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Master's Thesis Andreas Wurm

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Evaluation of the Potential of Automotive Solar Roofs inMexico and Germany in due Consideration of Economical and Ecological Aspects Using a SimulationModel

Reduction of climate-damaging greenhouse gases like CO2 is one of the central challenges of the
worldwide efforts to achieve an eco-friendlier energy mix. Several measures are taken in order to
limit the increasing world average temperatures. Besides the improvement of energy efficiency and
the reduction of energy consumption, the use of renewable energy sources play a decisive role in
these efforts.
Generating electricity by using solar radiation in photovoltaic cells represents a part of the development
of renewable energy, which is becoming highly important. In 2012, the capacity of worldwide
installed photovoltaic plants was about 100 GWp. The average solar insolation in Mexico is more
than 5.0 kWh
m2Ąd , making it one of the countries with the highest solar radiation worldwide. However,
the installed capacity of photovoltaic plants was only 0.038 GWp in 2012. In contrast toMexico, the
average insolation in Germany is only about 2.9 kWh
m2Ąd , but installed capacity is by far higher than in
Mexico (32.7 GWp in 2012).
Solar power by photovoltaic means is not only used on roofs of buildings or big energy farms but
also on roofs of electric, hybrid, and conventional vehicles. Due to its low emission characteristics,
electric cars are environmentally advantageous compared to petroleum based vehicles. Some
series-production automotive solar roof applications already exist, using electrical energy. For example,
to power the air ventilation system or to charge a high voltage battery. Automotive suppliers
expect different energy earnings, varying from 300 to 1,000 km additional driving range per year. In
this thesis, the potential of automotive solar roofs in Mexico and Germany will be evaluated taking
into consideration both economical and ecological aspects.
In order to quantify the energetic potential, a model of an automotive solar roof is created using
mathematical software and taking into consideration the I-V characteristics of monocrystalline solar
cells. The model contains the geometry of an automotive roof to calculate the angles of incidence
of the solar radiation in every photovoltaic cell. A thermal model of the roof makes it possible to determine
the efficiency of the photovoltaic cells as a function of the temperature. Average weather
data of Mexico and Germany allows the simulation of the electrical power supply of every hour of
the year.
After simulating the expected power supply, the thinkable applications like driving battery charging
or electrical power supply for devices like radio, light, or ignition are evaluated taking into consideration
technical feasibility. The results will be compared to calculations of manufacturer companies in order to verify or disprove the expectations and propose improvement measures. Simulation runs
particularly focus on the question, in which way the curved arrangement of series-connected solar
cells influences the resulting I-V characteristics and output power.
The potential of automotive photovoltaic roofs will be evaluated on one hand from an economical
and on the other from an ecological point of view. Finally, both the economical and the ecological
aspects will be evaluated in the conclusion.