This year I had the honour of attending the IEEE’s 40th Photovoltaic Specialists Conference (PVSC) in Denver, Colorado on behalf of the Photovoltaic Innovation Network (PVIN). PVSC is one of the largest solar energy conferences in the world, bringing people from all over the world together to discuss the recent advances in photovoltaics and the next steps and challenges we face as a community.

By far the most impressive talk I saw this year was from a representative from SunPower Corporation. SunPower is a company that produces and sells solar modules. For many years they have held the record of having the highest efficiency cells for commercial single junction crystalline silicon solar cells. Their solar cell is an all-back contact solar cell, meaning that the metal contact fingers used to extract electrons generated by light are all on the back side of the cell. This innovation completely eliminates the problem more traditional solar cells face, where light is reflected off of the front metal contacts and thus does not enter the cell to contribute to electricity production. Though an all-back contact solar cell is not unique to SunPower, they do it the best! Their talk this year, Towards the Practical Limits of Silicon Solar Cells given by David D. Smith, discussed the recent advances they have made in their high efficiency cells. They have demonstrated a large area, commercially manufacturable cell that is 25% efficient! Now that may not sound like much to the untrained ear, and in fact 25% efficiency was a record set many years ago by Martin Green’s research group at the University of New South Wales in the late 1990’s. However, their cell was extremely expensive to fabricate and was not commercially viable. It was never designed to be sold commercially, but to demonstrate that it is possible to reach such high efficiencies in silicon solar cells. Now, more than a decade later, SunPower has demonstrated that this efficiency can be reached in a commercially viable manufacturing process. Very impressive!

The unveiling of the 25% crystalline silicon solar cell was somewhat bittersweet to me. My own work involves crystalline silicon solar cells, but making cells which are 10-100 times thinner than the currently available commercial cells. 25% efficiency is very exciting, but it shows that research into traditional thicker silicon cells is nearing a close as efficiencies close in on the theoretical maximum. This means that researchers will be turning towards thinner cell architectures, which means I have a lot of competition ahead of me!

Another talk that interested me, An Arbitrary Programmable Solar Simulator Based on a Liquid Crystal Spatial Light Modulator, was given by Tasshi Dennis from the National Institute of Standards and Technology (NIST). Tasshi presented an arbitrary spectrum generator, which splits a white-light source into its spectral components (i.e its component colours) and filters them through a liquid-crystal array. In this way they can create a spectrum that exactly matches that of the sun. This is very important for the testing of solar cells, where an exact spectrum is needed to accurately replicate the performance a cell would achieve in the field. It is useful to be able to generate an arbitrary spectrum because the spectrum of sunlight reaching the surface is highly dependent on geographical location and the sun’s location in the sky. So if you wanted to know how a solar cell would perform in the Sahara desert, for example, you could measure the spectrum there and use your arbitrary spectrum generator to recreate it in the lab. It is also applicable to extra-terrestrial applications such as satellites or the exploration of the surface of Mars.

At the conference I presented a poster on my work involving light trapping in thin crystalline silicon solar cells. I believe it was well received, and I had some excellent discussions with fellow conference attendees. All in all, PVSC 40 was an excellent conference full of fascinating advances in photovoltaics and lots of innovation. I have come back with a lot of inspiration and new directions with which to take my own research. Outside of the conference, several HQP made a trip up to Mt. Evans in the Colorado Rockies. At over 14,000 ft this mountain features the highest paved road in North America, which terminates just a few dozen feet below the summit. Needless to say, the scenery was spectacular and while it is very difficult to breath at such a high altitude (and it is rather cold!), the thin air did not detract from the beauty.

-Kevin Boyd PhD Candidate, Year 1 Department of Engineering Physics McMaster University

Kevin Boyd
PhD Candidate, Year 1
Department of Engineering Physics
McMaster University