sustainability & life cycle assessment of …...(cdte), and film crystalline silicon).2 however,...

csdCenter for Sustainable Development

Sustainability & Life Cycle Assessment of

Photovoltaics:Manufacturing and Recycling Processes

Werner Lang

picture cover pageminimum resolution 300 dpi

width of the picture not wider than the text blocksheight of the picture minimum 0.6” from last text block

ideally like this frameno frame for the picture

Instructor

Kathryn Chang

The University of Texas at Austin - School of Architecture - UTSoA

Ever-increasing fossil fuel prices and depletion of petroleum reserves are renewing the world’s focus on alterna-tive energy. Sustainability has become one of the most talked-about topics in the world today and in the past few years the installation of solar panels has exponentially increased on roof-tops ranging from city skyscrapers to farm houses. Power from the sun in one day can provide enough energy to meet the world’s electricity needs for a whole year.1 Unlike wind turbines or hydropower stations, PVs are versatile, relatively inexpensive and can har-ness the sun’s energy from anywhere in the world. Aside from the most commercialized silicon wafer technol-ogy, a new generation of low-cost PVs based on thin films of semiconducting materials deposited on inexpensive substrates, will drastically increase the prospects of commercialization (i.e. amorphous silicon, copper indium diselenide (CIS), cadmium telluride (CdTe), and film crystalline silicon).2 However, several factors must be taken into consideration in a product’s

life cycle assessment in order to as-sess its overall sustainability such as its emissions, environmental impacts and recyclability. Installing PVs is not a fix-all for the energy crisis if its embodied energy exceeds that of its power generation capacity, or if the raw materials used cannot be effi-ciently recaptured in the supply chain.

Not only are we already witnessing a change in the way our buildings look but also in the materials and technol-ogy they are built with. This change occurs not due to choice, but rather due to a lack of choice on the prem-ises of global warming and natural resource depletion. Sustainable archi-tecture needs to demonstrate not only high energy performance but also a level of frugality in its material choice. Environmental materials should ad-dress issues of energy conservation, heath hazards, resource management, and waste management. In today’s world, it is no longer enough to just fabricate clean and green products but manufacturers need to close the sup-

Fig. 1 PV Soundless in Freising, Germany. Isofotón. A 500kWp sound-barrier with ceramic based PV modules installed next to the Munich airport.

main picture of presentation

Sustainability & Life Cycle Assessment of Photovoltaics

Kathryn Chang


2


ply chain loop and assume responsi-bility and stewardship of the entire life cycle. The goal is to develop cradle to reincarnation systems3 that can skip the grave stage entirely (Figure 2).

Oftentimes trendy magazines will have a popular article on the “Net Zero” house, but does that mean those homes are truly sustainable? The true measurement of sustainability can only be determined by looking into embedded energy in all of its indus-try sectors including its production, operation and recycling processes. The ecological competitive advantages of using PVs include zero opera-tional greenhouse gas emission, short energy-pay-back time, noiseless, an infinite energy source, and a 25+ year low maintenance life span. Of course, the attractiveness of renewable tech-nologies depends not only on their energy paybacks. Too often, energy technologies are discussed solely in terms of their direct monetary costs without taking into account other costs in the life cycle. They must be taken

together to define the total cost of renewable energy.

Manufacturing PVs

The manufacture of PVs presents risks concerning environmental, health and safety. Brookhaven National Labora-tory, under the US Department of Energy’s National Photovoltaic Pro-

gram has been conducting extensive research and studies on PV’s true impacts and methods of prevention. The issue with regards to decommis-sioning of PV modules at the end-of-life is having the necessary system and infrastructure setup for proper disposal and dismantlement, ensur-ing that the cost of recycling does not escalate the overall cost for the end user. If the total costs of PVs become too high, it would create barriers to market, hindering the transition process from conventional energy to green energy generation.

