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Green Building Ideas:Using Solar panels as roofing sheet instead of asbestos.


Using Solar panels as roofing sheet instead of asbestos. Simple process for creating affordable housing especially for the rural poor along with doing  village electrification.  With this thought in mind I spoke to one of my friends who is a Block Development Officer in the state of Orissa. The reception to my idea was instant. Rural electrification.

What if the Solar OPEX model which I helped devise and is working wonders for  the Indian cities be utilized for the villages? While taking off the load from Malls, Commercial centres and the rest which guzzle energy would free up plenty of energy for the state government to provide it to the rural poor, sadly the infrastructure to carry it is not there. We would require the large pylons to be installed first, then string the heavy duty cables then create sub-stations etc. All this network requires enormous amount of synergy between various stake holders and it is nothing but a nightmare in India.

So if I can convince an investor, who is already supportive of my Solar OPEX   concept and we are already having 2MW worth of commitments, for institutional and commercial establishment each, and work has already begun past the inception stage towards EPC; the same amount or perhaps more in Rural Electrification?

We have thousands of home in Rural India who have none or limited access to electricity. And also thousands of homes who have thatched /asbestos roof, which under various programs are being removed to give FRP or GI-Sheet roofing. Solar Panels by default come in metal trays which can also act in -parts as roof. Where that is not possible a Solar “trees” can be planted within the village at strategic locations and the power distributed within its periphery.

So if my B.D.O friend can devise an instrument where the various subsidies which are given to Kerosene, Diesel and roofing materials can be accumulated under one program and driven by say the MNRE & NREGA  missions combined,  which one can find by clicking on the link  and provide the subsidies to the investor of Solar, this idea of village electrification would become possible in the shortest possible period.

It is a Green Business Idea which corporates must think of coming around too, and frankly there would be no competition as the scale is so vast that even 10 large investors with an appetite of 100MW each can not consume it.

Moreover, as investors are more interested in their RoI, this is the right opportunity for them to invest. The subsidy on Diesel and Kerosene is breaking the back of the Indian economy. So if we can even implement a model of distributed generation for Malls, Cold Store Chains etc mandatory within the various city premise, to balance out the expense incurred for creating the rural electrification infrastructure, the total cost saved by the transmission agencies would be  enormous.

It is also a fact that most grid have massive under-recovery from many zones. It would serve well if States took the decision to limit transmission of power through the Grid to these areas, and implement the roof-top solar instead. Thus the defaulters would not be able to draw-in more power than what is generated in the day-time. And while the Grid would supply power into the night it can be timed such that it can be exploited the least.

 

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Green Business Ideas: Greening the Solar RE raw material supply chain.


 A hyperpure polycrystalline single-crystal silicon by the Czochralski process. . (Photo credit: Wikipedia)

The Human race has gone through many ages. The Stone AgeIron Age … and now the Wind & Solar Age (Crystalline Silicone Age ) has begun. And in every age each action has had a reaction. The reason for worry, to put it simply – the stone age guy had lots of resources and very little impact on Earth by his action, while for the RE -age guy the opposite holds true.

Solar Panels, which is predicted as the next messiah along with its other RE counterparts  needs a closer scrutiny from the perspective of what it is manufactured from. Simply because a wrong policy would kill the initiative before it truly matures from the nascent stage it is today. And nothing would give the detractors of RE more pleasure than seeing the premature death of the promising “One”.

Silicon : The chemical compound silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with the chemical formula SiO2. It has been known for its hardness since antiquity. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms.

Uses: Silicon dioxide is used to produce elemental silicon. The process involves high temperature reduction with elemental carbon in an electric arc furnace.The most prevalent bulk material for solar cells is crystalline silicon (abbreviated as a group as c-Si), also known as “solar grade silicon”. Bulk silicon is separated into multiple categories according to crystallinity and crystal size in the resulting ingot, ribbon, or wafer.

