Overview Of Solar Cars Engineering Essay

Overview Of solar Cars Engineering EssayRenew fitting brawniness is rattling in the world today as in the near prospective non-renewable sources of energy will become s move machinece. The solar cater car is a step in saving these non-renewable sources of energy. The basic principle of the solar car is to use energy that is lineaged in a bombardment during and after charging it from a solar panel. The charged batteries ar used to drive the motor which serves as an engine and moves the vehicle in a reverse or forth direction.Overview of Solar CarsAdvantagesNo longer pauperizati peerlessd to purchase suck or any other type of fuelSolar cars have no regular expense besides maintenance and repairsDoesnt produce any glasshouse gas emissions so it is environmentally friendlyThe use of solar cars as a combustion engine replacement will signifi stacktly centre greenhouse emissions and improve air quality more or slight the worldSolar cars produce no noiseDisadvantagesSolar car s dont have the identical f number or power as a regular car that runs on gasWhile sunlight is turn, the creation of PV carrels to capture that sunlight is expensive. be for solar panels ar steadily declining (22% cost reduction per doubling of performance volume).The weather stick out directly affect the performance of the car, especially if it is phantom outsidePossible system layoutsFig.ure 1 Basic block draw representation of a solar vehicle extension Wamborikar, 2010. Solar cars argon supply by the suns energy. The main component of a solar powered car is its solar raiment or panel, which collects the energy from the sun and converts it into running(a) galvanizingal energy. The solar stalls collect a portion of the suns energy and store it into the batteries of the solar car. Before that happens, a peak power tracker (maximum power topographic point tracker) converts the energy collected from the solar array to the proper system potentiality, so that the batter ies and the motor can use it. Once the energy is stored in the batteries, it is in stock(predicate) to be used by the DC motor and motor ascendancy to drive the car. The motor controller adjusts the measuring rod of energy that flows to the motor to represent to the throttle. The motor uses that energy to drive the wheels.The primary energy source for a solar powered car is the battery. The battery has a number of idiosyncratic batteries connected privileged which ar in series or parallel. individually battery is typically 6V or 12V, and multiple batteries are connected in series or parallel to acquire the optimum system potential difference. A one battery is made from multiple cells contained within the battery housing. The general battery potential drop is chosen depending on the motors EMF constant and the coveted nominal driving whet.In assure to get the most efficient operation of the drive system, the battery potency is chosen so that the motor controller can operate with minimal pulse width inflection at the maximum speed of the car. Nevertheless, the battery potential difference, especially for lead-acid batteries, fluctuates considerably around the nominal battery voltage, from full charge to maximum discharge. This is why, the nominal battery voltage is chosen so that the lowest possible battery voltage is able to sustain a reasonable speed. An alternative solution to this difficulty is to put in a boost or buck convertor in the motor controller so that a desirable speed can be obtained for any battery voltage.Fundamentals and Application of Photovoltaics in Solar VehiclesThe bond model uses the covalent bonds joining the silicon atoms to tie semiconductor behaviour. In the figure below, it illustrates the bonding and the movement of electrons in a silicon crystal lattice.Figure 2 Representation of covalent bonds in a silicon crystal lattice fount Wenham, 2007At low temperatures, the bonds are intact and the silicon behaves as a n insulator. At high temperatures, some bonds are bewildered and conduction can total by two processes electrons from broken bonds are free to move and electrons from neighbouring bonds can also move into the trap created in the broken bond, allowing the broken bond or jamming to parcel out as if it had a positive charge.It is also possible to shift the balance wheel of electrons and holes in a semi conductor (silicon crystal lattice by doping it with other atoms. Atoms with one more valence electron than the semiconductor are used to produce n-type square. Meanwhile, atoms with one less valence electron results in p-type material (Wenham, 2007). This can be seen in figure 3.Figure 3 ancestry Wenham, 2007Figure 4 Diagram of a P-N JunctionSource Nave, 2005. A p-njunction is formed by joiningn-type andp-type semiconductor materials. Since then-type component part has a high electron concentration and thep-type a high hole concentration, electrons diffuse from then-type side to thep-type side. Similarly, holes flow by public exposure from thep-type side to then(prenominal)-type side. If the electrons and holes werent charged, this diffusion process would continue until the concentration of electrons and holes on the two sides were the same. However, in ap-njunction, when the electrons and holes move to the other side of the junction, they leave behind exposed charges ondopantatom sites, which are fixed in the crystal lattice and are unable to move. An electric field forms between the positive ion cores in then-type material and negative ion cores in thep-type material. This region is called the depletion region since the electric field pushes the free carriers out, hence the region is depleted of free carriers. A built in potential (Vbi)is formed due to the electrified created at the junction.Figure 5Source Wenham, 2007When sunlight falls onto the semiconductor material, photons with energy (Eph) lower than the circumstances breakage energy (Eg) inter act insubstantially with the semiconductor, passing through it as if it were transparent. But, photons with energy greater than the band gap energy (Eph Eg) interact with electrons in covalent bonds, using up their energy to break bonds and to create electron-hole pairs which can then move about unaffiliatedly. Also, higher energy photons (red light) are absorbed at hand(predicate) to the surface of the semiconductor than lower energy photons (blue light).The open circuit voltage (VOC) of a solar cell is the voltage measured when there is no on handout passing through the cell. The top side of the solar cell is of negative voltage and the bottom is positive. The open circuit voltage is independent of the size of the solar cell, and is determined