conventional solar cells and can be quickly printed. But this potential hasn't been realized because to achieve efficiency levels high enough to compete with conventional solar cells--about 10 percent--it's been necessary to use volatile electrolytes that need to be carefully sealed inside the cells, an expensive and unreliable step in the manufacturing.

Now Grätzel, along with Peng Wang, a professor at the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, have made efficient solar cells that use nonvolatile electrolytes, with the best achieving efficiencies of 10 percent. They also showed that the solar cells remained stable when exposed to light and high temperatures for 1,000 hours. The advance "pushes the technology close to over the '10 percent hump,' which is where a thin-film technology needs to be to be economically competitive," says Tonio Buonassisi, a professor of mechanical engineering at MIT.

One of the electrolytes is something called an ionic fluid--a fluid largely made up of ions and often composed of salts that have low melting temperatures. An ionic fluid can be used with plastic electrodes, which would allow for solar cells that are both efficient and flexible, and therefore could be incorporated into clothing, awnings, and covers for cars. "We never dreamt that we could have efficiencies of 9 or 10 percent with ionic liquids," Grätzel says. "Ten years ago, we had 1 percent efficiency, and we never thought it would get any better."

The new solar cells were made possible by advances first published this summer. In that work, the researchers increased the conductivity of electrolytes based on ionic fluids and produced solar cells that were 8.2 percent efficient. In the current work, published last month in the Journal of Physical Chemistry, the researchers further increased the efficiency by pairing the ionic liquid electrolyte with a new dye, the part of the dye-sensitized solar cell that absorbs sunlight. The new dye absorbs light far better than the conventional dye. Because the dye absorbs light so well, it's possible to cut the thickness of the active material in the solar cell in half, which makes it easier for electrons to escape the solar cell and reach an external circuit. That, in turn, increases efficiency, in this case to 9.1 percent.

The researchers also paired the new dye with a nonvolatile solvent-based electrolyte. It's not quite as stable as an ionic liquid, and it can't be used with plastic. But it allowed slightly higher efficiencies--up to 10 percent.

Grätzel is working with two companies to commercialize this technology. One, G24 Innovations, based in Cardiff, U.K., is planning to sell dye-sensitized solar cells for applications such as recharging cell phones, especially in countries with unreliable electricity. Another company, Dyesol, based in Queanbeyan, Australia, is planning to sell solar cells that can double as the facades on buildings. Both companies have already developed dye-sensitized solar cells based on earlier technology, but the recent advances could make the cells cheaper and significantly improve performance.

11/11 USA: Solar power game-changer: 'near perfect' absorption of sunlight, from all angles
http://news.rpi.edu/update.do?artcenterkey=2507

Researchers at Rensselaer Polytechnic Institute have discovered and demonstrated a new method for overcoming two major hurdles facing solar energy. By developing a new antireflective coating that boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire solar spectrum from nearly any angle, the research team has moved academia and industry closer to realizing high-efficiency, cost-effective solar power.

A new antireflective coating developed by researchers at Rensselaer could help to overcome two major hurdles blocking the progress and wider use of solar power. The nanoengineered coating, pictured here, boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire spectrum of sunlight from any angle, regardless of the sun’s position in the sky.

“To get maximum efficiency when converting solar power into electricity, you want a solar panel that can absorb nearly every single photon of light, regardless of the sun’s position in the sky,” said Shawn-Yu Lin, professor of physics at Rensselaer and a member of the university’s Future Chips Constellation, who led the research project. “Our new antireflective coating makes this possible.”

Results of the year-long project are explained in the paper “Realization of a Near Perfect Antireflection Coating for Silicon Solar Energy,” published this week by the journal Optics Letters.

An untreated silicon solar cell only absorbs 67.4 percent of sunlight shone upon it — meaning that nearly one-third of that sunlight is reflected away and thus unharvestable. From an economic and efficiency perspective, this unharvested light is wasted potential and a major barrier hampering the proliferation and widespread adoption of solar power.

After a silicon surface was treated with Lin’s new nanoengineered reflective coating, however, the material absorbed 96.21 percent of sunlight shone upon it — meaning that only 3.79 percent of the sunlight was reflected and unharvested. This huge gain in absorption was consistent across the entire spectrum of sunlight, from UV to visible light and infrared, and moves solar power a significant step forward toward economic viability.

Lin’s new coating also successfully tackles the tricky challenge of angles.

Most surfaces and coatings are designed to absorb light — i.e., be antireflective — and transmit light — i.e., allow the light to pass through it — from a specific range of angles. Eyeglass lenses, for example, will absorb and transmit quite a bit of light from a light source directly in front of them, but those same lenses would absorb and transmit considerably less light if the light source were off to the side or on the wearer’s periphery.

