Philae may not have energy to send results to Earth, says ESA

Europe's robot lab Philae may not have enough power to send to Earth the results of today's drill into the surface of its host comet, mission scientists have said.

"We are not sure there is enough energy so that we can transmit" the data, lander manager Stephan Ulamec said at a press conference webcast from European Space Agency (ESA) ground control in Germany.
Scientists are to decide whether to try a risky drilling procedure to enable an exploration probe to examine samples from the surface of a comet before its batteries run out.

The probe on Wednesday floated away from its planned landing site after harpoons designed to hold it down on the comet failed to deploy.
It is now resting precariously on two out of three legs in the shadow of a cliff on the comet.

• The lack of light means the probe, dubbed Philae, would not draw sufficient energy to operate on its solar panels as hoped once its batteries run out.

• The ESA team are also uncertain of its exact position, making it difficult to "hop" the probe into a better position using its landing gear.

The probe was supposed to drill into the surface of the celestial body after landing, but its unstable position and the comet's weak gravitational pull means there is a risk it could bounce off if the drill is deployed.
Despite the landing setbacks, the mission has achieved many breakthroughs, including the first time a spacecraft has followed a comet rather than just whizzing past and the first time a probe has landed on a comet.
Comets are of interest to scientists because they are remnants from the formation of our solar system, over 4.6 billion years ago.
These masses of ice and rock have preserved ancient organic molecules like a time capsule and may provide insight into how planets and life evolved.
Even if Philae is unable to drill into the surface to analyse samples, the Rosetta spacecraft will follow the comet until at least the end of 2015, even as it passes closest to the sun on its orbit.
[http://www.rte.ie]
14/11/1
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Related:

• Scientists working on Philae comet lander say it is time to take more risks with the probe, amid fears its battery might die in hours....

• Rosetta-Mission: "Philae" hat schon fast keinen Strom mehr ...

Related:

• The Rosetta comet landing has made history (Space probe, Philae, reaches comet’s surface first time in history)

• Σήμερα η ιστορική απόπειρα προσεδάφισης ρομπότ σε κομήτη ...

• Europe's mission to land the first-ever probe on a comet was on track Wednesday with one final "go" pending for the robot lab to eject from its mothership and start a nail-biting seven-hour descent...

• Διαστημική αποστολή «Ροζέτα»... εξετελέσθη

• Rosetta space probe makes historic rendezvous with comet

• Rosetta spacecraft to be woken after nearly three years, ESA awaits signs of life(20/1/13)

• Rosetta: Raumsonde erfolgreich aus dem Tiefschlaf erwacht ....

• Après 31 mois de sommeil, la sonde spatiale Rosetta se réveille...

The Rosetta comet landing has made history (Space probe, Philae, reaches comet’s surface first time in history)

After 10 years of hard work and one nerve-wracking night, the Rosetta mission has made history by landing on the surface of a comet.

The lander Philae was confirmed to touch down on the surface of the comet more than 300 million miles away at 11:05 a.m. Eastern. Now, scientists expect it to send a panoramic image home and begin analyzing the comet for scientists back on Earth.

Philae is already transmitting scientific data back home, but we're still waiting to see whether the probe is in a stable position. Until we know it's anchored tight, it could roll onto its back and never get back up.

Tensions were high in the European Space Agency's German mission control center, especially as the landing window approached. Because the comet that Philae landed on is so far from Earth, there's a communications delay of 28 minutes. So as the minutes ticked by, the Rosetta team knew that Philae had already either landed or failed — and there was nothing they could do but wait for the data to reach them. Those following the video online were nearly as desperate for news, and Twitter became a sounding chamber of anticipation and excitement.

But a few minutes after 11 a.m., the stern, cautious expressions of the mission control team melted into smiles. And just like that, the world swiveled from anxiety to elation: Philae was on the surface of the comet and ready to do some science.
 [washingtonpost.com]
12/11/14
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• Σήμερα η ιστορική απόπειρα προσεδάφισης ρομπότ σε κομήτη ...

• Europe's mission to land the first-ever probe on a comet was on track Wednesday with one final "go" pending for the robot lab to eject from its mothership and start a nail-biting seven-hour descent...

• Διαστημική αποστολή «Ροζέτα»... εξετελέσθη

• Rosetta space probe makes historic rendezvous with comet

• Rosetta spacecraft to be woken after nearly three years, ESA awaits signs of life(20/1/13)

• Rosetta: Raumsonde erfolgreich aus dem Tiefschlaf erwacht ....

