Archives for the month of: May, 2013

Last year I had the opportunity to attend two big international Photovoltaics (PV) conferences.  The keynote speeches at both conferences discussed the future of crystalline silicon (c-Si) and ideas for high efficiency low cost c-Si PV technology. With less expensive organic PVs in the market and efficiency mark of thick crystalline silicon cells jammed at ~ 26% , these issues have been the hottest break-time discussion topics among people working in c-Si PV.

Recently, a very interesting article on “exotic silicon” by researchers at University of California, Davis on January 25, 2013 in Physical Review letters stirred up excitement in c-Si PV world. This exotic silicon, also called BC8 silicon, is a type of silicon that can be formed under extremely high pressure and is still capable of maintaining its stability at normal pressures. So what’s exotic about this silicon?? It can produce multiple electron hole pairs per incident photon in contrast with one e-h pair/photon generation in normal c-Si! The simulations run through the National Energy Research Scientific Supercomputing Center at the Lawrence Berkeley Laboratory predicted ~ 42 % efficiency in BC8 silicon solar cells under one sun that can be increased to ~ 70% by concentrating sunlight on the cell.

Wondering if you can actually make this exotic silicon? The answer is yes! Joint research between MIT and Harvard University shows that one can convert ordinary c-Si into high efficiency exotic silicon merely by shining it with laser light or by applying chemical pressure.

Conclusion: Silicon is an exotic element.  I think c-si will keep holding its share in future PV market with its surprising properties and contribution from researchers.

Check out the links and papers below for more information on this exciting research

  1. Lin, Yu-Ting,  Sher, Meng-Ju, Winkler, Mark T., Mazur, Eric,  Gradecak, Silvija Pressure-induced phase transformations during femtosecond-laser doping of silicon, Journal of Applied Phyics 5-110 (2011)
  2. Sher, Meng-Ju, Franta, Benjamin, Lin, Yu-Ting, Mazur, Eric, Gradecak, Silvija The origins of pressure-induced phase transformations during the surface texturing of silicon using femtosecond laser irradiation, Journal of Applied Phyics 8-112 (2012)
  3. http://www.energymatters.com.au/index.php?main_page=news_article&article_id=3572

Kitty Kumar

-Kitty Kumar

Ph.D Candidate, Year 4

University of Toronto, Toronto, Ontario

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We are constantly inundated with projections, estimates, and forecasts of our future global and photovoltaic (PV) energy requirements. How much energy will we need by 2050? How much of our energy should come from PV? How much PV capacity can we install by 2020? Will that be enough?

I thought it would be interesting to see how we’ve done on our last decade of projections for global PV installations. The European Photovoltaic Industry Association (EPIA) is among various organizations that project and report the status of the PV market. From a series of EPIA’s Solar Generation (SG) reports ranging from SG1 (2001) to SG6 (2011) I looked at year-over-year projections for total global installed PV capacity, and plotted them alongside the actual installed values (see Figure 1).

Figure 1 for Ryan Tucker's blog

Figure 1 Cumulative installed photovoltaic capacity values and estimates from several EPIA reports.

It turns out that we’ve consistently beat the projections by large margins. In fact, the 2010 installed value (>39 GW) is more than a factor of three higher than the 2001 projections for that year (~13 GW). We can see from the plot in logarithmic scale that the installed capacity keeps jumping off of the exponential prediction curves.

The industry has made well on its promises. We must realize that the solar industry is in an enormous state of growth, but only because we are so far behind. This exponential growth is not sustainable for the industry. Certainly there has been amazing growth in the past decade, and we hope that this trend will continue for the following decade or two. Beyond that, let’s just hope that the total capacity is a significant portion of the global energy supply, and the industry can happily transition into a more steady growth state. In the meantime, I’m happy to take every megawatt of PV that we can get!

 

Ryan Tucker

-Ryan Tucker

Ph.D Candidate, Year 4

Department of Electrical Engineering, University of Alberta