This same is true of conventional solar panels, which is why some industrial solar arrays are mechanized to slowly move throughout the day so their panels are perfectly aligned with the sun’s position in the sky. Without this automated movement, the panels would not be optimally positioned and would therefore absorb less sunlight. The tradeoff for this increased efficiency, however, is the energy needed to power the automation system, the cost of upkeeping this system, and the possibility of errors or misalignment.

Lin’s discovery could antiquate these automated solar arrays, as his antireflective coating absorbs sunlight evenly and equally from all angles. This means that a stationary solar panel treated with the coating would absorb 96.21 percent of sunlight no matter the position of the sun in the sky. So along with significantly better absorption of sunlight, Lin’s discovery could also enable a new generation of stationary, more cost-efficient solar arrays.

“At the beginning of the project, we asked ‘would it be possible to create a single antireflective structure that can work from all angles?’ Then we attacked the problem from a fundamental perspective, tested and fine-tuned our theory, and created a working device,” Lin said. Rensselaer physics graduate student Mei-Ling Kuo played a key role in the investigations.

Typical antireflective coatings are engineered to transmit light of one particular wavelength. Lin’s new coating stacks seven of these layers, one on top of the other, in such a way that each layer enhances the antireflective properties of the layer below it. These additional layers also help to “bend” the flow of sunlight to an angle that augments the coating’s antireflective properties. This means that each layer not only transmits sunlight, it also helps to capture any light that may have otherwise been reflected off of the layers below it.

The seven layers, each with a height of 50 nanometers to 100 nanometers, are made up of silicon dioxide and titanium dioxide nanorods positioned at an oblique angle — each layer looks and functions similar to a dense forest where sunlight is “captured” between the trees. The nanorods were attached to a silicon substrate via chemical vapor disposition, and Lin said the new coating can be affixed to nearly any photovoltaic materials for use in solar cells, including III-V multi-junction and cadmium telluride.

Along with Lin and Kuo, co-authors of the paper include E. Fred Schubert, Wellfleet Senior Constellation Professor of Future Chips at Rensselaer; Research Assistant Professor Jong Kyu Kim; physics graduate student David Poxson; and electrical engineering graduate student Frank Mont.

Funding for the project was provided by the U.S. Department of Energy’s Office of Basic Energy Sciences, as well as the U.S. Air Force Office of Scientific Research.

Contact: Michael Mullaney
Phone: (518) 276-6161
E-mail: mullam@rpi.edu

In a significant milestone in the deployment of flexible, printed photovoltaics, Konarka, a solar-cell startup based in Lowell, MA, has opened a commercial-scale factory, with the capacity to produce enough organic solar cells every year to generate one gigawatt of electricity, the equivalent of a large nuclear reactor.

Organic solar cells could cut the cost of solar power by making use of inexpensive organic polymers rather than the expensive crystalline silicon used in most solar cells. What's more, the polymers can be processed using low-cost equipment such as ink-jet printers or coating equipment employed to make photographic film, which reduces both capital and manufacturing costs compared with conventional solar-cell manufacturing.

The company has produced its cells in a relatively small pilot plant with the capacity of creating about one megawatt of solar cells a year. The large gigawatt capacity of the plant was made possible by the fact that Konarka does not require specialized equipment to make its solar cells. Indeed, the factory and equipment were formerly owned by Polaroid and used to make film for medical imaging. With minor modifications, the same equipment can now be used to make solar cells. Richard Hess, Konarka's president and CEO, says that the company's ability to use existing equipment allows it to scale up production at one-tenth the cost compared with conventional technologies.

Unlike conventional solar cells, which are packaged in modules made of glass and aluminum and are rigid and heavy, Konarka's solar cells are lightweight and flexible. This makes them attractive for portable applications. What's more, they can be designed in a range of colors, which can make them easier to incorporate attractively into certain applications. One of the first products to use Konarka's cells will be briefcases that can recharge laptops. Another company is testing Konarka's solar cells for use in umbrellas for outdoor tables at restaurants. They could also be used in tents and awnings.

The solar cells are based on a design by Alan Heeger, a professor of physics at the University of California, Santa Barbara, who won the Nobel Prize in 2000 for his work helping to develop electrically conducting polymers. His solar-cell design included two main components: a polymer that releases electrons when exposed to sunlight, and carbon nanostructures called fullerenes, which escort those electrons away from the polymers and to an external electronic circuit, generating electricity. Konarka's solar cells use similar polymers and fullerene-like nanostructures. These materials, as well as positive and negative electrodes made from metallic inks, can be spread over a sheet of plastic using printing and coating machines to make solar cells.

