Archives for the month of: January, 2013

At CanSIA Solar Canada in Toronto I attended a breakout session that focused on developing grid technologies for the integration of solar PV and other renewables. The speakers covered a broad range of topics, including weather forecasting for solar load balancing (Rhonda Wright-Hilbig, IESO), economic modelling of renewable penetration (Justin Malecki, Clearsky Advisors), and PV-pilot projects in isolated communities (PJ Fernandex, ABB and Scott Henneberry, Schneider Electric).

Rhonda Wright-Hilbig started off by discussing how the Independent Electricity System Operator (IESO) sees the Ontario grid evolving over the next few years and how they will meet the challenges created by these changes. Of note, they expect the complete retirement of coal powered electricity by 2015, with the Ontario Power Generation shutting down three coal fired plants last year alone. To compensate for the loss in generation capacity nuclear, hydro, natural gas and solar are seeing increased deployment, with the expectation that Ontario will hit 3 GW of solar PV generation, out of 20-24 GW for the entire grid, by 2018.

Solar PV generation has some unique characteristics, such as variability in output from weather and seasonal cycles, which must be characterized to ensure the smooth operation of the grid. During the talk Ms. Wright-Hilbig emphasized that each generation technology has a particular set of characteristics that must be accounted for, for successful grid integration. In this sense, solar PV is no different than any other generation technology. However, solar and wind generation are unique in their sensitivity to meteorological conditions. In response IESO has developed a Centralized Forecasting Service (www.ieso.ca/centralized.forecasting) that all renewable projects with greater than 5 MW generation are required to participate in. This services allows IESO to anticipate changes in renewable generation and respond accordingly.

Grid storage is another method to smooth out variability in renewables. As such, storage technologies are expected to play an increasing role in Ontario’s and Canada’s grid. However, at this early stage, making accurate predictions about the rate of deployment is difficult. Justin Malecki from Clearsky Advisors sees 100-1000 MW of grid storage deployed across Canada over the next decade. In part, these numbers will depend on the rate of renewable generation deployment across the nation, which leads to the wide-margin of error in these forecasts.

Both forecasting services and storage allow for active and passive management of the renewable energy supply. Few specifics were offered for demand-side management, as these technologies have yet to be made widely available. However, several of the speakers emphasized the important of demand-side management technologies. Scott Hanneberry firmly stated this point by claiming that the most efficient storage is a flexible load. IESO expects to start seeing smart-appliances like hot water heaters, electric vehicles, and other home automation technologies across Ontario in the future. All of these technologies will help them manage peak demand more effectively and shift loads to low-demand time during the night.

Overall, it was clear that the global industry is climbing the learning curve for a high-penetration of renewables on the grid. In Canada and Ontario the investments are being made today to facilitate significant renewable deployment in the coming years.

Josh LaForge

Joshua LaForge

PhD Candidate in Electrical and Computer Engineering Department

University of Alberta

 


Hello everyone! I was recently in Toronto attending Solar Canada 2012, a conference on the Canadian solar industry. The conference was put on by CanSIA “a national trade association that represents approximately 650 solar energy companies throughout Canada”. The conference featured panels of industry leaders discussing issues such as policy, market trends, and the future of the solar energy in Canada. I will be giving a brief summary of one of the talks I attended, which highlighted the current state of the solar industry. Panelists included Mike Crawley, President of International Power Canada, Doug Urban, Managing Director of Hanwha Solar Canada Inc. ,Mike Dilworth, Vice President and Country Manager of SunEdison Canada, Kerry Adler, Director, President and Chief Executive Officer, of SkyPower Global and Terry Olynyk, Director of Renewable Energy, PCL Constructors. Their discussion covered what the solar industry looks like in Ontario today, the issues that it is currently facing, both financially and politically, as well as what the future holds.

