Archives for the month of: October, 2012

Very interesting year for PV around the world. The ‘solar rush’, led by numerous support policies enacted in the second half of the 2000s decade, by the spectacular entry of China on the world market, and by a drive to produce ‘green jobs’ to revitalize the ailing manufacturing sector of several industrialized countries, has gone a little too fast for some markets. As is usually the case for rapidly expanding industries, it appears it is now time for a serious restructuring. Several large players have already gone belly-up. The PV industry, it seems, will look quite different in a few months from what it was at the beginning of 2012. The question is, of course, what will happen to the drive for PV installations as governments pull back support.

Germany, the hailed dean of renewable electricity expansion, has not escaped these developments, far from it. With an astonishing 28GW of installed capacity for PV electricity generation, Germany is also dealing with important changes in its own industry but also in its policy support. In June 2012, after three months of harsh debates on modifications to the EEG (the major piece of legislation supporting PV and other renewables), the German Parliament has adopted amendments that will affect not only PV deployment rates, but also the very way that PV is deployed across the country. Now that panel prices have dropped to a small fraction of what they were 5 years ago, and now that electricity generation from renewables (including PV) presents costs that are at parity with electricity retail rates in several regions, the German government is trying to shift gears. We are now at a junction, where PV deployment has ceased to be so hard and expensive that we do ‘whatever we can’ to pursue it. The Germans are now attempting to modify how developers and other actors see and think about PV electricity, not as a promising niche industry but as a full-fledged component of electricity markets.

These changes are intended to produce a different type of planning for PV installations, where developers are encouraged to seek means other than FIT support, and to think carefully about electricity markets when choosing where to site their projects. This is the step that comes logically after a successful FIT program. It will be fascinating to see how that market, which has shown in the past few years how impressively quickly it can change and adapt, deals with these new times. A short-term future that looks promising, and definitely interesting, as I said at the beginning. Stay tuned!

Yours truly,

Simon Langlois-Bertrand

PhD Candidate, Norman Paterson School of International Affairs, Carleton University

Hello everyone! I’m here to tell you all about my trip to Frankfurt, Germany for the 27th European Photovoltaic Solar Energy Conference and Exhibition!  I flew out of Toronto at 1pm on Saturday afternoon, and I landed in Germany at 6am Sunday morning; that’s 12am Toronto time. This was my first time travelling alone, so I was admittedly nervous about the whole experience. Flying alone into a foreign country where I don’t speak the language, and where I can’t read street signs, made the prospect of navigating my own way from the airport to my hotel a rather daunting task, but I made it okay!  At the hotel, I met up with the other members of the Photovoltaic Innovation Network (PVIN), and we set out to explore the city before our week-long conference. Frankfurt is one of the financial hubs of Europe, and it features hundreds of different banks from all over the world. It is a very international city, but also a very quiet one. At night, you don’t see too many people walking in the streets; living in Hamilton, and having spent time in Toronto, this is not something to which I am accustomed!

Frankfurt, being such an international city, made an appropriate setting for the conference. 4024 people from across 76 countries participated either by giving talks, presenting posters, or simply listening to the presentations. The conference brought a lot of different people together, and with them came a lot of different ideas. During the first few days, the presentations focused on solar cell devices, and I must say that the diversity of solar cell designs is quite amazing. There were talks on traditional silicon cells, organic cells, heterojunction cells, multijunction cells, Dye and Hybrid cells, concentrator systems and so much more! My own work involves silicon, so I was particularly interested in these talks. Silicon has been around for a long time in photovoltaics, and it is a very mature technology. I observed that a lot of the current interest in silicon is not about improving devices, but about finding ways of making them cheaper while maintaining the same performance.  For example, there were many talks on replacing the silver in silicon cells with cheaper metals such as nickel and copper. While silver has nice electrical properties that make it attractive for use in solar cells, it is also expensive and the price is somewhat unpredictable.

Later into the week, the presentations focused on the ‘big picture’ issues of solar energy. There were talks on large-scale photovoltaic power plants, grid integration, manufacturing and processing, and solar cell markets, just to name a few. These talks were interesting because they covered issues that we don’t often think about at the research level. For one, we often don’t consider the manufacturability of the devices we make in the lab. It is one thing to be able to make high efficiency solar cells one at a time in a laboratory, but it is quite another to be able to produce them in higher quantities at a large-scale factory. As a researcher, the talks I saw later in the week really put things in perspective. I saw that solar energy is not just about the research; research is only the first link in a long chain. Included in the chain are the manufacturers that mass produce cells, the engineers who build and install the systems, and the policy makers that study and regulate the deployment of these systems. There are so many contributors from across numerous disciplines working in solar energy, and the conference really reinforced that idea in me.