However, the technology has several drawbacks that will initially limit its applications. The solar cells only last a couple of years, unlike the decades that conventional solar cells last. What's more, the solar cells are relatively inefficient. Conventional solar cells can easily convert 15 percent of the energy in sunlight into electricity; Konarka's cells only convert 3 to 5 percent. As a result, they require much more area to generate electricity, so they're not as attractive as ordinary solar cells for generating electricity on rooftops, where space is limited and the technology's light weight and flexibility aren't needed, says Dana Olson, a research scientist at the National Renewable Energy Laboratory, in Golden, CO.

At first, Konarka will focus on niche applications such as umbrellas and tents, while working to increase the efficiency of the solar cells to between 7 and 10 percent, at which point the company could compete in cost with conventional sources of electricity, Hess says.
The company plans to gradually ramp up production at its new factory, reaching full capacity in two to three years. Because the solar cells can be made transparent, Konarka is also developing a version of its solar cells that could be laminated to windows to generate electricity and serve as a window tinting.

28/10 NL: PEERS+ invente les vitres réglant et convertissant la lumière du soleil

http://www.bulletins-electroniques.com/actualites/56297.htm

La jeune entreprise néerlandais Peer+, issue de l'Université technique d'Eindhoven, a su exploiter les exigences actuelles de durabilité et d'économie d'énergie en créant des vitres qui s'adaptent aux besoins de lumière et de chaleur des personnes présentes dans une pièce. Elles se teintent quand la lumière du soleil apporte trop de chaleur dans la pièce, réduisant ainsi l'usage du climatiseur, et à l'inverse elles deviennent parfaitement transparentes à mesure que la pièce se refroidit, permettant ainsi d'économiser sur le chauffage. Cerise sur le gâteau, elles conservent la lumière du soleil surabondante et la transforment en électricité.

Deux techniques différentes ont dû être étudiées et associées pour réaliser ce vitrage intelligent, appelé Smart Energy Glass : l'utilisation de l'énergie solaire et la technologie d'affichage. La clé est l'enduit en polymère utilisé, qui permet de régler la quantité de lumière captée et réutilisée par la vitre.

Les économies qui découlent de l'utilisation du Smart Energy Glass sont multiples : non seulement l'utilisateur n'a plus besoin de rideaux et de climatiseur, mais il peut également percevoir des subventions lors de la construction d'un immeuble équipé de ce type de vitres écologiques. Certes cela coûte quelques centaines d'euros de plus au mètre carré qu'un vitrage classique, mais par comparaison un panneau solaire revient à près de 600 euros au mètre carré. Au final, en prenant en compte le climatiseur, l'éclairage et la production d'électricité, l'utilisateur économiserait annuellement une dizaine d'euros par mètre carré.

Selon les ingénieurs de Peer+, les débouchés sont nombreux, tels que l'horticulture en serre, l'industrie automobile, les habitations individuelles et surtout les immeubles de bureaux. Pour le moment, Peer+ ne se charge que du développement de l'enduit et laisse la fabrication du verre à d'autres entreprises. Les premières vitres seront commercialisées d'ici 2010

Munich-based Phoenix Solar AG, a German photovoltaic system installer, has committed $615 million (450 million Euros) to purchasing Solyndra's cylindrical solar cells as a core part of its future rooftop installation business. Why? "We see significant cost-savings," says chief technology officer Manfred Bächler. "We simply do not need any supporting structures or ballasts or roof penetrations," because, unlike traditional flat solar panels, the new round kind don't need any help to keep grounded when the wind blows.

In addition, the ability of the solar cylinders to collect direct, diffuse and sunlight reflected from the rooftop-as well as the ability to lay panels of them horizontal to the roof itself means more electricity can be made from a given rooftop. Further, the solar cylinders keep cooler overall, which enhances the performance of the system, Bächler says.

According to Phoenix's tests, the solar cylinders provide an energy yield "competitive with that produced by conventional modules mounted at a 30 degree angle." The thin-film copper-indium-gallium-selenide (CIGS) photovoltaic layer also helps to lower the price so that they're cheaper conventional solar cells made from silicon.

Phoenix will begin installing such rooftop systems on commercial buildings next year, Bächler says: "At the moment, I myself am looking for a suitable roof [on a building] that I can rent to install and operate such a system."

13/10 F: La 1^ère centrale solaire capable de suivre le soleil démarre en Gironde

La première centrale solaire française dotée de "suiveurs" permettant aux panneaux photovoltaïques d'accompagner la course du soleil, avec un rendement supérieur de l'ordre de "20 à 40%", vient de démarrer sa production à Martillac, près de Bordeaux.