One of the most important goals of sustainability is resource manage-ment in determining how to get the most from as little as possible. From a materials point of view, the cost of making a solar panel from a recycled one is about the same as from new materials, but on the energy side, it only takes about one third of the energy. Although the quantity need for the recycling of solar panels are relatively low today since solar cells have at least a 25 year life expectancy, it is essential to plan ahead for when they do retire. In effect so that they

Fig. 2 Industrial Ecology and Completing the Loop

Fig. 3 Historical Renewable Energy Consumption by Sector and Energy Source, 2000-2007 (in 1000 Billion Btu) 14


3


can be properly recycled and waste can be minimized. Solar power is a green energy; it is in our hands to ensure this clean form of energy does not leave a dirty legacy. Most recycled panels so far have been flawed or damaged modules recovered by the manufacturer’s warranties. These numbers will trend up as we approach 2015 as the first generation of solar panels will come to their end-of-life. About 16,000 metric tons (35,280 lbs) are expected to be recycled in Europe by 2015, compared to just 2,000 metric tons (4,410 lbs) last year.4

Potential Risks

Currently little attention is paid to the potential risks associated with the scaling up of solar panel production in the near future. The solar power industry must address these ques-tions immediately or risk repeating the mistake of the microelectronics in-dustry with regards to e-waste, which has caused death and injury of factory employees and people living in nearby regions.

Reported in March 2008, one plant in China’s Henan province has been dumping a toxic byproduct from its polysilicon manufacturing process on nearby farmlands. The toxin, silicon tetrachloride, makes the soil too acidic

for plant life, also causes severe irrita-tion to living tissues and is highly toxic when ingested or inhaled. Regulators suspect that firms in other developing countries are taking similar short-cuts.5 International regulatory policies need to be set in place to avoid further damage to other parts of the world where local policies are lax.

Recycling Initiatives

The solar power industry is already taking lessons learned from the mi-croelectronics industry in coming up with similar initiatives to the Extended Producer Responsibility (EPR), which are policies that provide incentives for companies to design and produce cleaner and more easily recyclable products, while discouraging the prac-tice of “planned obsolescence” (inten-tionally making products that quickly become out of date or useless).6

An initial conclusion might be to recycle solar PV panels with toxic metals at existing e-waste recycling facilities or at facilities that recycle batteries containing lead and cad-Fig 4. Two Types of PV Production Process

Fig. 5 Life Cycle Emissions from Silicon and CdTe PV Modules15


4


mium. This method will keep toxics out of the municipal incinerators and landfills. Unfortunately, however practical as it may seem initially, most of these low-tech and environmentally heavy foot-printed recycling facilities reclaim metals using smelters, which are known to increase the risk of lung cancer from cadmium exposure in recycling workers and residents in nearby communities.7

In order to produce a real solution to solving the potential problem of solar cell recycling, we have to look in both directions in the supply chain. Sheila Davis, en executive director of the San Jose nonprofit group that pushes for green practices in the technology sec-tor, suggests that “developing benign substitutes for some of the most dangerous materials [is] essential for the solar industry to be truly sustain-able.”8

Organic PVs

Alternatives to current mainstream PVs are an emergent technology of organic PVs that has spurred the interest of venture capitalists with promise of a much cheaper and more versatile source of solar power. Organ-

Fig. 7 PV Section

Fig. 6 EPBT for Silicon PV12

ic PVs employ carbon-based plastics, dyes, and nanostructures and can be manufactured via a printing process. Compared with the high-temperature vacuum processing used for normal PV semiconducting materials, it can be a huge savings along the value chain. This kind of PV is significantly more flexible and lighter than inorgan-ics, leading to a large array of possible uses (i.e. portable battery chargers,

power-producing coatings for roof shingles, tents and vehicles). The highest known energy-conversion ef-ficiency of organic PV is in the range of 6.5%. Due to its lower manufacturing cost, organic PV developers are aim-ing to target lower efficiency demand markets like coatings for rooftop ap-plications. However, until the technol-ogy can become robust and powerful enough for full commercialization, we have to concentrate on resolving the issues with proper disposal and recycling of mainstream PVs.9

Embedded Energy and EPBT

The economics of measuring energy consumption in PVs is by means of comparing individual energy pay-back times. Energy pay-back time is defined by

