Today, it is clear that the current trends in energy consumption especially oil cannot be sustained for much longer because the scarcity of fuel and minerals is making the future more uncertain. Consumption of fossil fuels has also highly contributed to global warming, depletion of the ozone layer and environmental imbalance, which is a huge threat to the future of humanity. Several other factors like the fast-growing population have raised concerns about the limited amount of energy resources available to satisfy the demand.
Therefore, a shift to renewable energy sources is necessary.
A shift to renewable energy sources today is supported by government policies emphasizing the use of green energy, businesses competing for market and household owners saving energy cost as renewable energy sources are less expensive. On the other side, renewable energy sources are also hard to control because it is difficult to balance production and generation in case of unpredictable generation. However, we can control our consumption and thus balance the generation and consumption.
This research focuses on implementation of solar PV power into an electric vehicle powered directly through solar PV panels placed on the horizontal surfaces of the car. The solar vehicle is a step in reducing the consumption of now-renewable sources of energy as they reduce human dependence on fossil fuels. Solar vehicles are the future of the automobile industry because they are easy to manufacture, very user friendly, less maintenance is required in comparison to other conventional vehicles and they are highly feasible. Other advantages of the solar vehicles include cost effectiveness and very eco-friendly since they are pollution less. However, the disadvantages of solar vehicles include high initial costs, small speed range and unsatisfactory rate of energy conversion approximately 17%
(Connors, 2007).
In this research, we are first analysing the travel patterns of passenger vehicles in two different selected regions and creating a load profile based on the energy demand of the passenger vehicle per day. Then we are calculating how much energy can be generated by the solar panels fitted on the electric vehicle in each of the locations. Finally, we are approximating by how much the energy generated can satisfy the energy demand of passenger vehicles in the selected region.
1.1 Limitations of the work
Previous studies on integration of solar cells into electric vehicles argue that the car is often in motion so a smart and advanced system to optimize the energy capture should be embedded into the car. This is costly and more complex and that accounts to the reason why most solar panels have been preferably installed in parking lots to charge the electric cars.
Studies also show that approximately 3.8 million Exajoules (EJ) of the total solar irradiance reaching the earth’s surface is absorbed. Most of the sun rays are scattered, diffracted and deflected by the earth’s surface. Solar irradiance reaching the earth’s surface hourly is abundant which is difficult to be harnessed by humans annually. For the case of electric cars, it is argued that the solar intensity to provide the solar energy required is dependent on the weather condition but other factors include; the location and time of the day, the angle between the solar irradiance and Photovoltaic (PV) panels and finally the PV surface area.
The angle at which the solar panels are mounted is a crucial factor to consider for optimum efficiency. Unfortunately, this study is restricted to a tilt angle of 0° because the surfaces where the PV module is installed on the vehicle are flat. The performance of the solar PV module is affected by its orientation and tilt angle. This is due to the fact that PV modules generate maximum amount of power when they are directly facing the sun.
Another limiting factor of this study is the surface area available on the vehicle for solar PV installation. The number of solar cells installed affects the amount of power output. It is also unfortunate because the vehicle cannot be made any bigger to accommodate a larger module.
This is because a large car also requires more power to run but also consumer preference for big cars and availability of parking space must be questioned.
Finally, two case studies were considered in this survey which are Finland and Tanzania.
The purpose of analyzing results of this research in two different locations is to compare the solar power output of the PV panel to be installed on the electric vehicle and how much the energy generated could vary from one area to another. However, the limiting factor for the case of Tanzania in this study is the difficulty to acquire accurate travel information of individuals. Therefore, the research was limited to differences in solar irradiation and power output of the two different locations rather than the differences in energy demand for travelling by the individuals.
1.2 Objectives
The aim of this work is to analyse how much energy can be generated by a solar PV panel installed horizontally on the surfaces of an electric vehicle and to what extent the energy generated by the solar PV can contribute in meeting the energy required to run the vehicle.
For this analysis, solar power production in two different parts of the world with different weather conditions are compared. This work also aims to find possibilities of increasing the use of solar energy in the transport sector so as to reduce emissions and the depletion of non-renewable sources of energy.
In order to accomplish this, some of the issues that will be looked at objectively include:
• Examining the travel patterns of individuals by different modes of transportation and finding out if the future energy demand for transport could be met by solar production or if solar power could make a difference in the energy mix for transport in the future.
• Analysing the development of PV modules and expected increase in the efficiency of the solar cells in the future. This will hence increase the power output of the modules.
• Questioning the current vehicle design and analyzing whether the size available for PV installation could be larger in the future.
• Possibility of increasing the energy efficiency in the transportation sector by utilizing both solar energy and power generated from the grid or alternative sources to meet the energy demand for transportation in the future.
• Analysing the battery sizing requirements to address the problem of overgeneration or shortage of generation in different hours of the day by the solar panels as it is unpredictable.
• Possibility of utilizing vehicle-to-grid technology to supply surplus power produced by solar PV modules from the vehicle to power our homes.
1.3 Research methodology
HOMER software that was developed by NREL (National Renewable Energy Laboratory) was used in this study in the design of the power system. Data is fed into the software and the results are simulated based on the techno-economic analysis. HOMER considers all the different constraints and sensitivities in finding the optimal solution for the design of the system. The economic analysis of the system is based on the life-cycle cost of the system (LCC) which consists of the initial capital cost, the cost of installation and the operation costs of the system during its life span. The results of the simulations are meant to satisfy the given demand using the resources and the technology options available and the best configuration is thus selected.
In this study, a combination of the following technologies was considered, namely solar PV system, battery, inverter and grid for back-up to meet the demand. Fig. 1 below illustrates the design of the system for this study.
Figure 1: Simulation software layout for the electrical vehicle study
1.4 Organisation of the thesis
This thesis is made up of six chapters. The system proposed in this research is a solar powered system for the design of a solar vehicle. A brief overview of the key features of the proposed methodology have been provided and below is an outline of the topics discussed in this thesis:
1. Introduction
2. Limitations, research objectives, proposed methods and thesis organization 3. System analysis and description
4. System components 5. Analysis on case studies 6. Simulation results 7. Sensitivity analysis 8. Conclusions 9. References
The material is presented with a view to allow readers at different levels to quickly understand the reason for embarking on this research, the objective of the research and the methods that were used to develop the solar powered system of an electric vehicle including all possible limitations. The system analysis section acquaints the reader with the working principle of the proposed solar powered vehicle design and provides an insight on the surface area available for solar PV installation and energy consumption. The system components section introduces the HOMER software and the input data that was used for calculating and simulating the results of this study.
The remaining sections that include analysis of the case studies of this research, simulation results and sensitivity analysis assist the reader to understand how additional data was collected, analysed and how the results were synthesised. Sensitivity analysis was carried out to demonstrate the impact of changes in one variable to the outcome of the results and finally the last section provides a summary and a review on the objectives of the research.