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Champions of Photovoltaics Technology

Solar PV technology owes its existence as we know it to Edmund Bequerel, Albert Einstein, and other historical figures. Today, this spirit of technological advancement and ingenuity is alive and well.

The photoelectric effect was first noted by a French physicist, Edmund Bequerel, in 1839, who found that certain materials would produce small amounts of electric current when exposed to light. In 1905, Albert Einstein described the nature of light and the photoelectric effect on which photovoltaic technology is based, for which he later won a Nobel prize in physics. The first photovoltaic module was built by Bell Laboratories in 1954. It was billed as a solar battery and was mostly just a curiosity as it was too expensive to gain widespread use. In the 1960s, the space industry began to make the first serious use of the technology to provide power aboard spacecraft. Through the space programs, the technology advanced, its reliability was established, and the cost began to decline. During the energy crisis in the 1970s, photovoltaic technology gained recognition as a source of power for non-space applications.

Also read, from the Champions of Photovoltaics issue:

A salute to champions of photovoltaics today

Champion photovoltaic companies and labs

Champion advocates of solar

Champion investors in photovoltaics

China dominates economic development in solar PV space

In this section, we salute a few of the technologists that have made this incredible journey possible, and those who have more recently joined the incredible worldwide effort that is making PV a viable competitor to existing power generating technologies.

To get a better understanding of what today’s top technologists see as the key drivers and challenges in PV today, we asked them to answer take a few questions about the major trends in the photovoltaics/solar power industry today, and key challenges facing the industry not only in terms of technology, but in economics and politics as well.

Charlie Gay, Applied Materials

Charlie Gay was named president of Applied Solar and chairman of the Applied Solar Council at Applied Materials, Inc. in 2009. Gay is also a co-founder of the Greenstar Foundation, an organization that delivers solar power and internet access for health, education and microenterprise projects to small villages in the developing world. Greenstar has been recognized for its innovation by the World Bank, the Stockholm Challenge, the Technology Empowerment Network and the Tech Museum Awards.

Gay began his career in 1975 designing solar power system components for communications satellites at Spectrolab, Inc. and later joined ARCO Solar, where he established the research and development program and led the commercialization of single crystal silicon and thin film technologies. In 1990, Gay became president and chief operating officer of Siemens Solar Industries and from 1994 to 1997, he served as director of the U.S. Department of Energy’s National Renewable Energy Laboratory, the world’s leading laboratory for energy efficiency and renewable energy research and technology. In 1997, Gay served as president and chief executive officer of ASE Americas, Inc., and in 2001 became chairman of the advisory board at SunPower Corporation.

Gay has a doctorate degree in physical chemistry from the University of California, Riverside. He holds numerous patents for solar cell and module construction and is the recipient of the Gold Medal for Achievement from the World Renewable Energy Congress.

We asked Gay to answer take a few questions about what he saw as the major trends in the photovoltaics/solar power industry today, and key challenges facing the industry in terms of technology as well as economics and politics. Here’s what he said:

“As you know, I’ve been in this industry for 35 years, and I’ve seen a lot of promising starts that didn’t amount to much. This time is different: we’ve entered the zone of inflection and LCOE is competitive to gas-firing plants at 15 cents kWh, with more than 50% drop in just the last three years. It’s very, very gratifying to watch this transpire.

“Moving forward, the industry will continue to drive down cost-per-watt, largely through increasing the conversion efficiency and reducing manufacturing costs. As we advance efficiencies, we need to tighten integration of equipment, materials and process. To do this will require greater sophistication and automation for line balancing yield management, materials handling and integrated MES.

“Meanwhile, a lot has been written about China as a producer of PV wafers, cells and modules. It’s a trend we are watching unfold this year, with over 80% of new orders originating in Asia, dominated by China. They are also becoming a leading consumer of solar PV energy as the Chinese government has been active in putting a policy framework in place to emerge as a #1 consumption market.” Gay said.

As far as major technical challenges facing the photovoltaics industry moving forward, Gay said these are primarily associated with the need for higher efficiencies and increased manufacturing productivity.

“Regarding conversion efficiencies, most roadmaps are being implemented on a continuum of technical improvements. Today, using screen printing technology, innovative double printing techniques are making contact lines ever finer, minimizing the amount of light blocked from getting into the solar cell. We’ve also entered the stage of expanding the use of selective emitters, some of which are facilitated by screen printing and by new materials for forming the junction.

“We’re also seeing the back of the cell receive more attention for various kinds of back contact configurations where more reflective metallization is possible through simplified back etching of cells, and the high reflectance properties of using aluminum.

“As we strive to improve efficiency, another area being looked at is minimizing surface recombination. Surface recombination of course happens on the front and the back of the solar cell, and we’re developing unique solutions that allow optimal processing for both front and to back properties where the different conductivity types require different film properties.

“Beyond process, there is also a movement toward improving factory automation for better metrology and inspection -- and the capability to make and handle thinner wafers, which helps bring down the direct cost of materials in the use of silicon.

“This next generation of PV solar is really a solutions game that far more complex than just tool making. And it’s precisely why I joined Applied Materials. Applied has the unique perspective and experience to deliver precisely these kind of manufacturing solutions to market, having successfully done the same for both the semiconductor and display industries.