Fig. 8 EPBT for Thin-Film Systems13


5


EPBT = Einput/Esaved,

where Einput is the energy input during the module life cycle (which includes the energy required for manufactur-ing, installation, operation, and energy needed for decommissioning) and Esaved the annual energy savings due to electricity generated by the PV module (figure 4).10 The most commercialized type of PV cells are produced by using crystalline silicon technology capable of energy-conversion efficiencies between 12-17%. A super thin slice of high-purity silicon wafer is used as semiconductor to capture sunlight energy and convert it into useable electricity. EPBT for Silicon PVs are shown in figure 6. There are also thin-film PVs (figure 8) having comparative-

ly lower efficiencies between 5-13%, which is compensated by also lower production costs. Crystalline silicon can be subdivided into monocrystal-line silicon (mono c-Si), multicrystal-line silicon (multi c-Si). Thin-films can be distinguished by the type of the semiconductor layer: amorphous silicon (a-Si), cadmium telluride (CdTe) and copper indium diselenide (CIS).11 The manufacturing stages of

silicon PVs and a CdTe thin-film PV are illustrated in figure 3.

Centralized vs. De-centralized Strategies

The amount of waste generated from manufacturing PVs decreases as the operation of the facility reaches a steady-state level of production (Figure 10). The immediate needs of waste disposal and recycling of PVs can be solved by either centralized or de-centralized approaches, however, as the PV industry begin to scale up, future needs would be more economi-cally solved by centralized strategies. The main differences between the two strategies are scale and method of metal recovery (Figure 9). The central-ized scheme targets a much larger scale application in smelting facilities which use glass as a fluxing agent and reclaim most of the metals by incorporating them in their product streams. In the de-centralized dis-persed operations, it is more expen-sive due to the small quantities and high transportation costs. For the long term, it would be more efficient to separate the PV layers from the glass substrate as an initial step to minimize the amount of waste generated, a potential of three orders of magnitude in waste reduction.17

Battery and Electronics Industry

Large electronics and telecommunica-tions companies (i.e. AT&T) recycle a wide range of products through the combination of in-house collection with collection by reverse logistics companies who provide collection, consolidation, pre-processing and transportation services. The collected products go through at least one of three processes of refurbishment for resale, disassembly for spare parts

Fig. 10 Projected PV Retirement Rate -Tons/Year vs. Year of Use

Fig. 9 Centralized vs. De-centralized Strategies


6


or dismantlement for reclaim materi-als. The driver behind recycling in the electronics industry is the salvage value of the usable components and precious metals.18

Another industry worth comparing to is the NiCd battery industry. The Por-table Rechargeable Battery Associa-tion (PRBA), a consortium of industry manufacturers, funds and overseas a non-profit take-back program that utilizes centralized collection and recycling facilities. The PRBA works closely with the International Metals Reclamation Company, Inc. (IN-METCO), an integrated stainless steel recycler, capable of recovering nickel and iron from NiCd batteries and sell-ing Fe-Ni-Cr alloy back to the stain-less steel industry. INMETCO can also recover high-purity cadmium which is returned to the NiCd industry.19

Recycling of solar panels is much more complicated than that of the products mentioned in the industries above. Unlike these other products, PVs have a very long operational life span between its fabrications and recycling stages. The infrastructure for collecting and recycling of used products in similar industries can be accounted for in three generic para-digms: utilities, electronics, and bat-tery paradigms. Applying these para-digms to the PV industry can provide us with a picture for the possibilities of solar cell collection and recycling.

In the first scenario, institutional end users (i.e. electric utilities) would be the main owner and servicer for their large PV systems. It is under their responsibility to bring back their spent modules to the recycler. The recycling costs would be embedded in the rates charged by the utility company.

The second scenario involves copying the battery industry where manufac-turers would be collectively respon-sible for the consolidation and delivery of spent modules to a collectively sup-ported PV recycler. Parts or materials outputted from the recycling entity would be sent directly to smelters and other specialized recyclers, under a pre-paid transportation agreement.

