Institute of Energy

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Experimental study on the effect of different etching methods for texturization of mono-cSI wafers required for the fabrication of solar cells
(University of Dhaka, 2016-05-02) Abedin, Atia
Etching methods were developed for texturization study on mono-cSi wafer required to have a fabrication processing of solar cells. The etching effects on quantum efficiency of solar cells. We compare three different etching methods (Recipe 1: CH 4 O/ C 3 H 6 O, recipe 2: NaOH/HF, Recipe 3: HNO /HF ) on surface texturization of mono-crystalline Si wafers in an KOH/IPA solution. With a better saw damage removal method bigger pyramids can be seen than those at the more contaminated zones, causing homogenous textured figure and reflectance uniformity on wafer surfaces. Spectral response measurement system (200mv/ 400nm-1200nm) and Scanning electron microscope (operated at 20 KV, magnification: ×5000- ×50000) were used to differentiate the etching quality of several recipes by analyzing change of reflectance and surface morphology respectively. Bigger pyramids found on mono-cSI wafer etching by method 1, which reflects the quality of reflectance of wafer. Spectral response of this wafer was also studied. Percentage Reflectance with respect to mirror image was measured from graphical analysis. Saw damage removal process may require to be customized to attain consistent and desired texturization outputs.
Experimental study on optical characterization of mono crystalline silicon solar cell
(University of Dhaka, 2016-05-04) Chowdhury, Nusrat
The experimental works have been done on the optical characterization of mono crystalline solar cell by Surface Photo Voltage (SPV) measurement for fabricated solar cell by observing minority carrier diffusion length (L) & life time (τ). The core objective of this research was to reduce the cost of solar cell and increase the efficiency by analysis the optical characterization. As the PV cell is one kind of photo diode so the surface photo voltage is very important part of characterization of cell fabrication. There is a direct relation between the minority carrier lifetime and solar cell efficiency. The method of SPV is a contactless system that helps to analysis the optical characterization of semiconductors. It measures the diffusion length of minority carriers in the region of essential light absorption inside solar cells and wafers. The minority carrier diffusion length, L is an important factor for cell efficiency and spectral response of the mono crystalline silicon solar cell. It is also necessary for evaluation of the p-type silicon wafer. In this experiment the surface photo voltage (SPV) of fabricated solar cells have been analyzed and observed minority carrier flow by Light Current Voltage (LIV) tester as it represented the quality of fabrication process and efficiency of the solar cell. A simple computer-controlled, normal incidence measurement system was designed for SPV measurements of minority carrier diffusion length and lifetime of Si-solar cell. Measurement system is based on a mini monochromator driven with a steeper motor to vary wavelengths in 400-1200 nm spectral range . Light induced surface photo voltage is measured as a function of the wavelength. SPV is measured using a Standard Research 510 lock in amplifier. A LabVIEW interface is used for system control and data acquisition. After calculating the experimental data obtained from mono crystalline silicon solar cells measurement, minority carrier diffusion length and life time were calculated and it was 92 μm and almost 3.135 μs respectively. By using solar simulator‘s (Sun Simulator K3000 LAB55) platform at 25oC efficiency was measured and it was 16.04%.
Technology for photovoltaic data monitoring by a central server system
(University of Dhaka, 2016-05-04) Siddique, Md. Abu Bakar
The condition of the Solar Photovoltaic (PV) systems should be monitored continuously for obtaining better performance and timely maintenance. PV systems installed at different locations with monitoring capabilities provide information in advance about performances. Based on this information, maintenance can be carried out to improve the performance and life cycle of the system, thereby also reduce overall operating cost. Quality of several monitoring systems for local and remote application, based on the techniques of communication, such as, computer to computer, embedded system to computer (GSM) and embedded system to embedded system (GSM, GPRS). In different locations solar radiation, solar day, latitude, geographical zone are also different with sun earth astronomical relation. For getting peak data and actual data is differing with weather condition and seasonal basis. It is difficult to measure correct data by conventional monitoring system. Those monitoring techniques are sometimes unable to collect required data for long time and at specific time duration. A new technique is proposed as a solution to overcome the limitations of other techniques. The proposed technique uses distributed Point to Point (P2P) communication (Ethernet), for the collection of data, with a standard supervision graph and data server. A dedicated computer server will collect actual data with distributed P2P connection and will store in server’s database view as a graph and data sheet. In order to study and evaluate the performance of proposed technique, measures actual data values. By the technique we can easily get hourly, daily, monthly and yearly performance data of a PV system.
