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Solar energy

Solar energy refers to the energy derived in form heat and light from solar radiations. This is one of the best renewable energy source provided by nature. It is available abundantly (3.8 million exaJoules).  Solar energy is one of the best forms of alternative energy available to mankind and serves as mitigation for addressing concerns on climate changes, greenhouse emissions and pollution.

Solar technology develops methods by which solar energy can be harnessed into usable forms like power, heat and thermal applications. The applications of solar technology are solar water heaters, traffic lights, solar cookers, power plants catering to smaller community, solar cars to name a few.

Solar technologies will boom in the upcoming years due to the environment green initiatives. In the modern world, solar lighting is preferred way of illuminating large buildings like office spaces, airports and shopping malls. This reduces cost of power and makes the environment sustainable.

Applications with solar technologies will be the future as there will be significant thrust in investments from both the government and corporate sectors. Prices may come down due to new entrants and interest in alternative energy production. One can expect significant breakthrough in research and inventions of solar applications as many countries are already investing on this form of energy.

MNRE to introduce quality check system for solar products

The key question of course is whether MNRE has the required expertise within itself for preparing such benchmarking procedures. While it might seem simple enough, panels and inverters could get rather complex if one starts getting into the micro details. Which is why I will be interested to know if India has expertise enough to prepare such quality benchmarks. Not that it is too much of a problem if we don’t – the Germans are always there to help us, and if one were to go by the number of German companies present at Intersolar, access to these experts should hardly be an issue!

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MNRE to introduce quality check system for solar products

If diesel is a necessary evil, make the most out of it – through CHP

Through what in industry parlance is known as CHP, or combined heat and power. Essentially, what you do is that you capture the exhaust heat that comes out of a diesel genset and utilize this heat either for industrial heating or drying purposes, or, through a vapour absorption machine (VAM), convert this heat to cold for air-conditioning or cold storage or whatever.

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If diesel is a necessary evil, make the most out of it – through CHP

Intersolar – And the Bandwagon Chugs On?

One would have thought the solar fatigue would have set in. Heck, who would like another solar show in which the usual suspects (in order words, people like me), spoke the same faded and jaded words!Somehow, the just-concluding Intersolar edition 2011 at Mumbai appears to have done a decent job. The conferences were reasonably well attended, and the parallel exhibition had over 250 exhibitors.

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Intersolar – And the Bandwagon Chugs On?

Discovery of a ‘dark state’ could mean a brighter future for solar energy

The maximum theoretical efficiency of the silicon solar cell in use today is approximately 31 percent, because much of the sun’s energy hitting the cell is too high to be turned into usable electricity. That energy, in the form of “hot electrons,” is instead lost as heat. Capturing hot electrons could potentially increase the efficiency of solar-to-electric power conversion to as high as 66 percent.

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Discovery of a ‘dark state’ could mean a brighter future for solar energy

New record voltage for organic solar cells opens the tech to consumer electronics

Molecular Solar Ltd, a spinout company from the University of Warwick, has achieved a significant breakthrough in the performance of solar photovoltaic (PV) cells. They have achieved and demonstrated a record voltage for organic photovoltaic cells that means these highly flexible, low cost solar cells can now be devolved for commercial uses in a wide range of consumer electronics.
The Company’s most recent advance in the development of its organic photovoltaic (OPV) cell technology is the realisation of cells with open-circuit voltages in excess of 4 volts for the first time. Molecular Solar’s research team believe this is a record for an OPV device. Dr Ross Hatton, Research Director of the company commented:
“This is an important advance. We are now very close to having highly flexible organic photovoltaic cells that will be capable of delivering electrical energy at a voltage suitable for recharging lithium ion batteries that are widely used in portable consumer electronics. Remarkably, this high voltage is achieved using a cell with only 4 junctions (sub-cells)”.
University of Warwick researcher Professor Tim Jones, who is Chief Technology Officer of Molecular Solar, added: “The first generation of organic photovoltaics will be exceptionally well matched to consumer electronics applications. The advantage of Molecular Solar’s high voltage cells is that a single cell can be used with no requirement to connect multiple cells in series for these applications, saving manufacturing cost.”
Andrew Oldfield, Head of Cleantech at Mercia Fund Management said, “We were attracted to Molecular Solar’s unique approach to realizing truly flexible, environmentally sustainable photovoltaics that are well matched to the burgeoning portable consumer electronics market.”
Molecular Solar are currently finalising a £5m investment round to complete the up-scaling of their OPV and MS-Flexifilm™ electrode technology.