La technologie des "suiveurs solaires", ou "trackers", équipe le quart des centrales solaires de grande envergure installées dans le monde, selon Exosun. Cette société girondine a développé le projet de Martillac: une centrale pilote d'une puissance de 100 kilowatt crête (kWc), soit l'équivalent des besoins énergétiques d'une trentaine d'habitations.

Cette centrale électrique solaire, active depuis le 22 septembre, est la propriété d'EDF Energies Nouvelles, filiale d'EDF spécialisée dans la production d'énergie électrique d'origine renouvelable. Elle constitue un "site pilote" pour permettre de "tester cette technologie innovante et capitaliser de l'expérience", explique à l'AFP Marc Frager, directeur France chez EDF Energies Nouvelles.

Occupant une surface de 3.500 m2, elle servira de modèle à une centrale plus ambitieuse -2 mégawatt, soit une puissance vingt fois supérieure- programmée courant 2009 dans les Landes, sur la communauté de communes du Gabardan.

"L'intérêt du suivi solaire, c'est de permettre d'augmenter de 20 à 40% la production d'électricité par rapport à un système fixe", note Daphné de Baritault, chef de produit chez Exosun.

A Martillac, les 126 "suiveurs solaires", équipés chacun de 6 m2 de panneaux photovoltaïques, sont actionnés par des moteurs selon deux axes -est-ouest et nord-sud- pour leur permettre d'être orientés, pendant la quasi-totalité de la journée, à 90 degrés par rapport aux rayons du soleil. Une orientation idéale qui explique un rendement largement supérieur à celui des panneaux fixes.

"L'énergie solaire va supplanter les autres énergies", affirme Frédéric Conchy, président d'Exosun. "C'est une énergie que l'on n'utilise pas assez, alors qu'elle est idéalement répartie et en quantité suffisante. Il faut savoir la capter mais et elle est inépuisable à l'échelle humaine", ajoute-t-il.

"L'économie photovoltaïque représente un fort potentiel en emplois locaux. Aujourd'hui, il y a 43.000 emplois en Allemagne, on est en à 2.500 en France", relève aussi l'entrepreneur girondin.

"Le photovoltaïque est aujourd'hui un de nos axes de développement majeurs dans le monde", confirme Marc Frager pour EDF Energies Nouvelles.

Mais il souligne aussi la nécessité d'un "cadre réglementaire clair et durable pour pouvoir lancer une grande filière industrielle en France". "Les industriels ont besoin de savoir quelles vont être les règles du jeu sur plusieurs années pour pouvoir investir des centaines de millions d'euros dans cette technologie d'avenir", ajoute-t-il.

Integrating solar cells into building materials could make solar power more attractive to homeowners.

Seamless solar: The solar system shown here (darker panels) integrates thin-film solar modules directly into a metal roof. Such systems offer cost savings in labor and materials and blend well with buildings’ designs.

In an effort to promote the adoption of solar technology, United Solar Ovonic of Auburn Hills, MI, has teamed with a major roofing company to create a metal roof system that generates electricity from sunlight. The partnership offers seven different prefabricated systems, ranging in capacity from 3 to 120 kilowatts. Tests show that the solar roof panels are rugged and can withstand winds in excess of 160 miles per hour.

In addition to being more aesthetically pleasing than bulky rooftop-mounted panels, solar roofing materials can cut the cost of household solar installations by doing double duty, generating electricity while protecting buildings from the elements. "Ultimately, if you can use one product to do two things, you can save a lot of money," says Cecile Warner, principal engineer at the National Renewable Energy Laboratory's National Center for Photovoltaics, in Golden, CO.

Building-integrated photovoltaics (BIPV) have been around since the late 1980s, Warner says, but only lately have they begun to see some success with large commercial and residential developments. Recent advances in flexible thin-film photovoltaic materials--such as those sold by United Solar--are allowing manufacturers to more easily integrate photovoltaics directly into the roofs and facades of buildings.

Nonetheless, many builders remain leery of the new technologies. "In the past, people in the construction industry have been burned by trying out new products," Warner says. In particular, she says, they're wary of products that would be difficult to recall should they prove defective. Roofing materials certainly meet that description. "I think that's probably been the sticking point all along," Warner says.

EnergyPeak, the partnership between United Solar and Pittsburgh-based Centria Services Group, is an attempt to allay this skepticism. "We worked with Centria to develop a program that would get our product out to a number of small installers because Centria already has the infrastructure to do this," says Marcelino Susas, vice president of strategic marketing at United Solar's parent company, Energy Conversion Devices, based in Rochester Hills, MI.

When solar companies partner with construction firms, "it gives the product a lot more credibility, and it helps to break down the barrier to adoption," says Warner.