“Now it’s solar’s turn to move from boutique to mainstream. I remember when it took the industry a week to manufacture a single megawatt. Today the industry can crank out a megawatt in 30 minutes,” he said.

What are the major economic/policy/regulation challenges facing the photovoltaics industry moving forward? Gay said a number of specially crafted policies and incentives are needed to create a more robust foundation for growth. “For example, strong government support for renewables in Germany and China has turned these countries into global leaders in this market. However, despite the economic and global policy challenges and uneven progress worldwide in 2009, the market for solar PV grew 60% year-over-year and the outlook for 2010 remains positive. We’re expecting a range of 30-50GW of new manufacturing capacity to be added over the next three years. So we believe that the solar market is still very dynamic and poised to grow,” Gay said.

Daniel M. Kammen, U of California, Berkeley

Daniel M. Kammen is the Distinguished Professor of Energy at the University of California, Berkeley, where he holds appointments in the Energy and Resources Group, the Goldman School of Public Policy, and the department of Nuclear Engineering. Kammen is the founding director of the Renewable and Appropriate Energy Laboratory (RAEL) and the co-Director of the Berkeley Institute of the Environment. In April 2010 Kammen was named by Secretary of State Hilary R. Clinton to be the first Clean Energy Envoy to the Americas.

Kammen received his undergraduate (Cornell A., B. ’84) and graduate (Harvard M. A. ’86, Ph.D. ’88) training is in physics. After postdoctoral work at Caltech and Harvard, Kammen was professor and Chair of the Science, Technology and Environmental Policy at Princeton University in the Woodrow Wilson School of Public and International Affairs from 1993 to 1998.

He then moved to the University of California, Berkeley. Kammen directs research programs on energy supply, transmission, the smart grid and low-carbon energy systems, on the life-cycle impacts of transportation options including electrified vehicles and land-use planning, and on energy for community development in Africa, Asia, and in Latin America. Daniel Kammen is a coordinating lead author for the Intergovernmental Panel on Climate Change (IPCC), which won the Nobel Peace Prize in 2007. Kammen is the co-developer of the Property Assessed Clean Energy (PACE) Financing Model: energy efficiency and solar energy financing plan that permit installation of clean energy systems on residences with no up-front costs. PACE was named by Scientific American as the #1 World Changing Idea of 2009 (co developer with Cisco’s DeVries). Kammen serves on the National Technical Advisory Board of the U. S. Environmental Protection Agency. He hosted the Discovery Channel series ‘Ecopolis, and had appeared on Frontline, NOVA, and twice on ’60 Minutes’. Kammen is the author of over 220 journal publications, 4 books, 30 technical reports, and has testified in front of state and the US House and Senate over 30 times.

Kamen said he’s very excited two trends in the photovoltaics/solar power industry today. “One is the steady push for $/watt parity with fossil fuels, through cost/watt innovations, building integrated cells, and markets that reward peak demand coincidence. The incredible wave of technical innovations in conventional cells, thin-film, and nano-solar technologies make this a very hopeful path,” he said. “The second is a broader push to rationalize energy markets so that rates reflect both externalities (e.g. the REGGI carbon market, and California's soon-to-be-launched one) and actual supply and demand -- real-time pricing -- and both are vital innovations that reward clean energy, and in many ways solar in particular.”

Kammen said the biggest technical challenge facing the industry is low $/watt, not necessarily highest efficiency. “Thin film solar, and nano-solar both show incredible potential, and what is really needed are the sustained research support -- both from the public and private sectors -- to bring these to market,” he explained.

The major economic/policy/regulation challenges facing the photovoltaics industry moving forward? “Clearly we have to overcome the up-front cost barrier, which is why I've been working so hard on PACE financing (see as this make the up front funds available to break the cost/lifetime logjam
that keeps solar out of everyday energy and construction markets,” Kammen said. “ALL new homes come with a solar option, built into the overall cost.”


Terry Bailey, Soliant Energy

Dr. Terry Bailey is president, chairman and CEO of Soliant Energy. Prior to leading Soliant Energy, Bailey spent five years with Evergreen Solar as Senior Vice President of Marketing and Sales. While at Evergreen Solar, he participated directly as part of the senior management supervisory team in the conception, design and execution of several solar factories. Specifically these included a 100MW solar wafer factory located in Wuhan, China; a 450,000 sq. ft., 160MW factory located in Devens, MA, consisting of three distinct fab areas for solar wafer production, solar cell production and solar module production; and two wafer, cell and module fabs of 30MWp and 60MWp respectively located in Thalheim, Germany. These efforts grew Evergreen's (and German joint venture EverQ's) sales from 3MW per year to 250MW in four years, and created a total backlog of over 1GW of take-or-pay orders, representing $3 billion of value.

Bailey earned a Ph.D. in analytical chemistry from Florida State University, specializing in nuclear magnetic resonance research and computer system graphics integrations. He holds a B.S. in Chemistry from the University of Alabama.