One of the most pressing issues that was brought up was the high level of uncertainty in Ontario’s solar energy market. Uncertainty scares away investors, and as a result less green-energy jobs are created, and the development of solar power slows.  Canadian solar manufacturers are currently on the lookout for the recent ruling from the World Trade Organization (WTO), which claims that Ontario’s Feed-in-Tariff (FIT) program, part of the Green Energy Act, violates international trade law “by unfairly pressuring producers of clean energy to buy hardware and services from companies located in the province.” [1]. To give a bit of an overview, the Green Energy Act stipulates that in order for a solar power producer to qualify for Ontario’s FIT program, 60% of the installation must be produced by Canadian manufacturers (this is the domestic content clause of the Act)[2]. This promotes the development of a solar manufacturing industry in Ontario.  The WTO ruling challenges this part of the Act. Ontario solar manufacturers fear that if Ontario complies with the WTO and removes the domestic content requirements from the FIT program, then they will not be able to compete with foreign manufacturers. Without the FIT program, and without the requirement for Canadian produced content, manufacturers would go out of business. This leads into another point of uncertainty, and that is the government’s stance on green energy. There is possibility of an election coming up next year, and in the previous election opposition leader Tim Hudak said that he would abolish the Green Energy Act entirely. Even without a change in government, the Liberal leader Dalton McGuinty is leaving office soon, and there is a strong possibility that his successor will have a different approach to green energy.  All in all, the level of uncertainty in the Ontario market makes investment quite risky.

The issue of uncertainty and the potential threat to Ontario solar manufacturers brings up a dilemma that was touched upon in the previous paragraph. Ontario solar manufacturers cannot compete with foreign competition (particularly China, who manufactures very cheap solar panels) without the domestic content clause of the FIT program.  In the opinion of some panelists, we are wasting our efforts propping up an industry that is not meant to be. By forcing solar installations to be manufactured in Ontario where it is more expensive to do so, the final cost of the installation becomes artificially high, which can discourage investment. By getting rid of the domestic-content clause, overall prices will be driven down and more people will be willing to install solar panels. As well, with increased installations there will be more jobs available to people. What we have here is a fundamental difference in vision for the future of the solar industry in Ontario. Do we want to prop up manufacturing in Ontario and further develop our green-energy sector, even if prices are driven up? Or do we want to scrap manufacturing, and instead focus on the cheap installation of solar energy? It is tough to choose a side. We want Canada to play an active role in solar energy on an international level, and having a strong manufacturing sector is a way to do that. However, the ultimate goal of solar energy is to provide clean power on a large scale, and the way to do that is by making is cheap enough that more people will buy it. In any case, the panel highlighted that one of the biggest questions in the next few years will be whether or not Ontario has a future in solar manufacturing.

Another point that was stressed by the panel was the need to communicate with the public. Solar energy creates jobs through manufacturing and installation, and there are financial benefits to those who own installed systems through the FIT program. These aspects need to be stressed to the public to help drum up support for the industry. Public support will ultimately lead to political support, which will strengthen the industry, and make it immune to changes in government. Looking at the energy sector as a whole, solar is at an advantage when it comes to public relations. Coal is polluting and dangerous to the environment and health.  Hydroelectric power is clean, but does irreversible damage to ecosystems. Nuclear power, while also clean and safe, still has a potential for catastrophic failure and its relationship with the public has always been strained; the accident at Fukushima is still fresh in people’s minds. Wind power is safe and clean, but often faces opposition from people who don’t necessarily have any grudge against it, but don’t want turbines built near their homes. This is where solar power stands apart from other power sources. It is safe, clean, renewable, and is more favourable to wind when installed near communities. Not to mention that it creates jobs, and through the FIT program average homeowners can make money from it. Considering all these aspects, acceptance of solar power is easy to sell to the public. With more money invested in advertising campaigns, we can rally more support behind solar power in Canada.

The use of renewables is growing across the world. Germany is leading the way, with over 24 GW of installed solar capacity in 2011 [3]. This accounts for almost 15% of their total power capacity. In Canada for 2011, solar accounted for only 0.01% of energy production [4].  Solar power is still in its infancy in Canada, and there is a lot of work to be done if we plan on becoming a world leader in renewable energy. Despite the uncertainty in Ontario’s solar industry, and in what the future may hold, one thing is for certain: solar power here to stay.

Me (1)

-Kevin Boyd, MASc Candidate, Year 1, McMaster University, Ontario

[1]. http://www.theglobeandmail.com/report-on-business/industry-news/energy-and-resources/wto-rules-against-ontario-in-green-energy-dispute/article5461941/

[2]. http://m.gowlings.com/knowledgecentre/publicationPDFs/20120615_Gowlings-Ontarios-FIT-Domestic-Content-Requirements_EN.pdf

[3]. http://www.energici.com/energy-profiles/top-10-reports/item/5075-solar-installed-capacity-2011

[4]. http://www.electricity.ca/media/Electricity101/Electricity%20101.pdf

Among various solar cell technologies, dye sensitized solar cells (DSSCs) have attracted widespread commercial and academic interest due to their relatively high efficiency and low production cost [1-5].