Types:

  1. monocrystalline silicon (c-Si): often made using the Czochralski process. Single-crystal wafer cells tend to be expensive, and because they are cut from cylindrical ingots, do not completely cover a square solar cell module without a substantial waste of refined silicon. Hence most c-Si panels have uncovered gaps at the four corners of the cells.
  2. polycrystalline silicon, or multicrystalline silicon, (poly-Si or mc-Si): made from cast square ingots — large blocks of molten silicon carefully cooled and solidified. Poly-Si cells are less expensive to produce than single crystal silicon cells, but are less efficient. United States Department of Energy data show that there were a higher number of polycrystalline sales than monocrystalline silicon sales.
  3. ribbon silicon is a type of polycrystalline silicon: it is formed by drawing flat thin films from molten silicon and results in a polycrystalline structure. These cells have lower efficiencies than poly-Si, but save on production costs due to a great reduction in silicon waste, as this approach does not require sawing from ingots.

Health: Inhaling finely divided crystalline silica dust in very small quantities (OSHA allows 0.1 mg/m3) over time can lead to silicosis, bronchitis, or cancer, as the dust becomes lodged in the lungs and continuously irritates them, reducing lung capacities. However a study which followed subjects for 15 years found that higher levels of silica in water appeared to decrease the risk of dementia. The study found that with an increase of 10 milligram-per-day of the intake of silica in drinking water, the risk of dementia dropped by 11%.

That ends our brief introduction on the most common form of material being used to make Solar Photovoltaic Panels. Now we will understand what does CIGS stand for.

Copper indium gallium selenide (CuIn1-xGaxSe2 or CIGS) is a direct bandgap semiconductor useful for the manufacture of solar cells. Because the material strongly absorbs sunlight, a much thinner film is required than of other semiconductor materials. The CIGS absorber is deposited on a glass backing, along with electrodes to collect current. CIGS’s absorption coefficient is higher than any other semiconductor used for solar modules. Devices made with CIGS belong to the thin-film category of photovoltaics (PV). The market for thin-film PV grew at a 60% annual rate from 2002 to 2007 and is still growing rapidly. Therefore, a strong incentive exists to develop and improve deposition methods for these films that will allow lower cost and increased throughput.

Now having understood the process, what we must look at are the methods of obtaining these minerals. While we may be extolling the virtues of  Solar Photo Voltaic, we must also keep an eye at the process of extraction, refinement and delivery of the basic raw materials that go into production of these wonderful RE tool. In effect we must map the complete manufacturing process and see to it that every time it is sustainable all the way. The question which then rises is, are we doing it ? Because as in other sectors and industry, the fact that the total supply chain must be green and sustainable is gaining traction and the RE industry, which is supposed to be the messiah should look into that aspect too.

Chemical Processing Equipment at a Poly-Silico...

Chemical Processing Equipment at a Poly-Silicon Plant (Photo credit: Wikipedia)

The raw materials that go into making a solar photo voltaic panel starting with raking & tracking system, cabling, inverter and batteries and ending with the voltaic panels are a huge list. Most of them are mined, some like gallium are  recovered from the by-products of zinc refining, Bauxite and the mineral sphalerite, as well as coal, often contain gallium as an impurity. No gallium is mined; it is obtained as a by-product of mining and processing other metals, notably aluminium, zinc and copper, and is produced in any nation that produces these metals.Therefore to get gallium we need all these mines and the problems associated with these will have a direct bearing on Solar PV.

Silica sand is the major raw material used by foundries for making moulds to pour molten metal to cast the intricate metal components for use in practically all industrial sectors. This too is the basic raw material for the most popular and efficient Mono & Poly crystalline Solar PV.

India is mineral-rich. Approximately 24 types of minerals, including iron, bauxite, copper, chromite, gold, lead, manganese, zinc and coal, are found in nearly 50 percent of its total landmass of 3.20 million sq km.  But the main concentrations of this mineral wealth happens to fall in the ecologically rich, tribal-inhabited areas of south, central and north-eastern India that has suffered neglect say environmentalists and development activists. Then there are various emerging issues with mining that can be associated with cultural or industrial factors or trends, such as changes in commodity demand, workforce, or technology. Health and safety is also becoming a major issue in all countries.

It is therefore important that the sunrise industry look into sourcing most of its material from recycled materials. If it starts early, nearly 50% of its raw materials can be sourced from recycled material and this would in effect reduce the over all cost. In time as the industry matures, the older generation panels would itself feed into the raw-material chain.

To achieve this, industry captains need to pause and think in the direction of sustainable supply chain and the Climatologist could surely help with a nudge.

 

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Solar Laptop & Mobile : In your store by next summer?


