The solar cars: a dream? Futurosolare, which is working to create it with the Archimede project, with which it aims to also participate in the "World Solar Challenge 2015". With zero state aid, but many contributions from local companies, Vincenzo di Bella tells how, as soon as the tests are over, they will take the cars around from Syracuse for a "parade" in 9 stages and 1,000 km.
1) What does the Archimedes project mean in the field of solar cars?
For ussolar power represents the most advantageous alternative for world energy development: the Archimedes project was born with this in mind, aimed at developing a high efficiency system for traction of solar cars. We have been working on the project for 5 years now but only for 2 years have we found, with great difficulty, the funds to move from the design to the construction phase. This thanks to the help of many companies who have made their products available free of charge for the construction of the parts of thecar: from carbon fiber fabrics to bonding systems, from resins based on nanotechnologies to very high strength aluminum designed for heavy loads and strong stresses.
2) What levels of energy efficiency have you reached?
The system efficiency calculated is 96% of the power produced by the photovoltaic panels. Once on the road, variables intervene that will make the total efficiency of the system drop by 10% according to our forecasts.
3) What kind of technologies were used in the prototype? Why these choices?
For maximum mechanical efficiency, aiming at the maximum rigidity of the supporting structure but at the same time at a high compression ratio to shocks to obtain the maximum protection of the rider, we used 7000 alloy aluminum: an excellent compromise between flexibility, resistance and lightness.
For the aerodynamic aspect, we relied on the simulation of CFD Computational Fluid Dynamics software to find the resistance to the advancement of the car.
For the propulsion and energy system, to maximize the 1000/1200 watts produced by the photovoltaic panels, it was essential to use an "Energy tank": a highly efficient battery pack managed by an electronic control.
We are also in the testing phase of a kinetic energy recovery system called K.E.S.S Acronym for Kinetic Energy Storage System. It is a system similar to the kers used in the Formula 1 single-seaters, with the difference that it is not batteries that are charged with the kinetic energy accumulated during braking or when the accelerator is released, but a system of very high capacity super capacitors capable of receive a lot of energy in a few moments and release it just as quickly.
4) What are the costs of these solar cars? Do you receive incentives from the state?
Our design philosophy is to use easily available material and common uses to have lower costs. We plan to stay within the 10 thousand euro mark for the construction of the entire car, it is clear that this is a theoretical figure because we are in the testing phase and if some tests are not successful, alternatives will have to be found. As for external contributions, our association is largely self-financed by the members. We have never received state contributions, even if requested several times, but we are very grateful to the many companies, instead, they collaborated and collaborate with us by providing us with construction materials free of charge.
5) What kind of tests will the solar cars subject to the prototype?
We will test the electronic circuits and their degree of reliability as the operating temperatures vary, first of all, then we will move on to testing the mechanical part on the road using the old Syracuse car circuit. At the end of this phase we will bring thesolar car on the roads of Sicily, in 9 Municipalities, to return to Syracuse after traveling about 1000 km.
6) What type of batteries will you choose? With what advantages for the environment?
We still have to choose between two types of lithium batteries: lipo and lifepo4. The former have a higher specific power (weight / power ratio) but have the disadvantage of having a charge / discharge cycle of about 700 cycles. The latter, even if their power weight is less than lipo, have the great advantage of having about 2000 charging cycles and the electrolyte used is more stable at high temperatures.
7) What type of solar panel do you use? Why this choice and what% of return does it guarantee?
The solar cells that make up the panel of about 6m squares are monocrystalline silicon with an average efficiency of 17/18%. This is what the market offers as the maximum yield for commercial use, in reality we would like to use multi-junction Ga, InP / GaAs / Ge photovoltaic cells, to which we have not accessed as products for aerospace construction with yields of 30/37%.