I must say that my favourite presentations were those by Dr. Harry Atwater from the California Institute of Technology, and Dr. Martin Green from the University of New South Wales. Both men are very prominent researchers in the field of photovoltaics, and each lead a large group of graduate students and post docs that work at the frontier of photovoltaic research. Dr. Green in particular has done some of the pioneering work in silicon cells, including making a cell that is 25% efficient. This cell holds the world record for efficiency! A neat little bit of trivia is that Dr. Green graduated with a PhD from McMaster University, where I did my undergrad and am currently working on my Master’s degree. The talks given by Drs. Atwater and Green focused on the exciting work being done to incorporate the field of plasmonics into photovoltaics. Plasmonics is a field that deals with the interaction of light with nano-sized metal structures, and the strange phenomena that can result. For example, thin sheets of metal with nanoscopic holes can be made to transmit light in one direction, but not in the opposite. For a solar cell, this means that light could enter a cell, but not escape it. A useful application, indeed!  As solar cells are made thinner, in a push to reduce cost and the amount of material used, their ability to capture light is compromised. Techniques for manipulating and trapping light then become necessary in order to maintain comparable performance with thicker cells. The field of plasmonics happens to be brimming with these techniques. I should mention that my own research involves plasmonics. I am working with ultra-thin silicon cells, and using nano-sized particles of silver as a scheme for light trapping. This is why I was especially interested in these talks. Seeing Drs. Atwater and Green speak at the conference was truly a pleasure! Considering that they are co-authors on many of the research journals that I read, it felt like I was at a concert seeing my favourite musician play!

Plasmonic nanoparticles.

 

Alongside the conference there was a solar energy exhibition, in which companies and research institutes ran booths that showed off what each had to offer. Obviously there were many companies offering just solar panels, and some had put a decorative spin on their design. For example, I saw one company that had designed the cell to have a waterfall trickling down it! Definitely something that would look nice in a backyard! Other companies were offering equipment for research or manufacturing, and these booths were the most prominent at the exhibition. The most impressive booth, in my opinion, was from a company that had actually brought a solar cell assembly line into the building. There were periodic demonstrations in which cells would be produced, ready to be used in a panel. The operators were quite secretive about the assembly line, and photography was prohibited. Our own NSERC Photovoltaic Innovation Network (http://www.pvinnovation.ca) also had a booth at the exhibition, which displayed posters that highlighted the research that we do, and the Universities and companies that are involved. Manning the booth was one of my favourite parts of the trip. At the booth, we (representatives of the Network) were able to talk one-on-one with so many interesting people, and teach them a little about what we do in Canada, and what we have to offer. We talked with students, with members of industry, and other researchers that were interested in our work. The PVIN was (to my knowledge) the only Canadian presence at the conference. I felt truly honoured to be standing there at an international convention, representing our entire country and the research that we do, all while piquing the interest of experts from all over the world. It was an absolutely amazing experience. Being there in person also showed me that interest in solar energy is a truly global phenomenon. It’s really no surprise though; the sun is essentially an unlimited source of energy!

Overall, my trip to Germany was a fantastic experience. I learned a lot at the conference, talked with many interesting people, and made some new friends with other members of the Network. I was very grateful that we all stayed in the same hotel together. Very few people had a working cell phone, so organizing trips for dinner or walks around the city would have been a nightmare had we not stayed under the same roof. The city of Frankfurt was a neat place, and according to the locals, very boring! It was mostly banks and retail stores, but we always found something to do and were never bored. Aside from the conference, food was the highlight of the trip! I don’t think I will ever be able to eat schnitzel again, because it would just pale in comparison to authentic German schnitzel. Although the trip was fun, it was also exhausting, and after a week of being away, I was excited to get home. As I mentioned before, this was my first time travelling by myself and I learned a very valuable lesson: indirect flights are no fun! I flew from Frankfurt to New Jersey, and then I had to get a taxi to New York, where I could fly back to Toronto. After 19 hours of travelling and waiting and four airports later, I finally arrived home safe and sound at Pearson! I will definitely choose my flights more wisely in the future!