Bailey said while there are many trends that could be detailed, two stand out in his mind: Maturation and stratification. “While certainly still an infant compared to the power industry as a whole, PV is beginning to settle into the existing structures and no longer must run maverick all the time versus the entrenched technologies and utilities. As a result of both governmental programs and pressures, and hopefully enlightened self interest, the utilities are structuring ways to integrate and properly utilize the intermittent renewable energy sources, including solar. Slowly, banks and other sources of financing are coming to understand PV and therefore how to value it and provide capital appropriately to those wishing to deploy PV. This is certainly simpler and more advanced in Europe, but even in the US there are welcome trends in this direction. The companies in our industry which are pioneering PPA structures and then evolving them to optimally fit the market requirements are creating increased value, not only for themselves but for the industry in total. Our little ecosystem is still fragile but is finding its fit within the larger macro environment to ensure long term sustainability, rather than bursts of activity generated almost solely from governmental largesse.

“The solar power industry can be discussed at the gross macro level, but the interesting trend is the appropriate stratification which is occurring as part of the natural evolutionary development, Darwinian PV if you will. An overriding driver of the industry is and should be to reduce the cost per kWh generated, but layered on top of this is stratification of the different solar power technologies into market and application slices where they best fit. This stratification is not perfectly clean, not will it be so in the near future, but the trend is certainly there based on the core performance differentials for different technologies as well as the ever present pressures of government. A few examples may suffice to make the point.

“If there is a specific demand for a very high energy output, with local energy storage then a molten salt heliostat based system may be the best solution, but you would certainly never put this in or near a heavily populated area, nor of course in an area with low DNI. If you have unlimited land space, and no restrictions on shading the ground beneath, perhaps a thin film based array would best suit the requirements. However if there is a requirement to maintain agricultural capability beneath a PV array, and there is sufficient DNI, then a high concentration PV solution would fit best. If you have limited area, such as on a commercial rooftop, land fill etc and the desire is greatest energy density, or max kWh/kW installed then a specialized rooftop high concentration PV solution would fit best in a good DNI area.

“So while a general purpose, lowest cost least common denominator PV solution is certainly dominant in many areas, evolution has taught us that in specialized habitats the winner is a specialized solution. The point is that there is no one right answer, but a more right answer for each application and different technologies stratifying in this way is a natural and beneficial path for solar power in general as it takes its place more prominently in the overall power industry,” Bailey said.

In terms of major technical challenges facing the photovoltaics industry, Bailey agrees that cost per Watt rises above all else. “While there are innumerable individual technical challenges for each different form of PV, at the top level the overriding challenge will remain reducing the LCOE, or cost per kWh delivered by solar, such that the initial capital costs of an installation are readily perceived as nominal and acceptable to the market. In general of course this means continually reducing costs, increasing performance, or preferably both. It is important to note that cost reduction should absolutely not be looked at as solely at the PV panel level. In the end the cost which matters is the total installed system cost. Therefore it is both permissible and desirable for changes at the panel level which may add cost, but which allows for a net reduction in the total installed system cost. Of course the various pieces of the value chain must appropriately share in the benefits or there is no real reason for panel manufacturers to add cost to their product,” Bailey said.

More specifically, Bailey sees the following challenges as critical:

  • Thin film generally should have a COGS advantage but must continue to dramatically increase solar conversion efficiency to take advantage at the total installed system cost and LCOE levels and stay ahead of others. Depending on the specific thin film technology discussed then there are also issues to be solved to perfect the form factor of the product, flexible for some applications for instance, while maintaining extremely long working lifetimes of the product.
  • Crystalline silicon is approaching the practical limits of performance without some radical breakthroughs. For this technology continued reduction of COGS is the primary challenge. There are some efforts to effect this not just with decreased silicon costs and base performance but semi-passive low concentration schemes.
  • High Concentrating PV must continue to exploit the significant solar efficiency advantage offered by multi-junction cell technology. There is increasing participation by companies, both start-up and extremely large, in pushing the limits of this cell technology well beyond the current ~40% efficient cells being sampled. Many roadmaps from these companies show paths to ~50% cells in the reasonable future. High concentration PV by definition means two axis tracking is required, so continued technical development in trackers and form factor is required in order to reduce COGS while maintaining pointing tolerance sufficient to service continually increasing concentrations levels of 1,000X and more.

The major economic/policy/regulation challenges facing the photovoltaics industry moving forward? Bailey says it’s rapid fluctuations. “The industry would be much better served with a less lucrative, steady set of policies and regulations, than those which foster excessive growth too quickly. We have been, and still are, dependent to a large degree on government programs to drive the growth in PV. Unfortunately, government regulation generally also means increased costs in many ways, especially when those programs are not uniform. This is especially apparent in the US where the complexity of policy and economic programs can be staggering and certainly sometimes an obstacle for adoption of solar while at the same time providing one of the underlying economic drivers. It does our new industry no good to complain that all other energy sources have always been more subsidized in reality than solar, although this is quite true. Rather our path to success will continue to be to push for reasonable enabling government support of this remarkable distributed and unlimited energy generation until the economics of solar are overwhelmingly favorable to the market, Bailey said.