• Après 31 mois de sommeil, la sonde spatiale Rosetta se réveille...

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For the first time in the history of space exploration a research probe has reached the surface of a comet.
The robotic lander Philae of the European Space Agency separated from the spacecraft Rosetta and landed on the comet 67P/Churyumov-Gerasimenko 500 million kilometers away from the Earth.
Philae separated from the Rosetta spacecraft at 11:35 Moscow time.

 The journey from Rosetta to the comet’s surface lasted about seven hours.

Rosetta and Comet 67P/Churyumov-Gerasimenko, which was discovered in 1969 by Soviet astronomers Klim Churyumov and Svetlana Gerasimenko, now lie about half way between the orbits of Jupiter and Mars, rushing towards the inner Solar System at nearly 55,000 kilometers per hour, the ESA said.
Rosetta will follow the comet for more than a year to provide a detailed scientific study of the Solar System body.
[en.itar-tass.com]
12/11/14

India makes history with first spaceship to orbit Mars

India triumphed in its first interplanetary mission, placing a satellite into orbit around Mars on Wednesday morning and catapulting the country into an elite club of deep-space explorers.
Scientists broke into wild cheers as the orbiter's engines completed 24 minutes of burn time and maneuvered into its designated place around the red planet.
The success of India's Mars Orbiter Mission, affectionately nicknamed MOM, brings India into an elite club of Martian explorers that includes United States, the European Space Agency and the former Soviet Union.

"Today Mars has met MOM. MOM never disappoints. History has been created today," Prime Minister Narendra Modi announced amid applause at the Indian Space Research Organisation command center in Bangalore."We have gone beyond the boundaries of human enterprise and innovation."
"We have navigated our craft through a route known to very few," Modi said, congratulating both the scientists and "all my fellow Indians on this historic occasion."
The Indian Space and Research Organisation described the mission as flawless.
The success marks a milestone for the space program in demonstrating that it can conduct complex missions and act as a global launch pad for commercial, navigational and research satellites.
It's also a major feat for the developing country of 1.2 billion people, most of whom are poor. At the same time, India has a robust scientific and technical educational system that has produced millions of software programmers, engineers and doctors, catapulting many into the middle class.
More than half the world's previous attempts — 23 out of 41 missions — have failed, including one by Japan in 1999. The United States had its first success with a 1964 flyby by a spacecraft called Mariner 4, returning 21 images of the surface of the planet. The former Soviet Union reached the planet in 1971, and the European Space Agency in 2003.
India was particularly proud that MOM, a 1,350-kilogram (nearly 3,000-pound) satellite, was developed with homegrown technology and for a bargain price of about $75 million. NASA's much larger Mars Atmosphere and Volatile Evolution mission, or Maven, which reached its position around the red planet on Sunday, cost nearly 10 times as much at $671 million.

• MOM will now circle the planet for at least six months on an elliptical path that gets within 365 kilometers (227 miles) of the planet's surface at its closest and 80,000 kilometers (49,700 miles) at its farthest.

Five solar-powered instruments will gather data that will help determine how Martian weather systems work and what happened to the water that is believed to have once existed on Mars in large quantities. It also will search Mars for methane, a key chemical in life processes on Earth that could also come from geological processes.
None of the instruments will send back enough data to answer these questions definitively, but experts say the data will help them better understand how planets form, what conditions might make life possible and where else in the universe it might exist.

• There are three more satellites already circling the planet — NASA's Mars Reconnaissance Orbiter and Mars Odyssey, and the ESA's Mars Express. On the Martian surface, NASA's Curiosity and Opportunity rovers are rolling across rocky terrain. 

India has said the spacecraft — also called Mangalyaan, meaning "Mars craft" in Hindi — is chiefly meant to showcase the country's ability to design, plan, manage and operate a deep-space mission. India has already conducted dozens of successful satellite launches, including sending up the Chandrayaan-1 lunar orbiter, which discovered key evidence of water on the Moon in 2008. 
AP
 haaretz.com
24/9/14
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Related:

• India launches its first-ever probe towards Mars (video)

• Indian Mars mission suffers glitch but 'no setback' ... 

• India’s First Mars Probe Successfully Leaves Earth's Orbit....