Centria designs and assembles the solar roof systems using United Solar's adhesive thin films, which can simply be peeled off of their backings and stuck to the roofing materials. The company then distributes the final product through small metal-roofing manufacturers that do the installations for building owners and architects. EnergyPeak comes with a 20-year warranty and, depending on the state in which the solar roof is installed, could pay for itself in less than 10 years, Centria says.

Because United Solar's materials are flexible and lightweight, they can be easier and cheaper to install than conventional crystalline-silicon solar cells, and they can be applied to curved roof designs, says Susas. United Solar's amorphous-silicon photovoltaics also perform better than conventional crystalline-silicon solar cells under low light and high temperature, he says.

"BIPV is very interesting because it offsets some of the costs associated with installation and will probably occupy a larger market share of the residential portion of the market," says Michael Locascio, a senior analyst with Lux Research, in New York. "But that portion is very small," he adds. That's because BIPV systems are primarily limited to new home construction or situations in which the owner needs to replace the roof.

And although the adoption of solar power is growing fast, Locascio cautioned that the future of the industry, at least in the United States, is uncertain. The federal Investment Tax Credit, one of the key incentives driving the adoption of solar power in the United States, is set to expire at the end of the year, and it is unclear whether Congress will extend it.

Currently, Europe remains the largest market for BIPV and solar products in general, says Susas. "There are very high incentives for BIPV in Italy and France." For instance, United Solar currently sells its solar laminates to a large asphalt-shingle manufacturer in Italy that supplies residential clients with solar shingles.

Cleaner than clean energy: BioSolar creates new plastic backing forphotovoltaic cells out of cotton and castor beans rather than petroleumproducts

PETROLEUM FREE?: A new backsheet for solar cells, seen at work here, is made from cotton and castor beans rather than petroleum-based plastics.

Solar energy is touted by some as the solution to the world's energy woes.But the process of making the various components requires fossil fuels,both for power and for the components themselves, some of which arebased on petroleum.

A new company, BioSolar, aims to kick petroleum to the curb, at least in the realm of building solar photovoltaics, cells of crystalline siliconthat turn sunlight into electricity. Such photovoltaic cells rely onconventional plastic polymers to provide a protective backing, alsoknown as backsheets. Those plastics are made from—you guessedit—petroleum.

'It's renewable and you don't use any petroleum,' says electricalengineer David Lee, president and CEO of the California-based companyabout the new product. 'The real merit is that we can actually reducethe cost of the backsheet compared to conventional petroleum-basedbacksheet.' Lee claims their backsheets will cost 25 percent less thanconventional backsheets, which cost between $0.70 and $1 per squarefoot.

Already, such backsheets are rising in price, thanks to the recent run-up in world oil costs,at a time when the solar industry is trying to bring down costs to maketheir technology more competitive with other forms of power generation,such as cheap, plentiful and extremely polluting coal.

BioSolar starts with used cotton rags and turns them into a film of cellulose,a natural fiber. They then blend this film with a type of nylon madefrom castor beans by Philadephia-based Arkema, Inc. to make theso-called BioBacksheet. Initial testing by the company at the NationalRenewable Energy Laboratory shows that this flexible plastic backsheetlasts as long or longer than conventional ones, and keeps out just asmuch moisture.

In addition to keeping away from petroleum plastics, BioSolar also claims not to be using any genetically modified cropsin its product—a further boost to its green credibility. But nearly 90percent of the U.S. cotton crop is so altered, either to resistinsects, herbicides or both, according to the U.S. Department ofAgriculture. And cotton cultivation still requires tons of pesticidesand fertilizers, both of which are derived, in part, from petroleum.

Regardless, if the cotton and castor-based backsheet proves cheaperthan the petroleum version it may help remove a bit more fossilsunshine from the new solar energy. 'Our goal is to replace all thepetroleum plastic out of the solar cells with this bio-based one,' Lee says.

By changing the way that conventional silicon solar panels are made, Day4 Energy, a startup based in Burnaby, British Columbia, has found a way to cut the cost of solar power by 25 percent, says George Rubin, the company's president.

The company has developed a new electrode that, together with a redesigned solar-cell structure, allows solar panels to absorb more light and operate at a higher voltage. This increases the efficiency of multicrystalline silicon solar panels from an industry standard of about 14 percent to nearly 17 percent. Because of this higher efficiency, Day4's solar panels generate more power than conventional panels do, yet they will cost the same, Rubin says. He estimates the cost per watt of solar power would be about $3, compared with $4 for conventional solar cells. That will translate into electricity prices of about 20 cents per kilowatt-hour in sunny areas, down from about 25 cents per kilowatt-hour, he says.