Last weekend I was invited by BITS Goa Campus ( Birla Institute of Technology ) to give a talk on innovative business strategy in Clean Tech. It was organized by the students with their campus fest aptly named – Quark. G-Con as the green conference to which I was called is being held for the first time by the students. That this event was  to be taken seriously impacted me almost immediately upon being introduced to my co-panelists. Personalties, each with a body of work so profound, Ms Rishu Nigam -TERI, moderator Ms. Juhi Chaudhry of  CNN-IBN, reporter on everything related to environment;  and then the stars  Mr.Ravi Kuchimanchi ; Dr. Ritesh Arya; D.T. Barki; Mr. Atul Gurtu; people who have placed India on the world map with their thoughts and deeds.

Sitting among them, I was inspired and awed. And what inspired me more were the young and brilliant students of BITS, the future of India. This inspiration led me to ask both the students and the eminent personalities to devise a  model to propagate  the clean tech ideas which came into my mind, while listening to fellow panelists.

Self powered Lap-top. An inventor like Mr. Barki could devise surely a solar jacket for the Lap-tops which all the students carry. Imagine if a continuous power could be fed into a lap-top, unplugged and at 90%  battery, via Photo voltaic cells pasted on to the surface therefore unfettered, sensitive as a Casio calculators power panel, so even the ambient light within a room is sufficient? Even if it would be generating power say just 30% in total, it would still increase the battery driven operation time and at the same time reduce the need to plug it to a grid source. Scale it to a Billion laptops in use every hour which can produce 30% power, it is a respectable number in terms of GHG reduction. And when it comes to R&D surely another fellow panelist Mr. Raghvan, GM of Mahindra Solar;  a branch of the blue chip Green Company Mahindra; with international presence and owner of Satyam would like to do a dekho ( hindi; for -look ).

The same could be the fate of the future cell phones, why need a separate charger if one could integrate a semi-circular disk which winds a spring, which in turn applies pressure and excites a quartz ( http://en.wikipedia.org/wiki/Piezoelectricity ) and thus produces a small amount of charge, every time one moves? Remember the old Swiss  wrist watches – the automatic ones ? One never needed to wind it up. This was before cells were born into this world – small made of steel and having a cadmium heart; to be discarded without thought while the Earth is torn open to find more iron ore and methods sought to stop rivers to be poisoned by cadmium.  Coming back to a greener thought – could this be incorporated within the “hostler” that holds the mobile phone? Adding that small amount of charge that keeps the battery from going dead just when you need it most. Perhaps can be even a life-saver; all that a lost trekker needs to do is keep shaking it while making the S.O.S call. Will it save the Earth, count the number of chargers charging the phones around you, as you are reading this and multiply that with infinity – you can bet it would !  And yes perhaps the makers of the next Green Laptop / Cell phone could integrate this piezoelectric  right into the keyboards .  Is  Samsung /Sony / HP / Dell listening ?

Megalopolis like Mumbai has the perpetual problem of sewerage and power. Dr. Ritesh Arya could solve both with his path breaking solution to use the slush to produce steam and run a turbine. And this can be done anywhere as Lava is just under your feet!  Mumbai has its own at Ganeshpuri, then there is  Surajkund and many others, powering India could become limitless. And as the energy needs come form an infinite limitless source called – magma, the World is invited to dip there steel straws into the Earth core and drink aplenty. GHG can be contained. And very much before 2020. Will UNFCCC  at the Rio+20 advocate this for the GCF ?

Simple ideas are most profound and that came from Ravi Kuchimanchi in form of a hay box ( click on this link to see it ). Now, that  led me to think. This can lead to reduction of LGP gas use in the cities. How ? Simple. Ask  the  insulated hot box manufacturers  to design the same and market it. India today loses millions due to subsidy on domestic LPG and other fuel. If even 5% of the overall LPG use can be reduced, the figure would be large. (An amount which can perhaps be pumped back on rural development.) And it is always seen that once you give an innovation which is popular, the people innovate uses which could not have been thought by the inventor.

And speaking of India, a country of – jugaard ( loosely translated – rustic innovation ) one never knows what the next best thing could be.

Note: this article are for all those young minds, who need to understand that for a better world, one does not have to invent the wheel. Just add the wheel to the cart you make. 

A special thanks to the G-con team, especially – Soumaya, Madhuri, Ananaya, Gaurav, Sahil who helped me think this article.


