Perhaps it is the subtle challenge made by the silicon PV industry that remains most clear in my mind after returning to the SUNLAB after a week of technical presentations at EU-PVSEC 2013.  The rivalry is not new.  In fact, statements asserting silicon’s dominance represent a broad summary of the opinions conveyed about the future of the photovoltaic industry at the conference.   Those statements likely would have slipped transparently through my tired conscience if not for the nagging objection that the arguments for studying alternative PV technologies seem to ring as true today as they did when the price of silicon panels was still at $2.00 per Watt.   So does the emphasis on the plummeting price of flat panels mean that all of us working on so called “fringe technologies” (which include, by deployment volume, higher efficiency CPV and lower efficiency thin film strategies along with pretty well everything else the PVIN funds) should pack it in and start working on evolutionary improvements to current state of the art solar cells with the University of New South Wales (UNSW)?  I think not.

Mark Yandt

Mark Yandt
PhD Candidate, Year 3
SUNLAB, University of Ottawa

Let’s give credit where credit is due.  Silicon photovoltaic (PV) manufacturers have worked extremely hard to transfer technology developed for the integrated circuit and telecommunications industries to the production of PV cells with the intention of producing clean energy and to take a bite out of a multi-trillion dollar energy market. History has shown that transferring technical expertise between related disciplines is not only intellectually interesting, it is just good business.  Flat panels are easier to explain to investors and customers because the technology used to make them is more established and in terms of installation is often less complicated.  Why go to the trouble of reinventing the wheel if technical understanding in one discipline can be copied and used to add value in another.  Sounds like a money making venture to me!

Even Martin Green (UNSW) agrees that efficiency is a key driver for photovoltaics.  Few would argue this math.  By that argument and taking into consideration the fact that there are several technologies that are making annual efficiency gains comparable to or greater than silicon technology (both CPV and organic cells at ~0.8% absolute/year), it is conceivable that with the right timing and investment, any of a number of alternative strategies could capture significant electricity market share.  The only scenario that is sure to fulfill the one-technology prophecy is the one in which researchers stop considering so called fringe technologies all together.  But this would require researchers to stop thinking outside the box and if that were to happen we would have a much, much bigger problem on our hands.

Richard King (Spectrolab) showed once again the efficiency benefit of a 6 junction device used for terrestrial applications to highlight the fact that multijunction devices are not yet reaching physical limits to performance and that we can continue to expect new, higher efficiency CPV devices in the near term.  The story is not the same for single junction cells in the silicon industry.  Efficiency gains are harder and harder to come by, and costs are being driven down by a number of interesting market dynamics spurred on by an excess capacity of silicon feedstock.  The path to increased efficiency may be via the addition of more junctions on top of silicon cells but lattice constants are a major physical barrier and junctions that can be painted/printed on the top of silicon cells are still largely conceptual.  In contrast, the issues preventing investment and deployment in the CPV industry are often referred to as engineering issues which are related to reliability since trackers and concentrating optics add mechanical and thermal challenges to systems that are already optically and electrically complicated.  These types of issues and the associated costs tend to be resolved and reduced, respectively, according to a learning curve which is a function of deployment.  With a keen interest in hearing a convincing rebuttal, I will suggest that it looks to me like higher efficiency alternatives still have a compelling future.

Regardless of my biased interest in CPV and the other incredibly interesting research projects supported by the PVIN, the fact that silicon is “winning” when measured by cumulative deployment, should not be in any way disappointing or discouraging but instead motivating.  Remember that as an industry we are on the same team regardless of what PV technology we are currently studying.   There is ultimately room for more than one “winner” and until solar becomes as ubiquitous as we in the PVIN know it will be, market share will be relatively easy to steal.  Besides, for the time being, there are still massive barriers to entry into the electricity market that renewable energy producers are going to have to face together such as the adoption of distributed capacity into the existing grid infrastructure.

Finally, we must remember that as students we have only a short time to try to contribute substantially to human knowledge without the requirement for immediate profitability.  We have the luxury of furthering the technology that we WANT to succeed without worrying about which technology is currently “winning”.  Thus we have the liberty to pursue creative solutions to problems that our predecessors have found to this point insurmountable.  We should not limit ourselves by restricting our focus to established technologies but feel free to take a shot at a new solution.  As Wayne Gretzky once said, “You miss 100% of the shots that you don’t take”.