In DSSCs, dye molecules undergo optical excitation, followed by rapid electron transfer to TiO2.  The ionized dye molecules are then reduced by iodide ions (I) in the electrolyte, which form triiodide ions (I3). The counter electrode uses electrons that flow from the photoelectrode, through the external circuit, to reduce triiodide ions back to iodide, completing the cycle [6, 7].

The dye sensitizer plays a critical role in the light harvesting. Recently, the highest power conversion efficiency of DSSCs based on the Zn-complex dye has achieved 12.3% [8]. But typically ruthenium based complexes are well known to get higher efficiencies. Ruthenium is a rare and potentially toxic heavy metal and ruthenium complexes are expensive. So, there is a need to develop new precious metal-free dye sensitizers that can replace the traditional ruthenium sensitizer. In recent years, organic dyes have attracted lot of researchers because of their variety of molecular structures, high molar extinction coefficient, low cost and simple and environmentally friendly preparation process. In the last decade, many investigations on p-conjugated molecules with donor–acceptor moieties, such as oligothiophene [9], indoline [10], triphenylamine [11] and coumarin [12] have been conducted.

To catalyze the triiodide reduction reaction, platinum is typically used [13, 14].  The high cost and limited availability of platinum is not compatible with a low-cost sustainable technology.  Therefore, researches have been investigating various alternative catalysts, including cobalt sulfide [15-18], carbon black [19-21], graphite [22, 23], graphene [24, 25], and carbon nanotubes [26].

Researchers are also investigating the possibility of fabricating DSSCs on low-cost substrates, instead of transparent conducting oxide (TCO). Typically the TCO is a fluorine-doped tin oxide (FTO), which accounts for approximately 50% of the total cost of DSSCs [27]. Also, these substrates have several advantages over TCO, i.e., low weight, bendability, portability, and high strength. Conductive substrates such as indium tin oxide (ITO)-coated polyethylene terephthalate (PET) film [28], ITO-coated polyethylene naphthalate (ITO-PEN) film [29], composite structure consisting of electrospun polyvinylidene fluoride (PVDF) polymer nanofibers and TiO2 nanoparticles [30] have been reported.

With these advancements, it is possible that DSSCs will be good competitors to their rivals in the future.

-Hafeez Anwar

 

References

1. Brian, O.; Graetzel, M., A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature (London) 1991, 353, 737-740.

2. Asbury, J. B.; Ellingson, R. J.; Ghosh, H. N.; Ferrere, S.; Nozik, A. J.; Lian, T. Q., Femtosecond IR study of excited-state relaxation and electron-injection dynamics of Ru(dcbpy)(2)(NCS)(2) in solution and on nanocrystalline TiO2 and Al2O3 thin films. J Phys Chem B 1999, 103 (16), 3110-3119.

3. Peter, L.M.;Wijayantha K.G.U., Electron transport and back reaction in dye sensitised nanocrystalline photovoltaic cells. Electrochimica Acta 2000, 45 4543–4551.

4. Heimer, T. A.; Heilweil, E. J.; Bignozzi, C. A.; Meyer, G. J., Electron injection, recombination, and halide oxidation dynamics at dye-sensitized metal oxide interfaces. J. Phys. Chem. A 2000, 104 (18), 4256-4262.

5. Gratzel, M., Photoelectrochemical cells. Nature (London) 2001, 414, 338-344.

6. Park, N. G.; Kang, M. G.; Kim, K. M.; Ryu, K. S.; Chang, S. H.; Kim, D. K.; van de Lagemaat, J.; Benkstein, K. D.; Frank, A. J., Morphological and photoelectrochemical characterization of core-shell nanoparticle films for dye-sensitized solar cells: Zn-O type shell on SnO2 and TiO2 cores. Langmuir 2004, 20 (10), 4246-4253.

7. Lee, J. J.; Coia, G. M.; Lewis, N. S., Current density versus potential characteristics of dye-sensitized nanostructured semiconductor photoelectrodes. 1. Analytical expressions. J Phys Chem B 2004, 108 (17), 5269-5281.

8. A. Yella, H. W. Lee, H. N. Tsao, C. Yi, A. K. Chandiran, M. Nazeeruddin, E. W. Diau, C. Y. Yeh, S. M. Zakeeruddin and M. Gratzel, Science, 2011, 334, 629.

