Nuna7 is the first four-wheeled solar car of the Vattenfall Solar Team and has won the World Solar Challenge 2013. This car was the first to use a lens system, concentrators, which brought in more energy than the opponents. The revolutionary asymmetrical design ensured that our air resistance was again very low. Nuna7 was the first to cross the finish line in 33 hours and 3 minutes at an average speed of 90.71 kilometers per hour.
Because the allowed dimensions of the solar car were limited, the seventh Vattenfall Solar Team could no longer fill the top shell of the car with the full allowed 6 square meters with solar cells. Half a solar cell surface remained. To utilize this, the team looked at Semprius concentrators. This is a lens system that focuses a large surface area of sunlight on a small surface solar cell. These cells were folded out when the car was stationary, during control stops and in the morning and evening. The opponents of Nuna7 had not come up with this and this innovation contributed to the profit.
Because Nuna had to have four wheels for the first time, the aerodynamic design was looked at creatively. An asymmetrical design proved to provide the least air resistance, so the driver was placed on the side of the car and the electronics on the other side. This did present a challenge in terms of stability and in terms of steering system, which had to pass through a narrow passage to be able to control the non-steering side. Thanks to this design, the team had a head start in the field of air resistance.
The normal solar cells were also optimized. The Sunpower cells were of unparalleled efficiency. An additional advantage was a new laminate over the solar cells. In addition to the reliable Gocherman laminate, we have applied a new laminate from SunCat this year. This laminate from America has done us a good service.