Other experimental solar technologies could lead to much lower prices--indeed, they promise to compete with the average cost of electricity in the United States, which is about 10 cents per kilowatt-hour. But such technologies, including advanced solar concentrators and some thin-film semiconductor solar cells, probably won't be available for years. Day4's technology could be for sale within 18 months, the company says.

In conventional solar panels, the silicon that converts light into electricity is covered with a network of silver lines that conduct electrons and serve as connection points for soldering together the individual solar cells that make up a panel. The network consists of rows of thin silver lines that feed into thicker wires called bus bars. Day4 replaces these bus bars with a new electrode that consists of rows of fine copper wires coated with an alloy material. The wires are embedded in an adhesive and aligned on a plastic film. The coated copper wires run on top of and perpendicular to the thin silver lines, connecting them to neighboring cells. The new electrode conducts electricity better than the silver lines, resulting in less power loss. It also covers up less of the silicon than the bus bars, leaving more area for absorbing light.

What's more, the new electrode allowed Day4 to redesign solar cells to absorb more of the solar spectrum and convert this light into electricity more efficiently. Solar cells comprise two layers of silicon. For light to be converted into electricity, it has to pass through the first layer and reach the second. The thinner the top layer, the more light reaches the second layer to be converted into electricity. In a conventional cell, the silver lines are deposited and then heated to high temperatures, which causes the metal to diffuse into the silicon. The top layer must be thick enough that the silver does not diffuse through it and create a short circuit between the layers of the solar cell. By replacing the large bus bars with the new electrode, Day4 was able to make the top layer of the solar cells thinner, increasing the amount of light that can be converted into electricity. Also, since the silver can damage the silicon, replacing it with the new electrode increases the solar cell's power output.

The technology "sounds pretty exciting," says Travis Bradford, a solar-industry analyst with the Prometheus Institute for Sustainable Development, an energy research firm based in Cambridge, MA. The question, Bradford says, is whether the company can translate the latest advances from its lab to large-scale production without increasing costs.

A new roof-mounted system that concentrates sunlight could cut the price of photovoltaics.

A new mechanism for focusing light on small areas of photovoltaic material could make solar power in residential and commercial applications cheaper than electricity from the grid in most markets in the next few years. Initial systems, which can be made at half the cost of conventional solar panels, are set to start shipping later this year, says Brad Hines, CTO and founder of Soliant Energy, a startup based in Pasadena, CA, that has developed the new modules.

Concentrating sunlight with mirrors or lenses on a small area cuts the costs of solar power in part by reducing the amount of expensive photovoltaic material needed. But while concentrated solar photovoltaic systems are attractive for large-scale, ground-based solar farms for utilities, conventional designs are difficult to mount on rooftops, where most residential and commercial customers have space for solar panels. The systems are typically large and heavy, and they're mounted on posts so that they can move to track the sun, which makes them more vulnerable to gusts of wind than ordinary flat solar panels are.

Soliant has designed a solar concentrator that tracks the sun throughout the day but is lighter and not pole-mounted. The system fits in a rectangular frame and is mounted to the roof with the same hardware that's used for conventional flat solar panels. Yet the devices will likely cost half as much as a conventional solar panel, says Hines. A second-generation design, which concentrates light more and uses better photovoltaics, could cost a quarter as much. He says that a more advanced design should be ready by 2010.

The Soliant design combines both lenses and mirrors to create a more compact system. Each module is made of rows of aluminum troughs, each about the width and depth of a gutter. These troughs are mounted inside a rectangular frame and can tilt in unison from side to side to follow the sun. Each trough is enclosed on top with a clear acrylic lid. Inside each trough, a strip of silicon photovoltaic material runs along the bottom. As light enters, some of it reflects off the inside surface of the trough and reaches the strip of silicon. The rest of the incoming light is focused on the strip by a lens incorporated into the acrylic lid.

As a solar concentrating system, this design has a few drawbacks. Because the troughs are mounted close together, they shade each other during parts of the day, decreasing the total amount of electricity produced. They can also only track from side to side, which makes it impossible for them to follow exactly the arc of the sun across the sky. This second problem will be addressed in the second-generation design, in which each trough will be divided into sections, each of which can pivot from side to side and also up and down.

But the ease of installation could help convince solar installers to use the technology, says Craig Cornelius, the technology manager for the Department of Energy's (DOE) solar-energy technology program. DOE recently announced $168 million in funding for 13 solar projects, under which Soliant will receive up to $4 million. Cornelius says that the lower installation costs will help reduce the overall costs of solar power from the modules.