Ajeet Rohatgi, Suniva, Georgia Tech

Dr. Ajeet Rohatgi is a Regents' Professor and a Georgia Power Distinguished Professor in the School of Electrical Engineering at the Georgia Institute of Technology (Georgia Tech), where he joined the ECE faculty in 1985. He is the founding director of the University Center of Excellence for Photovoltaic Research and Education (UCEP) at Georgia Tech. Dr. Rohatgi is also the Founder and CTO of Suniva, Inc. a manufacturer high-efficiency, low-cost monocrystalline PV cells, using unique processes and techniques that evolved from his work at UCEP. Dr. Rohatgi continues his research interests in the development of cost and efficiency roadmaps for attaining grid parity with silicon PV, and innovations in cell design and technology.

Under Dr. Rohatgi's leadership, Suniva has accomplished several industry firsts and achievements in manufacturing, technology, research, and development, including the fastest ramp-up to 100MW production in the industry; the raising of $130 million in capital following the formation of Suniva in 2007; the successful production of cell efficiencies exceeding 18%; pilot production of cell efficiencies exceeding 18.5%, and R&D cell efficiencies exceeding 20%. Today, Suniva is the highest cell efficiency producer in the U.S.

Dr. Rohatgi is an IEEE Fellow. He has published more than 370 technical papers in the PV field and has been awarded 11 patents. Dr. Rohatgi has been widely recognized for his research and development contributions:

  • Recipient of the 2010 Outstanding Achievement in Research Innovation Award, nominated on behalf of the faculty of the School of Electrical and Computer Engineering
  • Leadership in Technology award by Renewable Energy World for his achievements in advancing the market for renewable energy in North America, 2010
  • Envention Award by Atlanta Business Chronicle for conservation and pollution-curbing efforts, 2009
  • Hoyt Clarke Hottel Award by the American Solar Energy Society (ASES) award committee for outstanding educator and innovator in the field of photovoltaics, 2009
  • Thought Leadership Award finalist by the Aspen Institute's 2009 Energy & Environment Awards, 2009
  • Climate Protection Award by the U.S. Environmental Protection Agency (EPA) for dedication and technical innovation in PV, 2009
  • One of The Five Most Influential People in Renewable Energy by Power Finance & Risk Magazine, 2008
  • Georgia Institute of Technology Outstanding Research Program Development Award, 2007
  • William Cherry Award by the IEEE Photovoltaic Specialists Conference, 2003
  • Rappaport Award by the U.S. Department of Energy/NREL, 2003
  • Georgia Tech Distinguished Professor Award, 1996
  • As part of the 1996 Olympic Games in Atlanta, Dr. Rohatgi and his team designed and installed the world's largest grid-connected, roof-top PV system on the Georgia Tech Aquatic Center
  • Westinghouse Engineering Achievement Award, 1984

Rohatgi received a B.S. degree in Electrical Engineering from the Indian Institute of Technology, Kanpur, in 1971, and a M.S. degree in Materials Engineering from the Virginia Polytechnic Institute and State University, Blacksburg, VA, in 1973. He received a Ph.D. in Metallurgy and Material Science from Lehigh University, Bethlehem, PA, in 1977. Prior to joining the Electrical Engineering faculty at the Georgia Institute of Technology, Dr. Rohatgi was at the Westinghouse Research and Development Center in Pittsburgh, PA in 1977 and became a Westinghouse Fellow while working on the science and technology of photovoltaic and microelectronic devices.


Daniel Nocera, MIT

Daniel G. Nocera is the The Henry Dreyfus Professor of Energy and Professor of Chemistry at MIT in Cambridge, Mass. He says that solar energy is the only feasible long-term way of meeting the world’s ever-increasing needs for energy, and that storage technology will be the key enabling factor to make sunlight practical as a dominant source of energy. He has focused his research on the development of less-expensive, more-durable materials to use as the electrodes in devices that use electricity to separate the hydrogen and oxygen atoms in water molecules. By doing so, he aims to imitate the process of photosynthesis, by which plants harvest sunlight and convert the energy into chemical form.

Recently, expanding on work published two years ago, Nocera and his associates have found yet another formulation, based on inexpensive and widely available materials, that can efficiently catalyze the splitting of water molecules using electricity. This could ultimately form the basis for new storage systems that would allow buildings to be completely independent and self-sustaining in terms of energy: The systems would use energy from intermittent sources like sunlight or wind to create hydrogen fuel, which could then be used in fuel cells or other devices to produce electricity or transportation fuels as needed.

Nocera pictures small-scale systems in which rooftop solar panels would provide electricity to a home, and any excess would go to an electrolyzer -- a device for splitting water molecules -- to produce hydrogen, which would be stored in tanks. When more energy was needed, the hydrogen would be fed to a fuel cell, where it would combine with oxygen from the air to form water, and generate electricity at the same time.

An electrolyzer uses two different electrodes, one of which releases the oxygen atoms and the other the hydrogen atoms. Although it is the hydrogen that would provide a storable source of energy, it is the oxygen side that is more difficult, so that’s where he and many other research groups have concentrated their efforts. In a paper in Science in 2008, Nocera reported the discovery of a durable and low-cost material for the oxygen-producing electrode based on the element cobalt.