Rosetta space probe makes historic rendezvous with comet

European scientists announced the historic rendezvous on Wednesday between a comet and the Rosetta spacecraft after a 10-year, six billion-kilometre (3.7-billion-mile) chase through the solar system.

The scout Rosetta has now become the first envoy to orbit one of these wanderers of the solar system in deep space, the European Space Agency (ESA) said.

Scientists and spectators at ESA’s mission control in Darmstadt, Germany, cheered after the spacecraft successfully completed its final thrust to swing alongside comet 67P/Churyumov-Gerasimenko.

ESA chief Jean-Jacques Dordain says the probe’s rendezvous with 67P is an important milestone in Rosetta’s life.

The goal of the mission is to orbit 67P from a distance of about 100 kilometres (60 miles) and observe the giant ball of dust and ice as it hurtles toward the sun. If all goes according to plan, Rosetta will drop the first ever lander, a robot chemistry lab, onto a comet in November.

Scientists hope this will help them learn more about the origins of comets, stars and planets.

Orbital entry was triggered by a small firing of her thrusters, lasting just six minutes and 26 seconds, starting at 0900 GMT on Wednesday, it said.

“This burn will tip Rosetta into the first leg of a series of three-legged triangular paths about the comet,” it said.

Top officials from ESA will be were at mission control in Darmstadt, Germany, waiting for the signals to start and stop this crucial final operation to be safely received by ground monitoring stations, 22 minutes later.

The “pyramidal” orbits will put the craft at a height of about 100 kilometres (60 miles) above the comet, said Sylvain Lodiot, Rosetta’s flight operations manager. Each leg of the triangle will be around 100 kilometres and take Rosetta between three and four days to complete.

The arrival will mark a key moment of the boldest project ever undertaken by ESA—a 1.3-billion-euro ($1.76-billion) investigation into one of the enigmas of the solar system.

Comets are believed by astrophysicists to be ancient ice and dust left from the building of the solar system around 4.6 billion years ago. This cosmic rubble is the oldest, least touched material in our stellar neighbourhood.

Understanding its chemical ID identity and physical composition will give insights into how the planets coalesced after the sun flared into light, it is hoped.

t could also determine the fate of a theory called “pan-spermia,” which suggests comets, by smashing into the infant Earth, sowed our home with water and precious organic molecules, providing us with a kickstart for life.

Navigational feat

Rosetta was poised to meet up with Comet “C-G” more than 400 million kilometres from where it was launched.

Getting there has been an unprecedented navigational exploit. Launched in March 2004, the three-tonne craft has had to make four flybys of Mars and Earth, using their gravitational force as a slingshot to build up speed.

It then entered a 31-month hibernation as light from the distant Sun became too weak for its solar panels. That period ended in January with a wake-up call sent from Earth.

The spacecraft is named after the famous stone, now in the British Museum, that explained Egyptian hieroglyphics, while its payload Philae is named after an obelisk that in turn helped decipher the Rosetta stone.

The four-kilometre comet is named after two Ukrainian astronomers who first spotted it in 1969.

(FRANCE24 with AP and AFP)
http://www.france24.com/en/20140806-rosetta-space-probe-comet-meeting-solar-system/
6/8/14
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Related:

• Rosetta spacecraft to be woken after nearly three years, ESA awaits signs of life(20/1/13)

• Rosetta: Raumsonde erfolgreich aus dem Tiefschlaf erwacht ....

• Après 31 mois de sommeil, la sonde spatiale Rosetta se réveille...

World’s largest solar boat docks in Paris. -Ending its transatlantic voyage. (2 videos)

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Paris is not new to extreme machines. The world throngs to the French capital every year to be wowed by the cutting-edge technology in either automobiles, at the Paris Motor Show, or aircrafts, at the Paris Air Show. This week, the world’s largest solar-powered boat eased into the Seine, ending its transatlantic voyage.
Docked at the quay in front of Paris’ western Parc André Citroën, the Turanor PlanetSolar catamaran, whose body is made of carbon fibre, exemplifies state-of-the-art solar-powered engineering.



The boat has already racked up some impressive credentials after circumnavigating the globe and breaking the record for a transatlantic journey by a solar-powered vessel. But this time, it also served as an experimental station that enabled scientists from the University of Geneva to conduct atmospheric and oceanic studies in the Gulf Stream in the Atlantic Ocean.
“It was a pleasure conducting experiments on this unique vessel. The advantage of this boat is that because of zero emissions, we were able to conduct studies on aerosols without any hindrance,” said Anh-Dao Le, one of the scientists onboard.