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New record voltage for organic solar cells opens the tech to consumer electronics

Mobile electrons multiplied in quantum dot films

Researchers of the Opto-electronic Materials section of the TU Delft and Toyota Europe have demonstrated that several mobile electrons can be produced by the absorption of a single light particle in films of coupled quantum dots. These multiple electrons can be harvested in solar cells with increased efficiency.
The researchers published their findings in the October issue of the scientific journal Nano Letters.
A way to increase the efficiency of cheap solar cells is the use of semiconductor nanoparticles, also called quantum dots. In theory, the efficiency of these cells can be increased to 44%. This is due to an interesting effect that efficiently happens in these nanoparticles: carrier multiplication. In the current solar cells, an absorbed light particle can only excite one electron, while in a quantum dot solar cell a light particle can excite several electrons. Multiplying the number of electrons results in the enhancement of current in solar cells, increasing the overall power conversion efficiency.
Carrier Multiplication
Several years ago it was demonstrated that carrier multiplication is more efficient in quantum dots than in traditional semiconductors. As a result, these quantum dots are currently heavily investigated worldwide for use in solar cells. A problem with using carrier multiplication is that the produced charges live only a very short time (around 0.00000000005 s) before they collide with each other and disappear via a decay process known as Auger recombination. The main current challenge is to proof that it is still possible to do something useful with them.
Mobile charges
The researchers from Delft have now demonstrated that even this very short time is long enough to separate the multiple electrons from each other. They prepared films of quantum dots in which the electrons can move so efficiently between the quantum dots that they become free and mobile before the time it takes to disappear via Auger recombination. In these films up to 3.5 free electrons are created per absorbed light particle. In this way, these electrons do not only survive, they are able to move freely through the material to be available for collection in a solar cell.

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Mobile electrons multiplied in quantum dot films

Redox flow batteries, a promising technology for renewable energies integration

Today there is a wide variety of energy storage technologies at very different stages of development. Among them, the Redox Flow Battery (RFB) is an innovative solution based on the use of liquid electrolytes stored in tanks and pumped through a reactor to produce energy. Tecnalia is currently working in the development of high performance RFBs.
RFB is, by its very nature, a modular and highly flexible technology with very rapid response, little environmental impact and considerable potential for cutting costs. This is the reason why Redox Flow Batteries are emerging as a very promising option for stationary storage in general and for renewable applications in particular.
Renewable energies
There is no doubt that the development of renewable energies will be a key milestone in the way towards a new environmentally-friendly energy model., However, their variability and limited predictability are posing a problem for the operation of the system and, as a result, a barrier to their massive penetration.
A clear example of these difficulties is the need to maintain backup systems that generate energy during low wind or low solar irradiance periods. On the other side, high renewable generation can lead to energy waste during low demand periods.
Redox Flow Batteries are considered as a highly adequate technology to mitigate the variability of renewable energies and to improve their dispatchability, that is, to provide the capability to regulate the output in a similar way to conventional power stations. The energy stored during periods of high renewable production can be used to compensate for the lack of generation when the weather conditions are less favourable.

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Redox flow batteries, a promising technology for renewable energies integration

Solar inverters: Losses are cut in half

A switching trick makes it possible to cut the losses of a series-production inverter in half and increase the efficiency from 96 to 98 percent. The HERIC®-topology makes it possible to achieve a world-record efficiency of more than 99 percent.
“It was a matter of minutes,” Dr. Heribert Schmidt remembers the day in spring of 2002. To find opportunities for improvement, he had often pondered about the switching plan of an inverter while in his office at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany. A sudden flash of inspiration — and a solution that was ingeniously simple came to his mind. He immediately went to get an inverter from the laboratory, laid a few new strips and installed two additional semiconductor switches. “Then it required only a little bit of work on the controls — and we already had the proof!” This is how the electrical engineer, who holds a doctorate in electrical engineering, described the revolutionary step in brief: the losses could be halved and the degree of effectiveness could be increased from 96 to 98 percent.
Key component for electricity feed
After the solar generator, the inverter is the second key component of a grid-linked photovoltaics system. Solar modules generate direct current. If the current is to be fed into the public grid, then it must be converted into grid-compatible alternating current. The inverter handles this task. Single-phase feed inverters consist of three essential parts: the buffer capacitor at the input which provides intermediate storage for the direct current from the solar generator; the inverter bridge with four semiconductor switches that “chop up” the direct current by rapidly switching on and off and as a third component, the inductor at the output that converts the alternating current into a perfect sinus current.
In a short time from the idea to the product
Heribert Schmidt knew: A large portion of the losses are caused by the return of current between the output inductor and the input capacitor. The question therefore was how to prevent this. “That’s easy,” said Heribert Schmidt after a sudden inspiration: “If I decouple the capacitor and the inductors completely from each other at certain intervals, then it is impossible for a return current to flow, and electro-magnetic disturbances cannot occur at the input as a result of voltage spikes.” He immediately had his invention patented as HERIC® topology and began to develop a new series of devices with the SUNWAYS company in Konstanz, Germany. Experts were astonished, and awards and recognition followed quickly: “By far the best device in this performance category.” In the meantime, an encompassing patent has been awarded to the basic idea and the Fraunhofer-Gesellschaft is in negotiations with additional licensees.

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Solar inverters: Losses are cut in half

Flexible films for photovoltaics

Dr. Sabine Amberg-Schwab and Dr. Klaus Noller have developed a specially coated polymer film that is ideally suited for encapsulating inorganic solar cells. Photovoltaics, displays that can be rolled up and flexible solar cells. Barrier layers,that protect thin-film solar cells from oxygen and water vapor and thus increase their useful life are an essential component. Potato chips and thin-film solar cells are common, that protect them from air and water vapor: the chips in order to stay fresh and crisp; the solar cells in order to have a useful life that is as long as possible. In some cases,glass is used to protect the active layers of the solar cells from environmental influences.

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Flexible films for photovoltaics