by the materials the cell is made of ( think of to adjunct 2). The short circuit electric current (ISC) of a solar cell corresponds to the current measured when the solar cell is short circuited (Fig. 2.11), the voltage equals 0. The e lectric current ows from the bottom (+) of the cell to the top of the cell (-) when the solar cell is below illumination (refer to addendum 2). In advanced solar cars, they include a Maximum Power Point Tracking (MPPT) which maximises the amount of current going into the battery from the solar array by lowering the panels getup voltage which increases the charging amps to the battery. The maximum power output of a solar cell is at the maximum power point (MPP), where the product of voltage and current is a maximum (refer to Appendix 2).When solar cells are connected in parallel, the output current is the sum of the currents from the individual cells, and output voltage remains the same to that of a single cell (proven by data, refer to Appendix 1). When solar cells are connected in series, the output voltage is the sum of the voltage from each cell, where the output current stays the same (proven by data, refer to Appendix 1). Therefore, the optimum alignment for solar cells on a solar car would be in series. This is because the MPPT call for more voltage as it extracts the solar cells output voltage in order to maximize the amount of current going into the battery.Source Blimpy, 2010.How a solar cell whole shebangFigure 6 A diagram of a solar cell.Source Lollini, 2010. The photovoltaic effect used in solar cells allows direct transition of light energy from the sun into electricity, by the generation and transport inside a semiconductor material, of positive and negative electric charges, through the action mechanism of light. This material romps two regions, one exhibiting an excess of electrons, the other an electron deficit, resistively referred to as n-type doped and p-type doped. When the two are brought into get hold of with the silicon, excess electrons from the n-material diffuse into the p-material. The initially n-doped region becomes positively charged and the initially p-doped region is negatively charged. An electric field is thus made b etween them, tending to force electrons foulwards into the n-region and holes back into the p-region. Then a p-n junction is setup and by placing auriferous contacts on the n and p regions, a diode is acquired. When the p-n junction makes contact with light, the photons having energy equal to or higher than the width of the forbidden band or band gap yield their energy to the atoms, where each photon causes an electron to move from the valence band to the conduction band, leaving behind a hole, also able to move around the material thus, giving stand to an electron-hole pair. If a load is to be positioned at the cells terminals, electrons from the n-region will migrate back to the holes in the p-region, by goernment agency of the outside connection, giving rise to a potential difference- an electric current passes.Importance of Correct System approach pattern and Sizing / Non-shadingThe main point that should be kept in understanding while making a solar vehicle is the mounti ng of the solar panel. The panel should be mounted in a great deal(prenominal) a way that it receives maximum sun rays so that it gives maximum efficiency. Since the sun is at a different slant to the ground all the, so the solar panels need to be directed according to this positioning.The ideal situation is when the suns rays are colliding with the panels at a perpendicular angle of 90(proven by data, refer to Appendix 4). Thismaximizesthe amount of energy hitting the panels and being produced. The two factors that affect the angle as such are controlled by the orientations (north, south, east, and west) and the angle of the panels from the ground.The main feature of any solar is its array of solar cells. An ideal solar cell would be made of expensive gallium arsenide which are nearly 30% efficient. However a cheaper alternative can be used such as ultra pure monocrystalline silicon which can reach efficiencies of over 20%. Selecting the solar cell with higher efficiency means th e less surface area needed so the solar vehicle is able to carry less weight and travel at a faster speed. Therefore, itd be recommended to use a small solar panel with a high efficiency rate so then sizing is non important.For maximum power efficiency in a solar powered car, the solar panels should be in full contact with the suns rays. If a single cell is somewhat shaded by in time a small object, it can create a power drop as much as 50%. This is because the cells in a panel are connected in a series string, so if one cell is shaded, then the rest period dont work properly (proven by data, refer to Appendix 5). To reduce the effectuate of shading, the strings are usually kept short and paralleled as much as possible. Having lots of parallel strings is good, because whatever currents are generated can be added together, while the voltage of each string remains relatively similar with or without light. Voltages of parallel strings are taken as the average voltage of each stri ng. An example of how a module business leader be wired is shown below.Source Sanghster, 2006.Safety IssuesSince the solar powered car is run by a DC motor, there are rubber eraser issues with direct current. If a person is electrocuted, electric currents can produce sinful burns in the body, particularly at the points of contact to the circuit, as the galvanizing power dissipates across the bodys resistance. Electric shock can only occur when contact is made between two points of a circuit, and when a voltage is applied across a victims body. Since direct current moves in one direction through a conductor, it has the tendency to incite muscular tetanus, even at low voltages. Victims are often unable to let go of a DC conductor because of the continuous motion and stable voltage. Also, DC electricity tends to make the heart stand still.ConclusionIt is essential that the devise of solar cars are efficient, safe and takes into account the specific requirements and limitations. Fo r example, in order for the solar car to run on solar power it needs a lot of power and an optimum angle needs to be decided to maximise this power output. It is best to use a MPPT to maximize the current going into the battery and to choose an efficient solar array or panel. This being said, the solar car can have a significant impact on the reduction of unhealthy greenhouse gas emissions and help prevent global warming. We need to make use of solar powered cars so that we can reduce our dependence on fogey fuels.