 

 

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Green Business Ideas – Using Solar Panels as Glass Facade can reduce Heat Island Effect in Cities and earn LEED credits


glass facade

In the past week I was interviewed by two News media both electronic & print which were very excited about a report by scientists from the National Environmental Engineering Research Institute (NEERI) India,  on Glass Façade Buildings in the City of Mumbai, India  and how it is raising the overall temperature by more than 17° C in the surrounding area of the building. Although it could be true, one must explore about how this problem be addressed without making ‘glass’ a bad building material. Things are not always black or white, therefore I would use this as an opportunity to once more showcase how Sustainable Cities  could be planned.

Glass has been a tradition building material for eons now. Colored glass was found from the Babylonian era and some of the most beautiful Churches and Cathedrals draw their prime beauty from the Stained Glass murals. Glass is the only single medium which allows the external environment into the room in a controlled fashion. Which means one can enjoy rain, snow or bellowing wind swaying the tree tops without getting wet or cold and having that curly lock of hair firmly in place.

Yet uncontrolled use of glass can create problems, such as raising the ambient temperature of the city/town and making it warmer. While extensive use of glass in building façade may be considered a good thing to counter the harsh winter experienced in the temperate regions of the World, it is foolish in Hot climes.

The reasons are simple. The word ‘Green House‘ originally meant ( before Global warming became popular) a glass house which kept the temperature warmer than the freezing  European cold and let some plants & vegetables grow. This happens because the heat from the Sunlight gets trapped within the space by the default property of glass.

While this is good for designing a building in say Norway or Alaska, where every drop of Sunlight would bring in the warmth and perhaps help save in reduction of energy consumption required for district heating, the same principle would require enormous amount of  district cooling which otherwise would have been normal in case of a hot and humid city like Mumbai or any other city with similar climatic conditions. And those large  water-cooled Air-conditioning plants placed on the roof tops to cool the buildings do so by pumping cool air inside the buildings while sucking the hot air away and out into the surrounding atmosphere. So a total glass building would not only throw more hot air out into the cityscape it would also use more water to cool itself. Yes, there is air cooled A/c plants too and high-efficiency COP’s have the ‘Green’ label attached but it too consumes energy and heats the sorrounding it however saves on water. Only the most well designed and high-end commercial glass façade buildings conform to all Sustainability criteria. But it does not hold true for all.

Therefore while the building may look swanky and very western, I would caution the tenant in buying space there as their energy bills could shoot up. Moreover by default of design constrains, its cheaper to make the Glass Facade buildings near hermetically sealed. Further no one would want the Air conditioned space to get warm because of a leak in the window casing.

Now the above observations lead to some unique problems for India or for any Emerging Economy in the Third World with similar climatic conditions.

First is the heat & dust. Not only does glass buildings get warmer inside it turns ugly on the outside too because of the perpetual dust. And once the commercial buildings are sold it becomes the building owner association responsibility to take care of maintenance. Maintaining tall glass façade building does not come cheap. It requires a whole new engineering solution, such as façade cleaning lifts and trained people to do it.

Second, we are a ’emerging economy’. Which means only a few rich & super rich have the luxury of having uninterrupted power. Rest are routinely treated with planned load shedding / power cuts and have to generate their own power through fossil fuel smoke belching  Diesel generators. In case of longer duration of power failure, rationing is done to cut cost and even the generators are shut down. And in this case one has no choice but to sit in airless rooms breathing Carbon –Di– Oxide exhaled by the neighboring colleague and hoping to survive the day.

Third, in smaller Tier -II & III towns and even the cheaper business districts within the megalopolis  the buildings only ape the Glass Facade exterior with no  Fire Safety Norms as a priority, and are built by unscrupulous Builder developers who themselves are an ignorant lot along with little or no understanding of EHS ( Environment – Health – Safety ) nor it is understood by the general public. ( the whole of India has only 2-3 dedicated burns center, one in Mumbai. New Delhi has none. However thousands die each year through burn related accidents) . So Glass buildings which are not designed well may lead to catastrophe in case of fire. Further as some are built right upon the road-side in high density areas, during Earthquake or other calamities, it may only compound the problems further with razor-sharp glass falling all over. True the glass have built-in safety feature to shatter into small bits but bad fixing and poor quality glass do not perform as intended.