Third scenario mimics the recycling process that of the electronics in-dustry. Each manufacturer would be responsible for the collection, trans-portation of obsolete modules to recy-clers. The manufacturer would have an escrow fund set aside when the PV modules were initially purchased to ensure available funds when those panels reach end-of-life (see First Solar Case Study).

Recycling Challenges

PV installations are not concentrated in most cases—neither by geography nor by component content. Demands for PVs are currently dominated by dispersed installations all over the world. Even large area arrays are not typically centralized in one locale. Small residential applications are far more scattered across the globe. The collection process poses potential challenges and high cost. Unlike the electronics and battery industry where value of reclaimable material are

high, PVs lack significant quantities of any key material, which can deter its materials recovery from an economics point of view. For instance, the most costly of the thin-film constituents, in-dium, accounts for only 2.5-5% of the total value of an CIS PV module.20

Existing Recycling Technologies

According to PV Cycle, there are cur-rently two processes in the market operating at full-scale: the Deutsche Solar treatment process and First Solar’s treatment process. The differ-ence is mainly in the types of modules each process targets. Deutsche Solar treats mainly the recycling of crystal-line silicon modules and First Solar is mainly used for CdTe modules. In both cases, glass and other metals can be separated and distributed to additional recycling facilities for further extrac-tion.

Recycling x-Si Modules

First Solar Inc. can also recover crystalline Si wafers from used x-Si modules. The process involves heat-ing and removal of the backsheet, and then vaporization of the EVA lamina-tion layer. The solar coupons can then be recovered, this method yields slightly lower electrically efficient solar panels than unused ones from 12.8% to 10.73%. First Solar is opti-mistic that this can be improved in the

Fig. 11 Disassmbling PV

Fig. 12 Multicrystalline PV Modules


7


near future.21

Recycling CdTe Modules

First Solar Inc. starts with disassem-bly of the module and recovery of lead wires and then the module parts are separated during different times of a milling process. Glass is stripped of metals in successive chemical disso-lution steps, mechanical separation, and precipitation or electrodeposi-tion. At end of process First Solar has a recovery of >80% of the tellurium in CdTe PV panels and 100% of the mounts, glass and EVA parts. The leftover metals including Cd, Te, Sn, Ni, Al, Cu are sent to INMETCO for ad-ditional recovery.22

Recycling CIS Modules

Drinkard Metalox Inc. has developed operations for recycling CdTe and CIS

modules involving a chemical strip-ping of metals and EVA along with successive steps of electrodeposition and evaporation to recover the rest of the metals. It reports a recovery of 95% of Te and 96% of Pb from the CdTe modules. Drinkard Metalox Inc. also uses a chemical stripping process leaving the SnO2 semi-conducting layer intact on the glass substrate, essentially making the substrates reusable for PVs.23

The cost of collection and disposal or recycling is directly proportional to the weight of the recycled materials. In or-der to make PVs more economical and better for the environment, modules need to be easy to disassemble, sepa-rate into recyclable materials from its main glass substrate. An important contributor in the research and devel-opment of PV recycling is Professor Vasilis Fthenakis, founder and director of the Center for Life Cycle Analysis at Columbia University. He also leads the National PV Environmental Health and Safety (EHS) Research Center operat-ed out of the Brookhaven National Lab (BNL) under the sponsorship of the US Department of Energy. Fthenakis sees that an alternative to consolidated recycling strategies is on-site separa-tion. More research and development needs to go into the industry to create PVs that can be taken apart at the time of dismantlement.24

Case Study: Dow Corning

Although Dow Corning is not a PV manufacturer, it is an important sup-plier for the PV assembly. Dow Corn-ing supplies companies like Hemlock Semiconductor Group with silicon-based materials for solar applications. In Dow Corning’s Wiesbaden site in Germany, employees can witness their own products in solar panels work-ing and helping produce more green and sustainable goods. Over 1,000 m2 of PVs were installed on the roof and facades of the office and produc-tion buildings to replace conventional energy that would otherwise come from coal plants on the grid. The energy generated by these PVs are fed back into the local grid, in return, Dow Corning benefits from subsidies to purchase electricity for its own energy demands. The German subsid-iary commits to reinvest 30% of these subsidies every year in sustainable energy project aiming to reduce the plant’s total energy consumption. The energy generated by the roof top pan-els is equivalent to the average annual energy consumption of 35 families of four.25

Case Study: First Solar Inc.