The zero emission is the result of the 29,124 photovoltaic cells that power this 35 metres long, 23 metres wide and 6.30 meters high catamaran. The solar cells, which span 512 square metres of the deck area, charge 8.5 tons of lithium-ion batteries which in turn power the two propellers. The boat, which can accommodate nine people (5 crew members and 4 scientists), has a maximum speed of 14 knots, with an average speed of 5 knots.

According to Planetsolar’s head of communications, Rachel Bros de Puechredon, who was part of the crew on this transatlantic voyage, the boat has demonstrated not only the long-term feasibility of solar energy on ocean journeys but the vessel’s capabilities as a scientific tool.
“Besides the solar power demonstration, we wanted a second life for it, the kind of which was manifested in this scientific expedition,” she said.

The boat’s unique capabilities were not only in its design, construction and use of alternative energy, but also in its navigation.
“Unlike conventional vessels, the top priority while navigating this boat is the optimisation of energy depending on the sun, wind and water currents,” Bros de Puechredon said.
Although entirely powered by solar energy, the boat does carry an emergency generator in case of extreme weather.
“We had to use the generator in order to escape Hurricane Andrea in June,” Bros de Puechredon recalled.
The Turanor PlanetSolare will be docked at the Parc Andre Citroen until September 15.
 http://www.france24.com/en/20130913-france-world-largest-solar-boat-finishes-transatlantic-voyage-paris
13/9/13

China, EU reach deal on solar panel dispute

BRUSSELS, July 27 (Xinhua) -- The China Chamber of Commerce for Import and Export of Machinery and Electronic Products and the European Commission have reached a deal to resolve a dispute involving solar panels.
"After weeks of intensive talks, I can announce today that I am satisfied with the offer of a price undertaking submitted by China's solar panel exporters," EU Trade Commissioner Karel De Gucht said in a statement, referring to an agreement for a minimum price for China's imports.
"We found an amicable solution ... that will lead to a new market equilibrium at sustainable prices," De Gucht said.

The Commissioner said the next step for him is to table this offer for approval by the European Commission.
Further details of the legal acts concerning the undertaking arrangement can only be released following their adoption by the Commission.
The Chinese Ministry of Commerce, meanwhile, said China welcomes the deal which "showcased pragmatic and flexible attitudes from both sides and the wisdom to resolve the issue."
According to the Ministry of Commerce spokesman Shen Danyang, resolving the trade dispute is conducive to an open, cooperative, stable and sustainable economic and trade relationship between China and the EU.
He added that China is willing to further promote exchanges and cooperation with the EU side in the photovoltaic industry field.
Chinese solar panel production quadrupled between 2009 and 2011 to more than the entire global demand, and the Commission accused China of dumping its solar panels at below the cost of production in Europe.
The European Commission on June 4 decided to impose provisional anti-dumping duties on imports of solar panels, cells and wafers from China.
Starting from June 6, EU imports of Chinese solar products was subject to a punitive duty of 11.8 percent until August 6, from when on, the duty would have been raised to 47.6 percent if the two sides could not sort out the dispute through negotiations.
http://english.cntv.cn
27/7/13
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Related:

• ΕΕ-Κίνα: Πόλεμος για κρασί και φωτοβολταϊκά....Δασμοί και αντι-ντάμπινγκ 

• Χορηγός του Ολυμπιακού η κινεζική εταιρία φωτοβολταϊκών πάνελ, YINGLI SOLAR. Για την αγωνιστική περίοδο 2013 – 2014

• Οι δασμοί στα κινεζικά πάνελ θα πλήξουν την ελληνική αγορά φωτοβολταϊκών;

• Ανησυχία Βερολίνου για «εμπορικό πόλεμο» ΕΕ - Κίνας

Spain’s solar industry to collapse as govt introduces draconian profit caps

One of the main producers of renewable energy in Europe, Spain’s solar industry, is edging toward bankruptcy. Producers say they’ll be unable to repay credits after the government’s decision to cut subsidies. Banks will suffer and jobs will be lost.
Energy Minister José Manuel Soria has introduced a new compensation plan for calculating levels of "reasonable profitability" for renewable-energy production, distribution and transportation. It will reduce payments to companies serving the nation's electrical system by up to 2.7 billion euro annually. It’s hoped the move could help cope with the electricity system deficit that has been growing since 2005 and now exceeds 25 billion euro.