Now, in research being reported in the journal Proceedings of the National Academy of Science (PNAS), Nocera, along with postdoctoral researcher Mircea Dinc? and graduate student Yogesh Surendranath, report the discovery of yet another material that can also efficiently and sustainably function as the oxygen-producing electrode. This time the material is nickel borate, made from materials that are even more abundant and inexpensive than the earlier find.

Even more significantly, Nocera says, the new finding shows that the original compound was not a unique, anomalous material, and suggests that there may be a whole family of such compounds that researchers can study in search of one that has the best combination of characteristics to provide a widespread, long-term energy storage technology.

“Sometimes if you do one thing, and only do it once,” Nocera says, “you don’t know -- is it extraordinary or unusual, or can it be commonplace?” In this case, the new material “keeps all the requirements of being cheap and easy to manufacture” that were found in the cobalt-based electrode, he says, but “with a different metal that’s even cheaper than cobalt.”

But the research is still in an early stage. “This is a door opener,” Nocera says. “Now, we know what works in terms of chemistry. One of the important next things will be to continue to tune the system, to make it go faster and better. This puts us on a fast technological path.” While the two compounds discovered so far work well, he says, he is convinced that as they carry out further research even better compounds will come to light. “I don’t think we’ve found the silver bullet yet,” he says.

Already, as the research has continued, Nocera and his team have increased the rate of production from these catalysts a hundredfold from the level they initially reported two years ago. In addition, while the earlier paper and the new report focus on electrodes on the oxygen-producing side, originally the other electrode, which produced hydrogen, included the use of a relatively expensive platinum catalyst. But in further work, “we have totally gotten rid of the platinum of the hydrogen side,” Nocera says. “That’s no longer a concern for us,” he says, although that part of the research has not yet been formally reported.

The original discovery has already led to the creation of a company, called Sun Catalytix, which aims to commercialize the system in the next two years. And his research program was recently awarded a major grant from the U.S. Department of Energy’s Advanced Research Projects Agency - Energy.

Frank Dimroth, Fraunhofer Institute for Solar Energy Systems ISE

Following his undergraduate degree in Zurich, Frank Dimroth began doctoral studies at the Fraunhofer ISE in the area of experimental physics and received his Ph.D. in 2000 at the University of Constance. Very early on, he was successful in the field of semiconductor epitaxy, and in 2007 he was named manager of the group "III-V Epitaxy and Solar Cells," a group currently with 50 employees. At 39, he is the author of around 120 scholarly articles and the holder of nine patents for photovoltaic cells. He has supervised numerous undergraduate theses and doctoral dissertations in the area of photovoltaics. With Dr. Andreas Bett, department head and deputy director of Fraunhofer ISE, he has been a driving force in the area of highly efficient III-V multiple-junction solar cells and concentrator photovoltaics over the past ten years. In 2005 the two researchers were involved in the establishment of Concentrix Solar GmbH, a spin-off of the Institute. The company produces concentrator photovoltaic systems and has recently installed its first concentrator solar power plant in Spain.

Notably, Dimroth also recently won the “Fondation Louis D” award, the highest-endowed award presented in France for achievements in science, specifically for the metamorphic triple-junction solar cell which has a record efficiency of 41.1%. "I am extremely pleased for my team and the entire Institute in light of this outstanding research prize and the international recognition it brings for our work," Frank Dimroth stated. "This prize shows us once again that we are on the right track toward developing solar technologies. Concentrator systems have the potential to supply Southern Europe with low-cost solar electricity in a matter of just a few years. With our work we are tackling an important task for the future."
A multi-junction solar cell is created with the aid of processes similar to those used in the semiconductor industry. "Our work involves a modern epitaxial process known as metal organic vapour phase epitaxy," Dr. Dimroth explained. The process involves successively depositing solar sub-cells on top of each other on a substrate of germanium. The result is a wafer-thin solar cell structure just a few µm thick, with a well-hidden complex inner structure of up to 50 monocrystalline layers. With the development of metamorphic crystal growth, Frank Dimroth and his colleagues have made it possible to use a larger range of III-V compound semiconductors to grow multi-junction solar cells. This makes the solar cells better adapted to the spectrum of wavelengths found in sunlight.
To date, multi-junction solar cells have been used in space technology to supply satellites with energy. To tap into the high potential efficiencies for regenerative power generation here on earth, Frank Dimroth and his colleagues came up with a special design: They developed a photovoltaic concentrator module that uses Fresnel lenses to concentrate solar radiation by a factor of 500 onto triple-junction solar cells only 3 mm2 in area. This reduces the costly semiconductor surface area required and makes III-V multi-junction solar cells for electricity generation an attractive alternative in regions rich in direct sunlight. Prof. Eicke R. Weber, Director of Fraunhofer ISE, is convinced: "We expect that high-efficiency concentrator technology - in addition to photovoltaics using crystalline silicon and the classic thin-layer technology - will become established as a third technology for cost-efficient generation of solar electricity in the sunny regions of the world."

