We’ve been working with two scientists at the top of the photovoltaics (PV) field – Professor Anders Hagfeldt and Professor Sten-Eric Lindquist.
Both scientists are from Sweden and have travelled to the CSIRO Energy Centre in Newcastle to check out our facilities and work with our photovoltaics team…whilst also enjoying summer in the southern hemisphere.
Not only does he play some mean drums in a band called ‘Fat Cotton‘ but Professor Hegfeldt really knows his dye-sensitised solar cells. He’s one of the top 50 scientists in his field! (Watch our short video on the production of dye-sensitised solar cells).
Professor Sten-Eric Lindquist, from Uppsala University, is working with us in our labs, giving us the benefit of his considerable experience in photovoltaics. Professor Lindquist has been examining the properties of semi-conducting photovoltaic materials.
In a neat twist Professor Lindquist was Professor Hagfeldt’s university supervisor (*cough* some 20 years ago).
By Simon Hunter
Our scientists are pretty passionate about their work. So much so that they don’t just take their work home with them – they take it on holiday.
Scientist Scott Watkins recently took this holiday snap of an organic printed solar cell floating in Callala Bay on the NSW south coast. He thought the cell deserved a treat after helping secure funding for a new, $87 million Australia-US partnership in solar cell research. The funding will be used to establish the US-Australia Institute for Advanced Photovoltaics (IAP). This centre will work on solar cells – those that convert sunlight directly into electricity.
The solar cell partnership is a parallel program to the solar thermal research partnership that we reported on back in December.
For CSIRO, our involvement in the IAP represents a great chance to continue our work on manufacturing thin-film solar cells while working alongside new colleagues with deep expertise in existing, silicon-based solar cells. Who knows where this research will take us next.
Our photovoltaics researchers at the Newcastle Energy Centre like to get right into the action when they’re in the lab.
Meet Kenrick Anderson, a photovoltaics experimental scientist. He gets to do fun science things – like monitoring how clean the lab is and filling out forms… no, I mean cool stuff like fabricating new solar cells and testing and comparing how they perform in the sunlight or indoors using a solar simulator.
Want to know more about ‘simulated sunlight’ and what we can do with it? Well, read on. Kenrick has given us his down-to-earth explanation of how one of our measurement tools – a monochromator – helps us understand how solar cells respond to sunlight.
Sunlight contains many different wavelengths of light – it’s a broad spectrum, polychromatic light source. Different types of solar cell respond to different parts of the solar spectrum. To compare these different cells we use monochromatic light – light of a single wavelength– as a means of seeing how a solar cell performs at a particular wavelength. For instance if we take just the light that we can see with our eyes, the wavelengths of visible light start at 400 nanometres and extend out to 720 nanometres.
Do you remember the spectrum by the following acronym?
ROYGBIV (Red Orange Yellow Green Blue Indigo Violet)
Actually, this is in reverse order as red light stops at 720 nanometres and violet starts at 400 nanometres. In nature we see white light being split into the spectrum. Have you noticed the reflection of light as it bounces off water droplets which produces rainbows, or in the interference patterns of an oil slick on water? To reproduce these effects in the laboratory we use a monochromator, like the one pictured below:
A monochromator works using a diffraction grating – a special surface with a series of very fine grooves (about 1000 parallel grooves every millimetre!). When light reflects off the surface the grooves cause the colours to separate out. If you turn a CD over you can see this effect for yourself: a rainbow-like spectrum of colours will be reflected off the disk – it’s a diffraction grating in real life using the even grooves of the CD. Similar surfaces are used within a monochromator to split the light. By changing the angle of the diffraction grating we can choose the wavelength coming from the monochromator. Fortunately, our system is computer controlled and all we need to do is type a number in and out comes the wavelength we are interested in. Job done!
Watch the short movie below showing the monochromator sweeping through the spectrum from 350 nm (in the UV part of the spectrum, just beyond violet) to 750 nm (in the infrared part of the spectrum, just beyond red).
In today’s Newcastle Herald newspaper our blogger Dr Greg Wilson appeared in an article about our cool next generation solar cells made from dyes. We’ve previously shown you how they are made. Greg’s also holding one in the picture below.
We are developing dye-sensitised solar cells (DSC) that can be integrated into the walls, windows and roof top materials of buildings. They need to cover a much larger area to generate the same amount of electricity as the common silicon photovoltaic panel. We can make our DSC pretty colours; one day bill boards and signs might also be made of them (how cool!).
If you read the Newcastle Herald article and want to know a bit more, read on.
From Greg: “…it is not as easy as comparing apples with apples. Like all products, silicon solar cells come in a variety of models – these may range from low cost, compact, 5 Watt modules all the way through to higher cost, high performance, modules in the 200+W range.
The product we are developing is for building integrated photovoltaics (BIPV) where one type of ‘product’ may be a type of solar glass window with a target of 80W output from the window under Standard Temperature Conditions (STC) of 25C. On a hot day, the surface temperature of a PV module can be much higher than the air temperature, perhaps up to 60C. The output of an 80W silicon module would drop from 80W to 69W as the temperature increased while a DSC module output could increase to 88W for the same temperature change under ideal conditions
The silicon PV modules have a negative temperature coefficient whereas organic solar cells like dye-sensitised solar cells or organic PV experience positive temperature coefficients. Of course other factors such as price, availability and module lifetime also have to be considered in making the final technical selection.
Greg has also chatted about the topic on our CSIRO facebook page. Why not become a fan and join the conversation?
The CSIRO Solar blog has made it to 100 posts, and we’ve celebrated it by doing what we do best: harvesting power from the sun.
Photovoltaics research scientist Greg Wilson fabricated this dye sensitised solar cell in CSIRO’s Newcastle lab and I think you’ll agree it’s a pretty great way to commemorate our achievement and show off the technology at the same time.
Click through the pictures below for more details of the fabrication process.
We plan to show you this process in more detail in future posts of the blog.
We’ll also be posting ‘100 facts about solar at CSIRO’ over these next few weeks, so keep an eye out for them.
Click on an icon below to download this image as a desktop wallpaper for your screen size.
Krishna Feron from our Photovoltaics Group recently attended the annual conference of the CSIRO Computational & Simulation Sciences Transformational Capability Platform and took out the prize for the best poster presentation! Krishna’s project uses a supercomputer to simulate the physical processes that make an organic solar cell work, from the absorption of sunlight through to the collection of electricity. Organic solar cells are an exciting new technology that will hopefully allow solar cells to be mass produced for the cost of printing a newspaper.
Krishna says CSIRO’s GPU cluster is already one of the most energy-efficient supercomputers in the world‡ and its application to solar cell research is now making it even more ‘green’!
‡CSIRO’s Supermicro Xeon Cluster is ranked 15 on The Green500 list – a ranking of the world’s fastest and most powerful supercomputers by energy efficiency (June 2011 rankings)
For more information see: The Green500 List