To sap the annual deficit, which has been estimated by the government at 4.5 billion euro this year, Spain is set to raise consumers' electric bills by about 3.2 percent starting from August, contributing about 400 million euro in extra revenue for the system this year and 900 million euro next year, the Wall Street Journal reports.


Experts are warning that with the increased levies on self-consumed solar energy so high many households will have to pay more for the electricity they generate themselves than they would for regular grid power. 
The main trade association for Spain's electric utilities which distribute most the country's electricity said "the cuts will compel our member companies to undertake a drastic reduction in jobs and review their investments in Spain," Asociación Española de la Industria Eléctrica (Unesa) warned.

Spain has over 4GW of installed capacity. For several years the government reportedly pushed electricity retailers to pay above-market, unaffordable prices to renewable-power producers.

This handout picture released by Gemasolar shows the Torresol Energy Gemasolar thermasolar plant in Fuentes de Andalucia near Sevilla, southern Spain. (AFP Photo/Gemasolar)

Big subsidies triggered a boom in solar-power installations that, according to the Wall Street Journal, far exceeded official government targets. Between 2006 and 2012, when renewable-energy output doubled, Spain boasted the fourth-largest such industry in the world, according to the Economist.

In 2012 clean energy subsidies in Spain hit 8.6 billion euro, nearly 1 percent of GDP. To fund the expansion, Spanish banks lent the solar-energy companies nearly 30 billion euro. Potential loan defaults could worsen the already heavy burden on Spanish banks. The government is said to be in talks with banks to forestall bankruptcies, with five of the biggest utilities saying the new reforms will jointly cost them 1 billion euro a year.

With the new plan brought into action, the government has capped profits for the solar energy sector at 7.5 percent before tax to 5.5 percent after tax. Spanish trade associations have been shocked by the decision saying the new rate is less than the rate that industry insiders are able to borrow at, leading many to “bankruptcy because they won't be able to repay the credit that financed them.”

According to the energy minister, "this reform is not wedded to any part of the electric sector."

"We did what we had to do," Soria said. 
http://rt.com/business
23/7/13

L'Allemagne arrêtera ses subventions à l'énergie solaire d'ici à 2018

L'Allemagne devrait arrêter de subventionner l'énergie solaire d'ici à 2018 au plus tard, a affirmé lundi 8 juillet le ministre de l'environnement, Peter Altmaier, qui avait commencé dès l'an dernier à baisser la voilure du soutien très généreux accordé au photovoltaïque.

Peter Altmaier, conservateur, avait fixé l'an dernier un plafond de capacité solaire installée au-delà duquel les pouvoirs publics arrêteraient de subventionner cette énergie. Il a déclaré que ce seuil de 52 gigawatts serait vraisemblablement atteint en 2017, au plus tard en 2018.


A l'heure actuelle, les panneaux solaires installés en Allemagne ont une capacité cumulée de 34 gigawatts. Le régime de subventions – sous forme d'un prix garanti payé aux producteurs solaires pour chaque kilowattheure produit – a conduit à un véritable boom ces dernières années, particuliers et agriculteurs notamment se découvrant des vocations de producteur photovoltaïque. Le prix très bas des panneaux solaires en provenance d'Asie a aussi contribué à cet engouement.

PROBLÈMES DE STABILITÉ DU RÉSEAU

Le développement à marche forcée du solaire s'inscrit dans le cadre de la transition énergétique allemande, qui doit voir la part des renouvelables dans la production électrique passer à 80 % d'ici à 2050. Mais il pose aussi des problèmes de stabilité du réseau, la production photovoltaïque étant aléatoire et difficile à prédire.

La chancelière Angela Merkel, en campagne pour un troisième mandat, a promis une remise à plat des subventions aux renouvelables après les élections législatives de septembre, sur fond de critiques notamment de la part de l'industrie.

L'Allemagne "a investi jusqu'à maintenant 216 milliards d'euros dans les renouvelables", commentait ainsi dans un entretien publié par le Handelsblat lundi le patron du conglomérat industriel Siemens, et "le plus gros morceau est allé au photovoltaïque, la technologie qui contribue le moins à un approvisionnement sûr".