Business and Scientific report do not go hand in hand. But  Science must be heeded if Business is to thrive. Global warming and its associated risks are too well documented to be ignored.  ( read my article for details:  Climate change – the most significant emerging risks facing the world today ) If the City of Mumbai or any city with similar climatic conditions continues to grow in this fashion and Glass façade buildings become norm and not exception, we are looking at a serious problem.

So we come to the question of what would the Developers and the Public do post reading the NEERI report ? Will tall glass façade building vanish from the cityscape? No chance.

But saving Mumbai ( and other cities ) is a must. Therefore here I will present an alternate thought which the Glass manufactures like ASAI, MODI etc along with the Solar PV manufacturers would I hope discuss over cocktail & dinner and come back with great Eco Ideas which would at least help reduce the problem of Heat Island Effect. And for this we must look at BIPV.

CIS Tower, Manchester

Image via Wikipedia

Building Integrated Photo voltaic (BIPV) has been around for sometime. It produces electricity and can also act as a Glass Facade. (As the image to the right shows, the dark blue glazing with a logo on top )  Now this is an option which has not been explored to its full potential in India and the rest of the World because of the cost verses production of electricity. It is generally understood that BIPV which is still in its nascent stage needs to develop further to truly become the choice for Architects and Builders to consider using it as an alternative to Glazed Building. This can happen only when the cost of the product becomes near equal to that of conventional Double Glazing Unit ( DGU ) which we see all around the city of Mumbai. However we can speed up this process by simply bringing in the economy of scale.

So how does one bring about this economy of scale? Simple, by introducing the Green building concepts which require the use of Solar Power or Green Energy. Both in the TERI – GRIHA  and IGBC -LEED certification process require  to bring energy efficiency of about 14% to the Building Envelope ( skin of the building; the outermost wall /glass surface ) which  at times design constrain and economic factors make  very difficult to deliver. Further Green Building Norms also ask for 10% of the total building energy be drawn from Solar Power. This too, is difficult due to unavailability of required roof-top space in certain cases.

BIPV

Now BIPV  are SPV  (solar photo voltaic) patches of  modules which is sandwiched  between glass.  It not only produces electricity but also reduces the amount of Sunlight from entering the building which is known as the SHG factor for glass ( Solar Heat Gain). So this can act like ceramic frit-glass, which too is an architectural favorite as it has lower SHG factor  and yet have dual function. Further in the Green Building rating system one looks for high SRI  (surface reflective index) content to reduce the heat island effect. Glass has high SRI index. So it reflects more sunlight away and what could have entered the building unhindered gets caught and converted into energy by the SPV cells. So another LEED credit point, credit interpretation could be sought jointly by the SPV as well as the Glass manufacturers.

Now as more and more buildings all around the world are opting for LEED Certification ( Leadership in Energy and Environment Design ), the above two credit points would fit well into the scheme of things. But this may not be enough to reduce the cost of  BIPV. Therefore we can adapt the idea which I have explained (in the article – Green Business Ideas : Cheap Solar Power is possible  ) earlier to manufacture cheaper BIPV’s  and yet creating space for newer research & development. Therefore what NEERI published as a problem can be solved by scientific ways and high-end engineering which follows the basic principles of Sustainable Building Design. And who knows one day we may have enough BIPV clad Green Buildings just as the above French building ( click on image ) which would help further reduce the enormous Carbon Footprint each City has, to make a safer Earth with better business ideas.

 

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Green Business Ideas : Cheap Solar Power is possible


Most Small Companies who are installing roof top Solar Panels are doing so to get the Tax rebate in India. They are also doing it to “earn” Carbon Credits. For the lay business person “earning” carbon credits means “profit”. While it can not be true because the system of Carbon Credit fund is just to improve your IRR, and can’t be found under BUA ; I do not like to discourage this trend. Why? Simple – to earn Carbon Credits one has to do a CDM project. And I love that. Then if it can be proven to be a valid project worthy of Carbon Credit funds, great! By that time they understand that, they do a good job and can see the benefits all around to bother much for the “profit” through CER’s. If they get it its nice but the life-cycle benefits of a Green Building is consolation enough.