Cornelius thinks that some customers, such as those with plenty of roof space, will opt for cheaper, thin-film solar panels, which in some cases, can doubling as shingles but are less efficient than conventional solar panels. But for those who need more power for the space they have, Cornelius says that Soliant's approach may prove the best option. Its modules produce as much power as conventional flat panels but are less expensive, using 88 percent less silicon. The company's next-generation system would be even better, producing three times as much power per area.

To test the panels, Soliant is working with DOE and Sun Edison, an established solar-system installer and operator based in Beltsville, MD. The second-generation system will be even more challenging to develop because light will be focused on a smaller area, requiring better tracking of the sun. Soliant will also be working with Emanuel Sachs, professor of mechanical engineering at MIT, to improve manufacturing techniques and the system for aiming the concentrators.

http://www.bulletins-electroniques.com/actualites/41611.htm

La firme Acquasol Pty de l'etat du Victoria a annonce son intention de construire la premiere usine solaire de dessalement d'eau de mer du pays, a Point Paterson, non loin de Port Augusta, en Australie Meridionale.

L'usine permettra d'alimenter en eau douce la ville de Port Ausgusta, et a plus long termes, des localites voisines dans un rayon de 200 km.

Actuellement l'eau du fleuve Murray est pompee et acheminee le long de canalisations aeriennes sur une distance de 360 km.

Le complexe produira environ 50 MW a partir du champ solaire et 150 MW a partir de turbines a gaz a cycle combine. L'energie sera generee par un champ de miroirs couvrant une aire de deux kilometres carres.

L'eau salee du golf Spencer sera pompee et purifiee a l'aide d'un procede d'osmose inverse et de distillation thermique multi-effets. Elle produira 5,5 GL d'eau douce par an, une quantite suffisante pour les besoins d'une agglomeration de 34.000 habitants. Les effluents de dessalement ne seront pas rejetes dans l'ocean mais transformes en sel commercialisable, ce qui evitera de polluer le milieu marin.

Le cout global du projet est estime a 370 millions de dollars.

Sources :

14/8 Solar power - in the rain
http://www.guardian.co.uk/g2/story/0,,2144513,00.html

Most of us would love to run our homes on solar power - if only it wasn't so unreliable, cumbersome and expensive. But thanks to a pioneering factory in Wales, those objections may not apply for much longer, says David Adam

If you were hunting for the future of solar power, Wales might not seem the most obvious place to look. Yet in a factory in Cardiff, technology that could finally harness the energy of the sun in an affordable way is quietly rolling off the production line. Such claims may sound familiar. Advocates have talked of the potential of solar power to offer clean and green energy for years, yet the technology has remained stubbornly on the fringes. One reason is the cost. Photovoltaic (PV) solar panels to provide an average home with electricity will set you back about £10,000 to £18,000.

Now those behind the Welsh operation think they may have made a crucial breakthrough. Their solar cell works in a different way from most, and is not based on silicon - the expensive raw material for conventional solar cells. G24 Innovations (G24i), the company making the new cells, says it can produce and sell them for about a fifth of the price of silicon-based versions. At present, it makes only small-scale chargers for equipment such as mobile phones and MP3 players. But it says larger panels could follow - large enough to replace polluting fossil fuels by generating electricity for large buildings.

"This has been at the laboratory stage for 18 years and now we are ready to take it into a huge amount of applications," says Clemens Betzel, president of G24i.

G24i's technology is based on a coloured dye and tiny crystals of titanium oxide - a common pigment in white paint. It exploits a discovery made in 1991 by a Swiss chemist called Michael Graetzel, who found that the combination could be used to copy photosynthesis. When struck by sunlight, the dye spits out an electron, which is immediately captured by the specks of titanium oxide. By collecting the electrons at one side of his new solar cell, and replacing them at the other with an iodide electrolyte solution, Graetzel produced an electric current.

The new so-called Graetzel cells offered a simpler and potentially cheaper way to generate solar power. (Traditional silicon cells are more complicated because they require the generation of an electric field within the silicon to carry away the liberated electrons.) And because they work in a different way, Betzel says the new cells offer other advantages too. They work better in low light levels, including indoors, he says, and they are lighter and less fragile than silicon cells, which are usually mounted on glass or rigid plastic.

At least one big hitter in the renewable energy industry agrees with him: Bob Hertzberg, founder of venture capital firm Renewable Capital, a backer of the G-Wiz electric car, has invested in G24i and talks of it making annual profits of £130m within five years. The company has not yet found a major buyer for its technology, but Betzel says there are some in the wings.

Design students have also been involved with the development process. Earlier this year, the company ran a competition with 45 product design students at St Martin's college of art and design in London, who were asked to think up new uses for the Cardiff solar cells. The winning entries include portable safety lights mounted on life buoys, and lamps to mark scaffolding and hoardings around roadworks and on building sites. They also featured solar-powered security lights, fire exit signs, and window blinds, which could cut electricity use.