First Solar is one of the frontiers in establishing a cradle to cradle pro-cess within their solar module sup-ply chain. First Solar has established industry’s first comprehensive, pre-funded module collection and recy-cling programs. In order to maximize

Fig. 13 Solar panel in Brooklyn. Cadmium telluride photovoltaics

Fig. 14 CdTe PV Panel in Dubai

Fig. 15 Dow Corning Facility in Wiesbaden, Germany

Fig. 16 First Solar Manufacturing Plant


8


Fig. 18 Life Cycle of PV Modules

recovery of valuable materials for use in new modules and minimize environ-mental impacts, they have developed a module that is approximately 90% recyclable. The end user can request collection of First Solar’s modules at any time during its life at no additional cost to the end user. The prefunded amount paid by the user upfront is es-timated based on forecasted recycling costs at the end-of-life after 25 years. Each of their current three global manufacturing facilities have recy-cling facilities built in so no additional infrastructure is needed to close their supply chain loop.

First Solar’s prefunded recycling pro-gram involves a trust structure estab-lished in custodial accounts with the name of a trustee so that the funds will be available regardless of First Solar’s future financial status. Only the trustee can distribute the pre-funded amounts and these funds cannot be accessed for any other purpose other than for administering module collec-tion and recycling. To further embed trust in First Solar’s customers, the financing arrangement is periodically audited by third-party auditors.26

Case Study: PV Cycle

Founded in 2007, PV Cycle’s mission is to “implement the photovoltaic indus-try’s commitment to set up a volun-tary take back and recycling program for end-of-life-modules and to take

responsibility for PV modules through-out their entire value chain.” (Figure 18) With the same goals in mind as the rest of the solar industry in trying to stay ahead of regulators, PV Cycle has teamed up with 79 full members and 14 associate members including Q-Cells, Sanyo, GE Energy, Sharp, Kyoc-era and First Solar, as well as German solar industry association BSW and the European Photovoltaic Industry Association (EPIA). Together the asso-ciation represents 85% of Europe’s PV market (Figure 20). Through PV Cycle, the solar industry hopes to install an all encompassing waste management and recycling system that can achieve the highest economical feasibility and environmental responsibility.27

PV Cycle’s take-back and recycling program involves a two phase scheme. The first phase is reserved for all the

Fig. 17 Broken Pieces of Multicrystalline Silicon Wafers

necessary preparatory work to solicit onboard industry participants, design the network and infrastructure, and coming up with program objectives. The latter phase encompasses the implementation of the program and scheduled annual auditing to moni-tor progress towards achieving the program goals.28

Conclusion

After comparing the emissions from the life cycle of the four major com-mercial PV technologies (Mono-, Multi-Silcon, CdTe, CIS), the results indicate that their differences are in-significant in comparison to the emis-sions that they replace. By substituting conventional power generation with PV systems we gain enormous envi-ronmental benefits. Centrally installed CdTe PVs alone amount to 89-98%


9


reduction of greenhouse gas emis-sions, pollutants, heavy metals, and other harmful impacts. Residential or commercial dispersed installations, on the other hand, experience an even greater reduction since transmission and distribution network infrastruc-tures are virtually avoided completely. In general, thin-film PVs require less energy in their manufacturing than crystalline Si PVs, which translates to the lower total overall emissions of heavy metals.