En soutenant le secteur solaire, "nous voulions aider nos enfants, mais maintenant ils sont grands", estime Johannes Teyssen, patron d'EON, interviewé lui aussi dans le Handelsblatt de lundi. Le surcoût généré par le subventionnement des renouvelables se répercute sur les prix, et les prix de l'électricité en Allemangne sont parmi les plus élevés d'Europe.
http://www.lemonde.fr
8/7/13

Αυτοκόλλητες ηλιακές κυψέλες για κάθε επιφάνεια

Ερευνητές από το Πανεπιστήμιο του Στάνφορντ ανακοίνωσαν ότι ανέπτυξαν μια αυτοκόλλητη ηλιακή κυψέλη που, σε αντίθεση με τις συμβατικές, μπορεί να τοποθετηθεί σε πολλών τύπων σκληρές επιφάνειες. Η εφεύρεσή τους, υποστηρίζουν, αυξάνει εντυπωσιακά τις δυνατότητες διείσδυσης της τεχνολογίας ηλιακής ενέργειας.
Υπό κανονικές συνθήκες, λεπτές «ταινίες» ηλιακών κυψελών τοποθετούνται σε εύκαμπτα υποστρώματα γυαλιού και πυριτίου, καθώς οι περισσότερες μη συμβατικές επιφάνειες δεν μπορούν να υποβληθούν στις θερμικές και χημικές διεργασίες που χρειάζονται για την παραγωγή των κυψελών.

Όπως εξηγούν οι ερευνητές στην έκθεσή τους, στην επιθεώρηση Nature Scientific Reports, η διαδικασία που επινόησαν ξεπερνά αυτό το εμπόδιο γιατί δεν προϋποθέτει την κατασκευή της ηλιακής κυψέλης πάνω στο τελικό επίστρωμα. Η μέθοδός τους, λένε, θα μπορούσε να οδηγήσει σε φθηνότερες, ελαφρύτερες, πιο εύκαμπτες κυψέλες.
Οι επιστήμονες παρομοιάζουν την κυψέλη τους με ένα... σάντουιτς, αποτελούμενο από μια πολύ λεπτή ταινία νικελίου, μια δεύτερη ταινία πυριτίου και διοξειδίου του πυριτίου και ένα προστατευτικό πολυμερές, τα οποία συνδέονται με μια θερμοευαίσθητη μεμβράνη. Όταν τοποθετηθούν σε νερό σε θερμοκρασία δωματίου, η ηλιακή κυψέλη αφαιρείται, σαν να ξεκολλάει, και μπορεί να τοποθετηθεί σε πάσης φύσεως επιφάνειες.

Ηλιακή κυψέλη τοποθετημένη πάνω σε επαγγελματική κάρτα.

Στόχος του Σιαολίν Ζενγκ και της ομάδας του ήταν να μεταφέρουν τα ενεργά υλικά της ηλιακής κυψέλης - αυτά που συλλέγουν το ηλιακό φως και παράγουν ηλεκτρική ενέργεια- από το σκληρό υπόστρωμα σε μια άλλη επιφάνεια, π.χ. ένα κομμάτι χαρτιού, πλαστικού ή ακόμη και στο πίσω μέρος ενός κινητού τηλεφώνου.
Όπως συμβαίνει με άλλες ηλιακές κυψέλες, καλώδια χρησιμοποιούνται για να μεταφέρουν την ηλεκτρική ενέργεια, όμως οι συγκεκριμένες μπορούν να τοποθετηθούν σε καμπύλες επιφάνειες. Επιπλέον, καθώς είναι ιδιαίτερα ελαφριές, εγκαθίστανται ευκολότερα σε σχέση με τα συμβατικά πάνελ.

Διαδικασία εφαρμογής αυτοκόλλητης ηλιακής κυψέλης. (Πηγή: Chi Hwan Lee, Stanford School of Engineering).