The first commercial uses are likely to be in the developing world, where access to electricity is difficult. The firm is working with mobile phone companies including Nokia and Motorola to test whether the G24i cells could charge handsets in rural Africa. For £6-£8, he says, the company can supply a flexible strip of solar cells that can produce 0.4 to 0.5W of power. It's a relatively meagre output, but more than enough for at least 10 minutes of phone calls a day. And that, says Betzel, can make a big difference. "Over two billion people live without access to energy. This isn't about providing expensive, Rolls Royce- quality solutions. It's about improving their quality of life." Similar solar chargers made of silicon cost about £30.

The company believes its technology is also suited to those who work in remote places where access to electricity is unreliable, such as by providing low-cost and lightweight power, lighting and water purification for the disaster relief and emergency services. It is also developing wearable "smart" fabrics, into which the solar cells have been woven, and which could be used to charge connected electronic devices. These can be made in a variety of patterns, the company's PR material notes, including camouflage. Unsurprisingly, the military is another of its target markets.

Jim Watson, deputy director of the Sussex Energy Group at the University of Sussex, is cautiously optimistic about the technology: "It takes a long time for people to take up this kind of technology, but if it works and it's cheap enough, it could play a part."

Watson says solar cell technology is likely to remain targeted at niche applications for the foreseeable future, and is more suited to preventing additional carbon emissions from the proliferation of electronic devices, rather than cutting emissions from existing sources. "What's good about that approach is that it takes renewable technologies into the consumer market, and if they can be presented in that way, they help to get the message across."

In time, G24i envisages companies being forced to "account for their carbon footprint and offset power usage", which it argues its solar technology can help them achieve. Betzel envisages large buildings hanging coloured flexible ribbons of the company's solar cells down the centre of large atria in future. He says there is no reason why the technology couldn't replace PV solar panels on the roofs of homes and other buildings, though the company has not yet proven the longevity of such large versions.

It also claims its technology will "put an end to dead batteries". There is still some way to go - the Cardiff factory's entire annual output of solar cells currently generates just 30MW, about the same as a handful of modern wind turbines (although it plans to expand to 200MW capacity next year). But Betzel insists that solar power is now a viable mass-market future technology. If he is right, then Wales may soon have an unlikely new export.

Région wallonne : convention sur les normes de qualité à appliquer aux équipements solaires

Le secteur de l'énergie solaire a signé, ce mercredi, à Chevetogne une convention avec la Région wallonne sur les normes de qualité à appliquer aux équipements solaires, ainsi que sur l'agrément des installateurs de ces systèmes. Ces normes, qui étaient déjà de mise au préalable au sein de la fédération Belsolar, seront donc désormais codifiées et auront un aspect contraignant, notamment en matière d'octroi de primes.

Sauf à prendre en considération un bilan écologique global, tenant compte des objectifs de Kyoto, ce qui est loin d'être le cas de la majorité des citoyens, l'énergie solaire est encore loin d'être rentable en l'absence des différentes primes régionales, provinciales ou communales. Grâce à celles-ci, le solaire thermique, employé au niveau individuel pour chauffer l'eau des ménages, présente une rentabilité très intéressante. A travers le programme Soltherm lancé en 2000 par le ministre wallon de l'Énergie José Daras dans le cadre du contrat d'avenir, la Wallonie vise l'objectif de 200.000 m2 de panneaux solaires à l'horizon 2010. Un objectif dont on est encore bien loin, avec une moyenne de 5.000 m2 installés chaque année. Des campagnes de promotion vont donc être relancées, tandis que la prime régionale passera d'un peu plus de 600 à 1.500 euros pour une installation minimale de 4 m2. Un appel aux projets sera également lancé sous peu à l'adresse des collectivités. Un audit énergétique sera proposé gratuitement à vingt d'entre elles, tandis que des primes substantielles à l'installation viendront en sus.

Le lieu de la signature de cet accord, le domaine provincial de Chevetogne, était par ailleurs symbolique. Avec 2.400 m2 de panneaux destinés au chauffage de la piscine olympique, il s'agit du plus grand producteur d'énergie solaire en Belgique. Une installation dont la création a été décidée dès le début des années 1970, ce qui était carrément révolutionnaire pour l'époque. Des panneaux installés dès 1979, dont les ingénieurs belges et étrangers suivent l'évolution avec attention. A part une maintenance spécifique des canalisations et de l'isolation, les panneaux eux-mêmes semblent parfaitement résister aux assauts du temps. Ils sont la preuve de la longévité de ce type de matériel et donc de sa capacité d'amortissement.