Curtains, hammock and Sun Cinema - Flexible solar panels from DTU have many uses

The summer showed many creative uses of DTU's flexible plastic solar cells. The Smuk Fest at Skanderborg developed a festival hammock with a solar canopy while a mobile solar powered cinema, The Sun Cinema, was launched at the Imperial Festival in London.

Polymer solar cells have many uses. A few years ago the textile designer Astrid Krogh made a pair of stylish curtains with solar panels that used the sun's rays to produce heat.
The beautiful curtains captured the heat from the sun's rays and also provided power for LED-lamps during the daytime. When the sun set, the captured heat was released from the office, living room or whichever room the curtains were, delivering heat and beauty at the same time.

- The product is not yet finished, but we tested it and even though the project has been dormant for a few years, people have started asking for it, says Astrid Krogh, who got a great response when the curtains were presented at an exhibition at the Danish Design Center in Copenhagen.
Astrid Krogh developed the curtains in collaboration with various innovative companies and DTU Energy, where Professor Frederik C. Krebs describes the ground-breaking curtain concept.
- Denmark has already distinguished itself with the development of cheap plastic solar cells, which enables the utilization of solar energy in a far less resource-intensive way than before. The breakthrough of this curtain is that it combines several energy saving technologies in a familiar function, says Frederik C. Krebs.
And the curtains are not a huge investment if at some point they come into production.

Solar Canopy
At Smukfest Skanderborg 2013, one of the largest, but still very intimate, festivals in Denmark, flexible plastic solar cells were used in another creative way.

The SmukFest festival wants to be associated with sustainable environmental technologies and supported by the innovation network Infinit it gathered a group of knowledge and business partners to make different exhibits at the festival. One of the eye-catching initiatives was a hammock with a very colorful canopy made of flexible solar cells which made it possible for weary festival-goers to take a much deserved nap under the canopy while the solar cells recharged their mobile phones.

- I got the idea for the canopy after reading about Astrid Krogh’s solar curtains. I contacted Frederik C. Krebs at DTU who told me that a canopy could work. The solar cells were ready after a few weeks, and a month later we had the hammock ready for use, says Karin Bech from the Alexandra Institute who designed the solar hammock. 
The hammock hung at the festival area called Love Region and was popular from the beginning. A bit too popular actually. The organizers had imagined people relaxing quietly in the hammock while recharging the mobile phones. The reality was two or three people swaying in the hammock at a time with friends partying around the hammock under a beautiful canopy. After four days the hammock was stolen.
- We had so many using it, that we had to take the solar canopy down for repair. When we returned, the hammock was stolen, says Karin Bech.
- It was a big disappointment for us, as we would have liked to show of hammock in other contexts; also it was intended as part of our collection of IT-textile projects.
Professor Frederik C. Krebs is annoyed too, but he can also smile a little as this is the first time people have actually found one of the department’s solar creations so great, that parts of it were stolen. And although theft is always an unwanted attention, it is also a kind of popular endorsement of flexible solar cells.

Solar Powered Yurt
Imperial College London does not need to steal the flexible solar cells, as the Department of Physics has a solar-powered yurt standing on the roof of the building. A yurt is a portable round tent normally associated with steppe nomads in Central Asia, but in May 2013 physicists at Imperial College created a cinema inside a yurt - powered by 60 small flexible solar cells made by DTU Energy.
- The yurt was an interesting and crazy experiment, says Geraldine Cox, physicist and the resident artist at the Department of Physics. She wanted to combine art and science into an artwork that created light in the darkness, and the yurt had the perfect shape with a hole in the roof and canvas walls.

- I talked with Professor Peter Torok in optics, and we created a prototype film projector using an old overhead projector, a discarded LCD screen and a Raspberry Pi mini computer, which is available for 25 pounds. Ian Bell at the natural lighting company Solatube donated a light catching lens to gather and deliver daylight to the system. Once we proved there was a good chance of the system working, we gathered together a talented and creative team of physicists and electrical engineers to build the cinema for real.

The result was an exhibit showing films on a the circular table top inside the yurt with a power consumption of approx. 25 watts powered by 60 small flexible solar cells at the roof.
- We wanted an independent power source which could generate and store enough energy for up to five hours of usage per day, so we contacted DTU Energy in Denmark and had Roar Søndergaard and Bérenger Roth come along and install the solar panels on the yurt, says Geraldine Cox.
Roar Søndergaard was happy to help, as it was a funny and also a good way to present the technology.
- There are very few in the world that can do what we do, and people are always amazed at how thin and flexible our solar cells really are. Our research in polymer solar cells are usually performed on areas less than 1 cm2, and it is exciting when we scale up and arrive lugging 10-12 square meters of finished modules in suitcases, says Roar Søndergaard. He remembers the trip to Imperial College well.
- Geraldine Cox was delighted and excited with the appearance and performance of the cells. We helped make sure, that the solar cells were installed properly.
Eerie but beautiful
The yurt called The Sun Cinema was launched at Imperial Festival in central London on the 4th of May 2013, and it toured to the Big Bang Science Festival in London. Everywhere it went, the public responded with interest and gave a warm response. The quality of the films shown inside the yurt changed with the weather and passing clouds, bringing a slightly eerie but also beautiful effect.
- I think of the cinema like a poem, a metaphor for discovery. You go into the darkness and see moving images in a pool of light.  Sometimes the image is quite clear and at others dim and you have to look to quite hard to find it in the dim light and wait patiently while your eyes adjust to the darkness. Science can be like that too, says Geraldine Cox about the amazing yurt made of blackout fabric, sand coloured canvas, solar panels and recycled materials.
- Small children were especially fascinated by the changing play of light and tried to touch the images as they passed across the table top, and adults liked it as well.

Thousands of people visited the yurt, saw the films and commented on the idea. Some suggested that the yurt could be used as a kind of mobile cinema in Africa or similar places, but so far the yurt has only made it to the rooftop of the Physics Department, where students and staff can look at it every day, while the physicists continue to measure and monitor the output of the solar cells.

On the way to the museum

- We haven’t got any money left for taking the yurt out to science festivals, but the Museum of Natural History in London has shown an interest in presenting it as part of the Science Uncovered event.

Professor Frederik C. Krebs at DTU Energy likes the idea of the yurt and its flexible solar panels becoming part of an exhibition at the Museum of Natural History. DTU Energy is a world leader in flexible solar panels, and works to ensure that the public investment also benefits the general public in a non-profit way. And a solar powered yurt is a good way of doing so, whether it is part of a science festival or part of an exhibition on a museum. He likes the creative uses for flexible solar panels.

- It's great that we are in a position to supply large quantities of cheap plastic solar cells that perform well and are reasonably durable. We support purposes such as the curtains, the hammock and the yurt because we can, because they are good initiatives, and because it benefits the spread of solar cells in general and plastic solar cells in particular. It will be interesting to see what happens next summer, says Frederik C. Krebs.