The solar panel industry is work-ing towards long term strategies in preserving the environmentally friendliness of PVs. Investigations of options to best treat the disposal and recycling of spent solar panels are underway. Research and develop-ment has shown that recycling solar panels is technically and economically feasible; however, caution needs to be taken with regards to accounting the environmental effects of the whole life cycle. Emergent solutions and pilot programs are in place already to seek out the best option for resolving the recycling problem of PVs both in

Europe and U.S. Other companies not directly part of the PV life cycle are be-coming external pioneers joining the loop by taking the first steps, through replacing conventional energy source from the grid with PVs, thus putting truly sustainable and green products on the market.29

The eventual integration of solar

energy generation to the developing concept of the “Super Smart Grid” is certain. The idea behind this concept originates from the European Union’s decision to reduce greenhouse gas emissions by 20-30% and Germany has a target of 40% for 2020. The EU aims to reduce emissions by 80% when 2050 comes around. EU has also decided on increasing the use of re-newable energies to 20% of total ener-gy consumption in 2020. With Europe’s current energy policy paradigm, it would be difficult to achieve these tar-gets. One of many possible solutions for Europe’s energy would be to utilize the solar and wind energy potential in the desert of North Africa (Figure 19) “Renewable electricity from North Africa would be sufficient to satisfy the electricity needs of the Mediterranean and the rest of Europe many times over,” according to the Super Smart Grid website.30 Besides introducing new infrastructure to transmit power over the Mediterranean Sea, the PV industry needs to also collaborate with other power nodes on the grid to plan and establish a feasible integration

Fig. 20

Fig. 19 Average Daily Radiation in kWh/sq m per day


10


solution. PV cell developers should also work towards designing better assemblies of PV modules that can be easily disassembled for recycling. PV technology needs to develop further to obtain better efficiencies, in turn increasing its marketability.

The PV industry should seek to re-place all of its conventional energy sources with solar cells and other more alternative energy. In the future, we will have PVs that are made by the clean energy generated by other PVs. The next step for the solar industry is to convert its full value chain to us-ing green energy to produce a more sustainable life cycle for PV technol-ogy. The PV industry should seek to replace all of its conventional energy sources with solar cells and other more alternative energy. In the future, we will have PVs that are made by the clean energy generated by other PVs. The next step for the solar industry is to convert its full value chain to using green energy to produce a more sus-tainable life cycle for PV technology.

Notes

1. “Dow Corning helps meet future solar industry needs - Dow Corning .” Dow Corning Silicones - Dow Corning . http://www.dowcorning.com/content/solar/solarworld/solarfuture.aspx (ac-cessed July 7, 2010).

2. Fthenakis, Vasilis M.. “End-of-life management and recycling of PV modules.” Energy Policy28, no. 14 (2000): 1051-1058.

3. Manahan, Stanley E. Environmental Science and Technology: A Sustain-able Approach to Green Science and Technology, Second Edition. 2 ed. Boca Raton: CRC, 2006.

4. Ibid.

5. Dickerson, Marla. “Solar energy’s darker side stirs concern - Los An-geles Times.” Featured Articles From The Los Angeles Times. http://articles.latimes.com/2009/jan/14/business/fi-notsogreen14 (accessed July 7, 2010).

6. A Silicon Valley Toxics Coalition White Paper. “Toward a Just and Sustainable Solar Energy Industry.” Published January 14, 2009.

7. Ibid., p. 22.

8. Dickerson, Marla. “Solar energy’s darker side stirs concern - Los An-geles Times.” Featured Articles From The Los Angeles Times. http://articles.latimes.com/2009/jan/14/business/fi-notsogreen14 (accessed July 7, 2010).

9. Fairley, Peter. “IEEE Spectrum: Solar-Cell Squabble.” IEEE Spectrum Online: Technology, Engineering, and Science News. http://spectrum.ieee.org/energy/renewables/solarcell-squabble (accessed July 6, 2010).

10. “Energy Pay-Back Time (EPBT) and CO2 mitigation potential.” Ecoto-pia. http://www.ecotopia.com/apollo2/pvepbtne.htm (accessed July 7, 2010).

11. Other types of PV technologies are also available with less market share, however, this paper aims to analyze and examine the more widely commercialized PV technologies in regards to possibilities for recycling.

12. Fthenakis, V. and E. Alsema, Photovoltaics Energy Payback Times, Greenhouse Gas Emissions and Ex-ternal Costs: 2004–early 2005 Status. Progress In Photovoltaics: Research and Applications, 2006. 14(3): p. 275-280.