9. Liao, Kung-Ching; Anwar, Hafeez; Hill, Ian; Vertelov, Grigory; Schwartz, Jeffrey. Comparative Interface Metrics for Metal-Free Monolayer-Based Dye-Sensitized Solar Cells. Applied Materials & Interfaces. Accepted for publication (November 9, 2012).

10. S. Ito, H. Miura, S. Uchida, M. Takata, K. Sumioka, P. Liska, P. Comte, P. Pechy and M. Gr€atzel, Chem. Commun., 2008, 5194.

11. S. Hwang, J. H. Lee, C. Park, H. Lee, C. Kim, C. Park, M. H. Lee,W. Lee, J. Park, K. Kim, N. G. Park and C. Kim, Chem. Commun., 2007, 4887.

12. Z. S. Wang, Y. Cui, K. Hara, Y. Dan-oh, C. Kasada and A. Shinpo, Adv. Mater., 2007, 19, 1138.

13. Papageorgiou, N., Counter-electrode function in nanocrystalline photoelectrochemical cell configurations. Coordin Chem Rev 2004, 248 (13-14), 1421-1446.

14. Yoo, B.; Lim, M. K.; Kim, K.-J., Application of Pt sputter-deposited counter electrodes based on micro-patterned ITO glass to quasi-solid state dye-sensitized solar cells. Current Applied Physics 2012, 12 (5), 1302-1306.

15. Wang, M.; Anghel, A. M.; Marsan, B. t.; Cevey Ha, N.-L.; Pootrakulchote, N.; Zakeeruddin, S. M.; Grätzel, M., CoS Supersedes Pt as Efficient Electrocatalyst for Triiodide Reduction in Dye-Sensitized Solar Cells. Journal of the American Chemical Society 2009, 131 (44), 15976-15977.

16. Lin, J.-Y.; Liao, J.-H.; Chou, S.-W., Cathodic electrodeposition of highly porous cobalt sulfide counter electrodes for dye-sensitized solar cells. Electrochimica Acta 2011, 56 (24), 8818-8826.

17. Lin, J.-Y.; Liao, J.-H.; Wei, T.-C., Honeycomb-like CoS Counter Electrodes for Transparent Dye-Sensitized Solar Cells. Electrochemical and Solid-State Letters 2011, 14 (4), D41-D44.

18. Lin, J.-Y., Mesoporous Electrodeposited-CoS Film as a Counter Electrode Catalyst in Dye-Sensitized Solar Cells. Journal of The Electrochemical Society 2012, 159 (2), D65.

19. Murakami, T. N.; Ito, S.; Wang, Q.; Nazeeruddin, M. K.; Bessho, T.; Cesar, I.; Liska, P.; Humphry-Baker, R.; Comte, P.; Pechy, P.; Gratzel, M., Highly Efficient Dye-Sensitized Solar Cells Based on Carbon Black Counter Electrodes. Journal of The Electrochemical Society 2006, 153 (12), A2255-A2261.

20. Murakami, T. N.; Grätzel, M., Counter electrodes for DSC: Application of functional materials as catalysts. Inorganica Chimica Acta 2008, 361 (3), 572-580.

21. Li, P.; Wu, J.; Lin, J.; Huang, M.; Huang, Y.; Li, Q., High-performance and low platinum loading Pt/Carbon black counter electrode for dye-sensitized solar cells. Solar Energy 2009, 83 (6), 845-849.

22. Acharya, K. P.; Khatri, H.; Marsillac, S.; Ullrich, B.; Anzenbacher, P.; Zamkov, M., Pulsed laser deposition of graphite counter electrodes for dye-sensitized solar cells. Appl. Phys. Lett. 2010, 97 (20).

23. Veerappan, G.; Bojan, K.; Rhee, S.-W., Sub-micrometer-sized Graphite As a Conducting and Catalytic Counter Electrode for Dye-sensitized Solar Cells. ACS Applied Materials & Interfaces 2011, 3 (3), 857-862.

24. Wang, X.; Zhi, L.; Mullen, K., Transparent, Conductive Graphene Electrodes for Dye-Sensitized Solar Cells. Nano Letters 2007, 8 (1), 323-327.

25. Guai, G. H.; Song, Q. L.; Guo, C. X.; Lu, Z. S.; Chen, T.; Ng, C. M.; Li, C. M., Graphene- counter electrode to significantly reduce Pt loading and enhance charge transfer for high performance dye-sensitized solar cell. Solar Energy 2012, 86 (7), 2041-2048.