When asked to describe the major trends in the photovoltaics/solar power industry today, Dimroth said it was a difficult question to answer. “I am not even sure if there is one major trend in the PV industry except for the unbroken strategy to grow fast and to prove that PV can cover a substantial part of our energy need,” he said. “Cost reduction by further integration, scaling and growth is still the main driver in this industry. A movement towards utility scale installations in the MW power range is certainly a trend which can be observed. With the major drop in PV system prices over the last years, competition has been growing in most of the market segments putting pressure on innovation and cost-efficient production. Asia has certainly gained market share in this process. Technological advancement may become a more important driver in coming years,” Dimroth said.

Dimroth went on to say that, today, we do have a very good understanding of what is needed to convert solar radiation into electricity. “The physics of solar cells are well understood and it is unlikely that a new technology will change our picture completely. Semiconductors have been proven to be most efficient in this conversion process and silicon PV is clearly the dominating material today. Thin film PV is gaining market share and technologies like concentrating photovoltaics are currently introduced in small volumes. There are advantages of each solar technology in a specific market segment and we will certainly see a diversity of these technologies for roof-top, building integration, power plants, combined heat and power, consumer electronics and the many other markets which are developing out of this industry. It is a question of engineering to optimize a solar cell and PV system for a specific application and make sure that it can meet the targets. There are different challenges associated to each technology but it is mainly a question of the R&D effort to solve them. The good thing about photovoltaics is that there are no unsolved technological barriers like for nuclear fusion. But there is still a lot to learn and develop and the access to resources in sufficient quantities and at low cost will certainly remain a continuous challenge as long as the industry is growing fast,” he said.

What about major economic/policy/regulation challenges facing the photovoltaics industry? “For keeping the strong growth rates of the PV industry over the coming years, the market has to diversify. Germany will unlikely remain the strongest motor of the PV industry for another decade. We have to convince governments, the public and utilities that investing and building up capacity in solar energy is not a waste of money but the most promising long-term solution to our energy supply situation and a responsibility for our generation. This requires political actions like feed-in tariffs, large volume investments, financing structures, financial security as well as a strategy to implement large amounts of electricity from renewable sources into the grid. We need to continuously address these questions and talk to decision makers throughout the chain to make sure that PV can become a substantial energy technology in the future,” he said.


Hans Werner Schock, Helmholtz Institute, Berlin

Hans-Werner Schock, born in 1946 in Tuttlingen, Germany, studied electrical engineering at University of Stuttgart and earned his doctorate at the Institute of Physical Electronics, where he later became scientific project leader of the research group “Polycrystalline Thin-Film Solar Cells”. Since 2004, he has worked at HZB as department head of the Institute for Technology. He is author and co-author of more than 300 publications and has submitted and been involved in more than ten patents in the field of solar energy technology.

He was nominated for his “insights in chalcopyrite materials for solar cells, his perseverance also when PV interest was at all-time lows, his role in making CIS and CIGS viable PV materials (especially through the Euro-CIS breakthrough in the early 90s, his remarkable combination of device and material and general technology knowledge and ideas, make him the central figure in the coming of age of CIGS as a serious thin film solar cell option. His work laid the basis for many a company that is now pursuing CIGS technologies and did so on a global scale.”

Schock recently received the “Becquerel Prize” following his plenary lecture on “The Status and Advancement of CIS and Related Solar Cells”. The first pioneer tests on chalcopyrite-based solar cells took place under his direction as early as 1980, and were to make solar energy more efficient and more competitive.

At present, Hans-Werner Schock’s group is researching new material combinations of abundant, environmentally friendly chemical elements and is continuing to refine solar cells based on these materials. The solar cells developed at HZB under Hans-Werner Schock’s leadership hold several efficiency records: CIS cells in the high-voltage range (12.8%), flexible cells made from plastics (15.9%) and conventional CIGSe cells (19.4%). The aim is for “solar cells to be integrated into buildings, for example, no longer as an investment, but as a matter of course,” says Schock.

The “Becquerel Prize” was first awarded in 1989 on the occasion of the 150th anniversary of Becquerel’s classic experiment on the description of the photovoltaic effect. With it, French physicist Alexandre Edmond Becquerel laid the foundation for the use of photovoltaics.

Ely Sachs, 1366 Technologies, Inc.

Emanuel “Ely” Sachs is the Chief Technical officer of 1366 Technologies Inc, a company he founded together with Frank van Mierlo. The goal of 1366 is to make silicon solar cells cost competitive with coal generated electricity.

Ely Sachs is also a Professor at MIT, specifically the Fred Fort Flowers and Daniel Fort Flowers Professor of Mechanical Engineering at MIT. Dr. Sachs is totally focused on PV for his research and he supervises a growing PV research group at MIT. The group is currently pursuing projects in wafer fabrication, surface texturing for light trapping, metallization, and light trapping at the module design level. He also aims to drastically reduce the cost of wafer manufacturing through a new groundbreaking kerfless wafering technology called Direct Wafering.

Sachs is the inventor of "String Ribbon," a ribbon crystal growth process for making low cost substrates for solar cells, which is now being commercialized by Evergreen Solar, Inc. of Marlboro, MA.