13. Ibid.

14. Wong, Peter. “EIA Renewable Energy-Solar Photovoltaic Cell/Mod-ule Manufacturing Activities.” U.S. En-ergy Information Administration - EIA - Independent Statistics and Analysis. http://www.eia.doe.gov/cneaf/solar.renewables/page/solarphotv/solarpv.html (accessed July 7, 2010).

15. Emissions from Photovoltaic Life Cycles. Vasilis M. Fthenakis, Hyung Chul Kim, Erik Alsema. Environmen-tal Science & Technology 2008 42 (6), 2168-2174

16. Ibid.


18. Ibid., p. 8.

19. Ibid., p. 2.

20. Ibid., p. 2.

21. Fthenakis, V.M., and P.D. Mos-kowitz. “The Value and Feasibility of Proactive Recycling, National Photo-voltaics (PV) Environmental Research Center, Energy Sciences & Technol-ogy Department (EST).” Brookhaven National Laboratory - A Passion for Discovery. http://www.bnl.gov/pv/abs/abs_142.asp (accessed July 7, 2010).

22. Ibid., p. 6.

23. Ibid., p. 6.

24. “Center for Life Cycle Analysis (CLCA) at Columbia University.” Cen-ter for Life Cycle Analysis (CLCA) at Columbia University. http://www.clca.


11


columbia.edu/people.html (accessed July 7, 2010).

25. “Dow Corning helps meet future solar industry needs - Dow Corning .” Dow Corning Silicones - Dow Corning . http://www.dowcorning.com/content/solar/solarworld/solarfuture.aspx (ac-cessed July 7, 2010).

26. First Solar Inc. 2009. Annual Re-port 2009.

27. “PV Cycle: About PV CYCLE.” PV Cycle: Home. http://www.pvcycle.org/index.php?id=9 (accessed July 7, 2010).

28. “PV Cycle: Voluntary Take Back Scheme.” PV Cycle: Home. http://www.pvcycle.org/index.php?id=44 (ac-cessed July 7, 2010).


30. “SuperSmart Grid (SSG).” SuperS-mart Grid (SSG). http://www.supers-martgrid.net/ (accessed July 9, 2010).

Figures

1. EPIA Market Publication, 2009.

2. Manahan, Stanley E..Environmental Science and Technology. 1 ed. Boca Raton: CRC, 1997.

3. Wong, Peter. “EIA Renewable En-ergy-Solar Photovoltaic Cell/Module Manufacturing Activities.” U.S. Energy Information Administration - EIA - Independent Statistics and Analysis. http://www.eia.doe.gov/cneaf/solar.renewables/page/solarphotv/solarpv.html (accessed July 7, 2010).




7. http://www.firstsolar.com/en/prod-uct_design.php




11. http://spectrum.ieee.org/green-tech/solar/breakthrough-in-captur-ing-lost-energy-in-solar-cells

12. http://www.eia.doe.gov/cneaf/solar.renewables/page/solarphotv/solarpv.html

13. http://www.nytimes.com/2008/02/26/science/26obsola.

html?_r=3&ref=science&oref=slogin&oref=slogin

14. http://www2.epia.org/images/pho_profiles_A/pho_profiles_A_44.jpg

15. http://www.dowcorning.com

16. http://www.firstsolar.com/en/in-dex.php

17. www.uslpv.com/

18. http://www.pvcycle.org/index.php?id=22

19. http://spectrum.ieee.org/green-tech/solar/how-free-is-solar-energy

20. http://www.pvcycle.org

References

http://www.supersmartgrid.net/

http://spectrum.ieee.org/green-tech/solar/how-free-is-solar-energy

http://www.epia.org/publications/epia-publications.html

http://www.findsolar.com/index.php?page=rightforme

http://www.solarpaces.org/Library/csp_docs.htm

http://www.bnl.gov/pv/abs/abs_142.asp

http://www.electronicstakeback.com/index.htm

sustainability & life cycle assessment of …...(cdte), and film crystalline silicon).2 however,...

Documents