26. Anwar, Hafeez; George, Andrew.E.;Hill, Ian. Vertically-aligned carbon nanotube counter electrodes for dye-sensitized solar cells. Solar Energy. Accepted for publication (November 20, 2012).

27. Yen, Chuan-Yu, Shu-Hang Liao, Min-Chien Hsiao, Cheng-Chih Weng, Yu-Feng Lin, Chen-Chi M. Ma, Ming-Chi Tsai, Ay Su, Kuan-Ku Ho, and Po-Lan Liu. “A Novel Carbon-based Nanocomposite Plate as a Counter Electrode for Dye-sensitized Solar Cells.” Composites Science and Technology. 2009, 69(13), 2193–2197.

28. M.D¨ urr, A.Schmid,M.Obermaier,S.Rosselli,A.Yasuda,G.Nelles,Low- temperature fabricationofdye-sensitizedsolarcellsbytransferofcomposite porous layers,NatureMater.4(2005)607–611.

29. T. Miyasaka, M. Ikegami, Y. Kijitori, Photovoltaic performance of plastic dye- sensitized electrodes prepared by low-temperature binder-free coating of mesoscopic titania, J. Electrochem. Soc. 154 (2007) A455–A461.

30. Yuelong Li,ab Doh-Kwon Lee,a Jin Young Kim,a BongSoo Kim,a Nam-Gyu Park,c Kyungkon Kim,d

Joong-Ho Shin,e In-Suk Choi*e and Min Jae Ko*.Highly durable and flexible dye-sensitized solar cells fabricated on plasticsubstrates: PVDF-nanofiber-reinforced TiO2 photoelectrodes. Energy Environ. Sci., 2012, 5, 8950.

Industry is steadily marching the cost of current photovoltaic technology downwards and it appears likely that photovoltaics will become competitive across most markets in the coming years and decades [1]. Many of these cost reductions will come from improvements in manufacturing, installation and in smoothing the permitting process rather than improvements in basic science [2]. This is good news for those of us yearning for a renewable energy infrastructure.

While current technologies are making their way to markets, researchers in basic science already have their eye on the next generation of technologies that will make photovoltaics even more efficient and competitive.

The efficiency of a photovoltaic cell describes the ratio between energy contained in the electricity generated by the cell to the energy of sunlight on the cell. Thermodynamics limits exist for the efficiency that no amount of innovation can overcome. This maximum theoretical efficiency is known as the Shockley-Queisser limit [3] and is only 33.7%, for the simplest photovoltaic architectures, known as single-junction devices. We would like to be build cells that operate at the thermodynamic limit, but in practice even the best research grade cells under-perform. Manufactured cells generating electricity in the market today typically only operate at an efficiency of 10-20%.

One well known mechanism to improve the overall efficiency is to couple several simple devices together into what is known as a multi-junction device. Today the best research grade multi-junction cell is 43.5%, a significant improvement. A recent commentary in Nature Materials[4] outlines a set of proposals for doing even better. The authors argue that recent innovations in the control of light made possible by nanotechnology, such as nano-sized optics, should allow us to not only build better multi-junction devices but also move closer to the thermodynamic limit for single-junction devices. Combined they argue that their plan could allow us to build devices with efficiencies between 50-70%.  Such an improvement would mean that for equally sized modules, 2.7 to 7 times more electric power could be generated compared to today’s photovoltaic modules.

So while industry continues to push costs of today’s technology down towards mainstream adoption, scientists and engineers around the world are already planning and developing new technologies that will lead to even more efficient, more competitive photovoltaic modules in the coming years.

-Joshua LaForge, PhD Candidate in Electrical and Computer Engineering Department, University of Alberta

Josh LaForge

[1] Technology Roadmap — Solar Photovoltaic Energy (International Energy Agency, 2010); http://www.iea.org/papers/2010/pv_roadmap.pdf

[2] Alan Goodrich, Ted James, and Michael Woodhouse. Residential, Commercial, and Utility-Scale Photovoltaic (PV) System Prices in the United States: Current Drivers and Cost-Reduction Opportunities. NREL Technical Report. February 2012. NREL/TP-6A20-53347

[3] Shockley Queisser Limit. Wikipedia. http://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limit

[4] Polman, A., & Atwater, H. a. (2012). Photonic design principles for ultrahigh-efficiency photovoltaics. Nature materials, 11(3), 174–7. doi:10.1038/nmat3263