Suffice to say, I really enjoyed Germany and the conference, and can’t wait for the next one! Before I go, I’d like to thank Jennifer and Sandra for all of their help in organizing the trip and making it possible! Dankeschön!

-Kevin Boyd (Year 1 of M.A.Sc in Engineering
Physics at McMaster University, Hamilton Ontario)

Scanning electron microscope image of endview of Solar3D prototype

Solar3D Inc, a small research company founded in 2010, has recently fabricated a working prototype of a three-dimensional (3D) silicon solar cell [1]. Conventional solar cells employ a 2D geometry for capturing light. That is, light enters the cell through a 2D plane and is absorbed inside. A 3D solar cell uses 3D structures (the ridge-like structures pictured above) to capture light. An obvious advantage of this geometry is that there is a greater surface area for light absorption, and thus more light can enter a cell. The concept of a 3D cell is not new; cells that use thin nanowire structures to capture light have been known and studied for some time now. However, to the author’s knowledge, Solar 3D’s cell is the first of its kind to employ the ridge-like structures pictured above. Solar3D claims that their cell design offers many advantages over conventional 2D cells [2].

Firstly, conventional cells suffer from unavoidable reflection losses. Techniques exist to reduce these losses, but inevitably some light is always reflected away. A 3D cell is not immune to these losses either, however by virtue of the ridge-structures in such a cell, reflected light may be bounced back and forth between adjacent ridges, increasing the chances of it being absorbed. As well many 2D cells have metal contacts on the front to harvest the electrical current created by sunlight; these contacts are not transparent, so they block some of the sunlight from reaching the cell. In Solar 3D’s cell, the metal contacts run below the light-capturing ridges so that light-absorption is not compromised.

Another advantage offered by Solar 3D’s cell are thin absorbing regions. In a conventional silicon cell, the cell is made relatively thick to promote light-absorption. However, if a cell is too thick the electrons generated by sunlight may not make it out of the cell before being reabsorbed. Solar 3D’s cell overcomes this by using many thin absorbing regions. The thinness allows electrons to be efficiently collected, and the fact that there are many of these regions allows light to be efficiently absorbed.

Finally, Solar3D claims their cell has superior light-collection throughout the day (pictured above). Conventional cells operate most efficiently when the sun is directly overhead. This means that these cells will only perform optimally for a small part of the day. Many solar cell installations mount cells on trackers so that they can follow the sun throughout the day and overcome this disadvantage. According to Solar3D, their cell can collect light effectively over a range of angles, obviating the need for tracking systems, and allowing their cells to operate efficiently throughout most of the day.

The company fabricated their cell in July, 2012 and so far have not released any concrete details about the prototype’s performance. According to Solar 3D’s Director of Technology, Dr. Changwan Son, “When measured relative to a conventional solar cell design, our working prototype produces electricity beyond our previous expectations. First, we fabricated our working prototype. Then we created a simple cell based on the conventional design, using the same fabrication environment, to serve as a control sample. By measuring the side-by-side power output of both cells, we were able to determine the relative performance under a number of conditions, ranging from bright sunlight to lower, diffuse light. In each test, our 3D Solar Cell consistently outperformed the control cell and produced at least 2½ times the amount of electricity under the same conditions.” Unfortunately, the company does not provide any information on what particular “conventional solar cell design” they are comparing their 3D cell to. In the context of silicon, a “conventional cell” can refer to a myriad of devices covering a broad range of performance, and so these claims are rather ambiguous. The company has stated that simulations they have run on their cell design show that it should have an efficiency of 25.47%. This is a rather ambitious claim, considering that the record efficiency achieved in practice for a silicon cell is 24.7% [3]. The top 10 commercially available silicon cells have efficiencies ranging from 19.1%-22.5% [4]. Solar3D has not yet quoted an efficiency for their working prototype.

According to Dr. Son, Solar 3D’s next step is to improve the fabrication process so that they can drive down the cost of manufacturing their 3D devices. Son says “We believe that the result will be a 50% reduction in the cost of solar electricity. Perhaps the installed system cost savings will be even greater.” Again, this is a rather ambitious claim, considering how remarkable a 50% reduction of cost would be for solar energy. Solar 3D’s cell is certainly an interesting design, and the purported advantages it offers (mentioned above) are quite plausible. However, until the company releases detailed performance characteristics for their device, it is difficult not to remain skeptical regarding the company’s more ambitious claims.