«Είναι σημαντικό το γεγονός ότι [με την τεχνική αυτή] δεν είχαμε καμία απώλεια αποδοτικότητας» σε σχέση με τις συμβατικές κυψέλες, προσθέτει ο Ζενγκ. Επόμενος στόχος της ομάδας του είναι να εφαρμόσει την ίδια τεχνική σε κυψέλες από ακόμη αποδοτικότερα υλικά. 
 .naftemporiki.gr
23/12/12
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• Peel-and-Stick solar panels from Stanford engineering

For all their promise, solar cells have frustrated scientists in one crucial regard – most are rigid. They must be deployed in stiff, often heavy, fixed panels, limiting their applications. So researchers have been trying to get photovoltaics to loosen up. The ideal: flexible, decal-like solar panels that can be peeled off like band-aids and stuck to virtually any surface, from papers to window panes.
Now the ideal is real. Stanford researchers have succeeded in developing the world's first peel-and-stick thin-film solar cells. The breakthrough is described in a paper in the December 20th issue of Scientific Reports.
Unlike standard thin-film solar cells, the peel-and-stick version from Stanford does not require any direct fabrication on the final carrier substrate. This is a far more dramatic development than it may initially seem. All the challenges associated with putting solar cells on unconventional materials are avoided with the new process, vastly expanding the potential applications of solar technology.
Thin-film photovoltaic cells are traditionally fixed on rigid silicon and glass substrates, greatly limiting their uses, says Chi Hwan Lee, lead author of the paper and a PhD candidate in mechanical engineering. And while the development of thin-film solar cells promised to inject some flexibility into the technology, explains Xiaolin Zheng, a Stanford assistant professor of mechanical engineering and senior author of the paper, scientists found that use of alternative substrates was problematic in the extreme.
"Nonconventional or 'universal' substrates are difficult to use for photovoltaics because they typically have irregular surfaces and they don't do well with the thermal and chemical processing necessary to produce today's solar cells," Zheng observes. "We got around these problems by developing this peel-and-stick process, which gives thin-film solar cells flexibility and attachment potential we've never seen before, and also reduces their general cost and weight."
Utilizing the process, Zheng continues, researchers attached their solar cells to paper, plastic and window glass among other materials.
"It's significant that we didn't lose any of the original cell efficiency," Zheng said.

This shows demonstrations of the Stanford peel-and-stick thin-film solar process and various applications.
(Photo Credit: Chi Hwan Lee, Stanford School of Engineering.)

The new process involves a unique silicon, silicon dioxide and metal "sandwich." First, a 300-nanometer film of nickel (Ni) is deposited on a silicon/silicon dioxide (Si/SiO2) wafer. Thin-film solar cells are then deposited on the nickel layer utilizing standard fabrication techniques, and covered with a layer of protective polymer. A thermal release tape is then attached to the top of the thin-film solar cells to augment their transfer off of the production wafer and onto a new substrate.
The solar cell is now ready to peel from the wafer. To remove it, the wafer is submerged in water at room temperature and the edge of the thermal release tape is peeled back slightly, allowing water to seep into and penetrate between the nickel and silicon dioxide interface. The solar cell is thus freed from the hard substrate but still attached to the thermal release tape. Zheng and team then heat the tape and solar cell to 90°C for several seconds, then the cell can be applied to virtually any surface using double-sided tape or other adhesive. Finally, the thermal release tape is removed, leaving just the solar cell attached to the chosen substrate.
Tests have demonstrated that the peel-and-stick process reliably leaves the thin-film solar cells wholly intact and functional, Zheng said. "There's also no waste. The silicon wafer is typically undamaged and clean after removal of the solar cells, and can be reused."
While others have been successful in fabricating thin-film solar cells on flexible substrates before, those efforts have required modifications of existing processes or materials, noted Lee. "The main contribution of our work is we have done so without modifying any existing processes, facilities or materials, making them viable commercially. And we have demonstrated our process on a more diverse array of substrates than ever before," Lee said.
"Now you can put them on helmets, cell phones, convex windows, portable electronic devices, curved roofs, clothing – virtually anything," said Zheng.
Moreover, peel-and-stick technology isn't necessarily restricted to thin-film solar cells, Zheng said. The researchers believe the process can also be applied to thin-film electronics, including printed circuits and ultra thin transistors and LCDs.
"Obviously, a lot of new products – from 'smart' clothing to new aerospace systems – might be possible by combining both thin-film electronics and thin-film solar cells," observed Zheng. "And for that matter, we may be just at the beginning of this technology. The peel-and-stick qualities we're researching probably aren't restricted to Ni/SiO2. It's likely many other material interfaces demonstrate similar qualities, and they may have certain advantages for specific applications. We have a lot left to investigate."

This is a process developed for peel-and-stick thin-film solar cell from Stanford.
(Photo Credit: Chi Hwan Lee, Stanford School of Engineering)

Source: Stanford School of Engineering