Sachs co-invented Three Dimensional Printing, a manufacturing process for the creation of 3D parts directly from a computer model in layers. 3D Printing is being commercialized in fields-of-use including appearance models, ceramic molds for castings, direct metal tooling, end-use metal parts, medical devices, and pharmaceuticals.

Sachs is also known for work in the area of Process Control of VLSI fabrication and is a co-inventor of a plasma etch diagnostic tool now commercially available.

Sachs is the author or co-author of more than 110 technical papers and is the inventor or co-inventor of more than 40 patents. Sachs was a Hertz Foundation Fellow and earned the Hertz Foundation Doctoral Thesis Prize in 1983 for his work on String Ribbon.

Rajendra Singh, Clemson University

Rajendra Singh is the D. Houser Banks Professor & Director, Center for Silicon Nanoelectronics, Holcombe Department of Electrical and Computer Engineering, at Clemson University in Clemson, SC. He said he remembers back to 1973 during the days of oil embargoes when he decided to do his PhD thesis on Solar Cells. “The vision I had in 1980 is happening only now, 30 years later,” he said. “The economic crisis of 2008, followed by recession or low economic growth in developed economies and high growth in emerging economies, has changed the landscape of energy business all over the world,” he noted. That motivated him to write a book, titled “Sustainable Energy for for Sustained Growth of Developed and Developing Economies.”

In his, Singh says he has examined “every energy source and other than free fuel based PV and wind there is no other solution. Due to inherent advantages, PV will take over wind and eventually we will have PV as the dominant electricity generation technology. In our lab, we are also working on solving electrical energy storage problem by the use of solid state capacitors based on giant dielectric constant materials. Once we have the solution of electrical storage problem, virtual vertical integration of the entire PV industry coupled with co-location of all component manufacturers and ultra large scale PV manufacturing (Giga watt and higher scale) in a single location, PV generated power will be cheaper than any other energy conversion technology. Thus the day is not too for when PV as a solid state device will play the same role what CMOS has done for the world of today that is based on global economy,” he said.

The major trends Singh sees today is that the PV industry will continue to grab more and more share of electricity generation throughout the world. “Large scale solar farms will continue to dominate the PV electricity generation and roof top PV will be only in the range of 25-30%,” he said.

Singh said the most difficult technical challenge is to solve the electrical storage problem. “Once we have solved the problem of electrical storage (cost less than $0.25 per watt), ultra large scale PV manufacturing and virtual vertical integration of PV industry can provide installed PV systems (~minimum 5-10 MW systems) cost of about $2 to $2.50 per watt. At this price in addition to the market of developed economies, there is a huge market of some 2.5 billion people who are forced to rely on biomass -- fuel wood, charcoal and animal dung -- to meet their energy needs for cooking. Providing clean energies to these 2.5 billion people by PV will create a market that will make PV industry as big as electronics industry (~$1.5 trillion per year),” he said.

The major economic/policy/regulation challenges facing the photovoltaics industry moving forward? “The challenges are different for developed and emerging economies,” Singh noted. “For developed economies the driving force is the job creation, energy security and reduction of carbon emission. For emerging economies (China and India particularly) providing energy to meet the goal of 8-9 % growth per year is the main issue. Throughout the world, financing PV projects is the most difficult problem. Nuclear energy is not economical for any country and no more new nuclear reactors should be constructed. However, in many parts of the world nuclear is still being considered as an option for future generation of electricity. Due to the policies supported by various governments, investors do not see the role of PV (free and clean fuel) as it should be in the 21st century. Current financing mechanisms are inadequate to bring large sum of money in PV business. Policies need to be created for flow of large capital in PV industry. Utilities should be forced (by legislation) to use more and more PV (on an incremental basis) and the value of peak power generation must be recognized throughout the world,” he said.

Dan Arvizu, NREL

Dr. Dan Arvizu has been the director and chief executive of the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) since January 15, 2005. NREL, in Golden, Colorado, began operations in 1977 and is the DOE's primary laboratory for energy efficiency and renewable energy research and development. NREL is operated for DOE by the Alliance for Sustainable Energy, LLC (Alliance). Dr. Arvizu is President of the Alliance and also is an Executive Vice President with the Midwest Research Institute, headquartered in Kansas City, Missouri.

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After more than three decades of professional engagement in the clean energy field, Dr. Arvizu has become one of the world's leading experts on renewable energy and sustainable energy. In the past three years, he has testified before Congress four times, given state-of-technology presentations at three Congressional caucus briefings, and keynoted 12 major national and international conferences. As NREL's Director, he has established and implemented a new institutional strategy to position the lab for higher impact and contributions to national energy challenges. In the past three years, he has overseen an increase of more than 50% in the lab's operating budget and has helped attract over $400M for new infrastructure.
In 2004, Dr. Arvizu was appointed by President Bush for a six-year term to serve on the National Science Board, which is the governing board of the National Science Foundation and the national science policy advisory body to the President and Congress. He chairs the Audit and Oversight Committee and is the co-chair of the task force on "Building a Sustainable Energy Future: U.S. Actions for an Effective Energy Economy Transformation."