-Kevin Boyd (Year 1 of M.A.Sc in Engineering Physics at McMaster University)

 

 

References

[1]. http://www.pv-tech.org/news/solar3d_reveals_working_prototype_of_3d_silicon_solar_cell

[2]. http://www.solar3d.com/technology.php

[3]. http://www.sciencedaily.com/releases/2008/10/081023100536.htm

[4]. http://www.renewableenergyworld.com/rea/news/article/2012/03/sunpower-tops-in-mono-c-si-solar-cell-efficiency

Just came back from Frankfurt, tired from the 10 hour intercontinental flight, but I’m ready to sum up my seven days experience in Germany at the European Photovoltaic Solar Energy Conference (EUPVSEC). The conference closed on Friday, 28th September, after five days of constant reports of research frontiers in all solar energy related fields. Researchers and businessmen from all over the world came to report, summarize, and discuss new findings, innovative ideas, and developments in the field. As a graduate student just beginning to explore this burgeoning business there was much to learn.

As part of Project 2 of the NSERC Photovoltaic Innovation Network (www.pvinnovation.ca), my research aims at improving the lifetime of organic photovoltaics (OPV) while maintaining moderate power conversion efficiency. So naturally I was interested more in the OPV sessions than other topics. It seemed that almost all OPV-related talks were given by industrial researchers and people from companies, a good sign that OPV is no longer solely an academic research interest. There is a strong debate as to whether OPV will ever become commercialized on a large scale but I firmly believe that OPV has a bright future. I think the presentations at the OPV session have proved I am right. Three years ago, people would get excited if they had achieved efficiencies around 6% with OPVs, but now companies present over 10% efficiency of single junction cells with alleged 10 years lifetime. Solliance (http://www.solliance.eu/) demonstrated transparent OPV glass at the conference and their exhibition booth, which is an example of the versatility of organic photovoltaics.

In the future, even if OPVs cannot compete with inorganic solar cells in terms of efficiency, they can still find roles in small scale energy productions such as household power supply or photovoltaic chargers for portable electronic devices. However, this is not the reason why companies are willing to invest their money on OPV. Their hope is that OPV will finally win over inorganic photovoltaics by the low price and ease of production. Several companies have proved the feasibility of roll-to-roll printing of organic photovoltaic films. With this technique, solar cells can be produced like printing newspapers. Professor Yang Yang from UCLA, one of the pioneer researchers in the OPV field, encouraged OPV people at his plenary talk by sharing his experiences on organic light emitting diode (OLED) developments. The pure research topic at the time of the early 90s has become real product available in stores now. Interestingly, the large screen at the airport terminal was repeatedly broadcasting LG’s commercial of their new OLED TV while I was waiting to board my flight. One may very well expect the same story happening to OPV ten years later.

On Friday, a fellow Network student and I went to check out the Max-Plank Institute for Polymer Research at Mainz (http://www.mpip-mainz.mpg.de//groups/muellen). One of my impressions about this institute is that all the equipment everything is in large scale. With such abundant facilities and funding, no wonder hundreds of high quality articles are being published each year in this three floor building, under the supervisions of only six directors.

Frankfurt is not only the financial capital but also a beautiful and historical city with tons of interesting places to explore. Somewhat more than in North America, I can strongly feel the history and culture while I was walking in the city. I was amazed by the size of the cathedrals, the number of museums, and the convenience of public transit system. Unfortunately, I wasn’t able to see the entire city within a week. If you plan to go to Frankfurt for pleasure, I highly recommend the Frankfurt Card. With this card, which costs you only 13.5 Euros for two days validity, you get public transit rides, half off on tickets to all city owned museums and it’s only eight Euros for a whole day bike rental. In all, I had a wonderful experience at the conference and in the city, thanks to the Network for offering me this opportunity; I wish my visa was valid for a longer period of time.

-(Ben) Chi Zhang (Chemistry MSc., Year 3 at Simon Fraser University)

See Ben’s Photojournal at: http://www.pvinnovation.ca/files/Photo_Journal_Ben_Zhang.pdf