But Carbon Credit can become profitable, at least with due diligence and revised thought by the CDM authority. And be given as an incentive to those who would be able to do rural electrification or as in the case of India, provide electricity in tier III towns for a decent time with the help of the wires and cables the Government of the day may have installed during the election years, but forget to insure supply of power on a regular basis once chosen to govern. Not because they chose not too, but during the heat of elections most forget that there is a term – technical and/ or economic feasibility. But when did full truth ever help win an election in the World?

Let us discuss an idea, about how we can make Solar Power at a cheaper cost.

The life of a Solar panel is 25 years, but it is assumed that the efficiency drops to 80% in the 10th year. And by the first five years the RoI is achieved. Now as newer and more efficient panels are being produced, there could be a cause for worry that it would be more and more difficult to sell them, as the traditional first enterprises to take up the challenge and having installed Solar Parks would still be holding on to the “old” SPV for its 25 year life span.

English: On 140 acres of unused land on Nellis...

So how does one make the Solar PV industries grow? How would the cost be covered and  more efficient panels generating more power and consuming less space and lighter in weight too come into the market?

One idea could be by selling old solar panels !   It is a great eco-idea and to encourage this, we need participation from all stake holders.

Second sale is popular in automobile, mobile phone and many products, the market system is mature. All it needs is to tweak it to conform to the SPV industry.

Imagine villages in India, Africa, Brazil and other developing nations who have a huge socio-economic gap among its Peoples and yet are emerging economies of the future; could create a Program of Activities where in a Public -Private partnership can be mooted and a viable business plan developed.

From Village roofing; thus eliminating traditional  thatch roof which is becoming more dearer as communities shift away from agrarian life-style and there is land use change; to community shelters for the destitute sleeping in the cold & rain; to roofing alternatives for very small-scale or cottage industries; to providing power to their electric stoves, thus eliminating the GHG from Gobar Gas plants ( read my article – Renewable Energy – Empowering Women & Saving Forests ) the ideas can be many and each more practical and wonderful than the earlier.

Now add to this the Green Climate Fund and let the project proponents recoup some of their investment ( which is lower to start with in second sale product ) through Carbon Credit.

Hope someone would develop on this idea and present it at the Rio+20.

 

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Solar PV – Record Efficiency reported.


Photovoltaic cells produce electricity directl...
Image via Wikipedia

A company called First Solar has just raised the bar for every other photovoltaic cell manufacturer by setting a record for PV efficiency. First solar, among other things, makes cadmium-telluride (CdTe) solar cells and increased their efficiency to 17.3-percent.

According to First Solar, “…it set a new world record for cadmium-telluride (CdTe) photovoltaic (PV) solar cell efficiency, reaching 17.3 percent with a test cell constructed using commercial-scale manufacturing equipment and materials. The test cell’s performance, confirmed by the U.S. Department of Energy’s National Renewable Energy Lab (NREL), far surpassed the previous record of 16.7 percent set in 2001 … The average efficiency of First Solar modules produced in the first quarter of 2011 was 11.7 percent, up from 11.1 percent a year earlier, and the company has recorded full-module efficiencies over 13.5 percent, with a 13.4 percent module confirmed by NREL. First Solar’s module efficiency roadmap sets a goal for production-module efficiencies of 13.5-14.5 percent by the end of 2014.

Now, this may not sound like a big deal on first glance, but from early 2011 to mid- 2011, First Solar has increased the efficiency of its solar cells from 11.7-percent to 17.3-percent which is a huge leap for an industry that measures itself by one-tenth of a percent increments.

Look, if you’ve read this far then this means I have you a little excited with this news. But, there is even bigger news in breakthrough solar technology. Just two days ago a startup in Santa Clara, California called Alta Devices scored a huge victory by upping its thin-film gallium-arsenide cell to 28.3-percent efficiency.

According to ieee Spectrum, “The key to achieving the record was photon recycling. When the photons in sunlight are absorbed in a photovoltaic material, they split into an electron and a hole. The electrons that pass out of the cell can be used as electricity, but many of them are lost in the semiconductor when they recombine with a hole to produce either waste heat or a new photon. By carefully growing a high-quality single crystal of gallium arsenide, the company managed to ensure that more than 99 percent of the recombination would result in new photons.”

Both of these breakthroughs are exciting developments in the field of solar energy. We are at a tipping point my friend where efficiency goes up and cost comes down to a price that is starting to make solar energy competitive with fossil fuels.

Originally Posted on green tech gazette. Posted by Kevin Green, September 8, 2011

 
 

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