Arvizu serves on a number of boards, panels and advisory committees including:

  • American Council on Renewable Energy Advisory Board
  • Energy Research, Development, and Deployment Policy Project Advisory Committee at the Harvard Kennedy School
  • Singapore Clean Energy International Advisory Panel
  • Hispanic Engineer National Achievement Award Corporation
  • Colorado Renewable Energy Authority Board of Directors
  • Intergovernmental Panel on Climate Change Working Group III -- where he is currently serving as a coordinating lead author on a special report on renewable energy.

Prior to joining NREL, Dr. Arvizu was the chief technology officer with CH2M HILL Companies, Ltd. Before joining CH2M he was an executive with Sandia National Laboratories in Albuquerque, New Mexico. He started his career and spent four years at the AT&T Bell Telephone Laboratories.


Martin Green, University of New South Wales

Martin Green (born 1948) is an Australian professor at the University of New South Wales (UNSW), where he is focused on the development of solar energy. He was born in Brisbane and was educated at the selective Brisbane State High School, graduated from University of Queensland and completed his PhD on a Commonwealth Scholarship at McMaster University in Canada, where he specialized in solar energy. In 1974, at the University of New South Wales, he initiated the Solar Photovoltaics Group which soon worked on the development of silicon solar cells. The group had their success in the early 80s through producing a 20% efficient silicon cell, which now has been improved to 25%. e has published several books on solar cells both for popular science and deep research, and has been recognized with different awards. He also serves on the Board of the Sydney-based Pacific Solar Pty Ltd. (now known as CSG Solar), as Research Director.

Among the major awards won by Green: Pawsey Medal (Australian Academy); Award for Outstanding Achievement in Energy Research; IEEE Cherry Award; CSIRO External Medal; IEEE Ebers Award; Australia Prize (1999); Gold Medal from the Spanish Engineering Academy; Medal of Engineering Excellence for Distinguished Achievement in the Service of Humanity from the World Engineering Federation (Hannover, 2000); Millennium Award from the World Renewable Congress; Right Livelihood Award; Karl Böer Solar Energy Medal of Merit Award from the University of Delaware; Finalist, European Inventor of the Year (together with Stuart Wenham); Winner, 2008 Scientist of the Year Award; 2009 Zayed Future Energy Prize finalist.

Arvind Chel, Energy Forum

Dr. Arvind Chel is the president of the Energy Forum and a Senior Research Scholar at the Centre for Energy Studies in New Delhi, India. The major trend that he observes is that the PV industry is growing rapidly in both ceveloped and developing countries. “Developed countries had already setup grid connected PV systems since the cost of electricity in developed countries is much higher compared to developing countries like in India due to subsidy on coal based power generation,” Chel said. Solar electricity prices are today around 30 cents/kWh, which is 2-5 times the average of residential electricity tariffs in developed countries. “Through the Jawaharlal Nehru National Solar Mission in India, solar photovoltaic stand alone systems are going to be installed in large scale all over the part of India. Water pumping, solar street lights are becoming popular in many places in India both in government as well as the private sector. Cost of PV system has come down to 4.17 dollar/Wp or 4.11 Euro/Wp in August 2010 as compared to 27 dollar/Wp in 1982. The PV module cost is around 50 - 60% of the total installed cost of a solar PV system. Therefore the solar module price is the key element in the total price of an installed solar PV system. All prices are exclusive of sales tax depending on the country or region can add 8-20% to the prices, with generally highest sales tax rates in Europe,” he said.
Chel says that, currently, BIPV systems have received wide attention from SolarFrameWorks BIPV CoolPly system install at New England Patriot Place. The BIPV CoolPly system simultaneously cools the roof and cools the solar modules in the summer. In the winter, the system provides additional insulation preventing heat loss while optimizing power production to promote optimal power production and energy conservation in commercial buildings.

Training and human resource development is another challenge for PV industry. Formulation of PV module standards considering the life time problems and quality output issue with age of PV modules.
The opportunity for photovoltaics is to identify a technology that eliminates the cost, product and manufacturing challenges of existing inorganic approaches - while creating new capabilities. Current inorganic materials have challenges including:

  • Difficult and expensive to manufacture
  • Limited substrate options - heavy glass or stainless steel
  • Limited basic materials - some environmentally unfriendly like Cadmium
  • Limited aesthetic options - black or blue only
  • Heavy and cumbersome "picture frame" support elements
  • Extremely fragile.

The major economic/policy/regulation challenges facing the photovoltaics industry moving forward? “Sales tax depending on the country or region can add 8-20% to the prices of PV modules which is highest in Europe can act as barrier for PV technology penetration. New subsidization regulations can make this industry sustain its market demand. The interplay between incentives and policy support on the hand and technology cost point reductions through industry innovations and scale will determine how PV industry grow in developing countries like India,” he said.

Chel says it’s also necessary to create policy for street lighting and water pumping in agricultural areas to increase the penetration of PV industry. “Various application both grid and off grid applications of PV system need to be explored and given incentives for operation for example mobile tower in remote villages in India are now powered by solar PV replacing diesel generators there by reducing environmental pollution,” he said.


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Volume 18, Issue 3


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