Study on the development, implementation and validation of a design model simulated for photovoltaic water pumping systems (PVPS)
(University of Dhaka, 2016-05-04) Khan, Momotaz Mahin
In this thesis work a C++ (Programming language) Codelite, V9.0.1 Software was used to design a stand-alone Photo Voltaic Pumping System (PVPS). An algorithm was developed, which would design a stand-alone Photo Voltaic system for pumping underground water. The algorithm calculates the amount of energy required to draw the water for the specified height to give pump rating and the flow rate. The inputs required are amount of water required per day, number of autonomy days, the total dynamic height and the pump efficiency. To design the solar array the inverter voltage, single panel voltage and current (dependent on the individual panel power) is used to design the series and parallel array. The developed sizing method has been validated by applying it to one real scenario case where PVPS was already present. The obtained results was (1000 cubic meter water in 7.7 hours was pumped using 10 HP pump with 21 solar panel in series and 3 parallel arrays) have been compared with the characteristics of the real PVPS. The reliability of the design procedure has been verified, observing the similarity between the calculated out puts and the respective real values.
Performance optimization of c-Si solar cell by tuning the device parameters
(University of Dhaka, 2016-05-05) Hasan, Mirza Rakibul
The performance of a solar cell depends upon different parameters of it. To study the effect of different parameters on the efficiency, different solar cell simulation software are well practiced in the advanced semiconductor research labs to skip repeated costly and time consuming experiments. A study utilizing the PC1D solar cell simulation software shows that a crystalline silicon solar cell gives optimum performance having a very thin top n layer with total cell thickness of 80 μm, Surface texturing angle of 610, Back Surface Field (p++) of about 95×1016 cm-3 more than the p layer, Anti reflection coating of MnO2. The 86.4nm thick ARC layer with refractive index of 1.7355 showed a better internal and external quantum efficiency at the visible range of solar spectrum with around 92% EQE at 600nm light wavelength. The research reveals that overall efficiency improvement of 5.5% is possible for proper selection of dimension, electrical and optical parameters of the c-Si solar cell.
Fabrication and Performance analysis of Fe Doped TiO 2 dye sensitized solar cell 2 O 3
(University of Dhaka, 2016-05-05) Shafiul, Azam
Solar energy is a renewable free source of energy that is sustainable and totally inexhaustible, unlike fossil fuels which are finite. Solar power is clean green electricity that is either created from sunlight or from heat from the sun. Solar (or photovoltaic) cells convert the sun’s energy into electricity. Whether they’re adorning your calculator or orbiting our planet on satellites, they rely on the photoelectric effect: the ability of matter to emit electrons when a light is shone on it. As the name implies, the mechanism of dye solar cells is based on the photo electrochemical processes. This paper aims to fabricate and analyze the performance of dye sensitized solar cell by comparing the utilization of opaque TiO2 pastes and opaque TiO2 pastes with Fe2O3 doping for the photoelectrodes. Among other semiconductors, hematite (Fe2O3) is an attractive material because of its wide abundant, low cost, non-toxic nature. It is gaining importance in photoelectrochemical devices due to its suitable band gap (∼2.2 eV). It has been reported that the use of nanostructured materials in the DSSC could enhance the low energy conversion efficiency of these cells. The current-voltage (I-V) measurements were performed by using an artificial sun-simulator. As for the counter-electrode, carbon (C ) was used as the catalyst which was deposited using DC-sputtering technique. Our results revealed that the cells featuring opaqueTiO2 paste with Fe2O3 doping achieved better photoconversion efficiencies compared to that of the opaque TiO2 paste. This combination further increases its optical transmittance and band gap of the photo electrode of DSSC. The sole purpose was to optimize the characteristics of this material by focusing on its several characteristics followed by changing the duration of solution preparation, changing the deposition level on substrates, variation in annealing atmosphere and temperature to observe the characteristics changes occurred in the film. In each stage of observation significant characteristics of the film have found which the main execution of this thesis.
A case study of energy audit in a residential hall of University of Dhaka for Energy Efficiency Measures (EEM)
(University of Dhaka, 2016-05-05) Monsur, Md. Abul; Nahiyan, Abudllah Al
The buildings of Fazlul Haque Muslim Hall were selected for a detailed study of electricity consumption that is located in the University of Dhaka in 2015. Living rooms, dining hall with kitchen, provost office, mosque, laundry room, food courts and a canteen compose these buildings. The aim of this thesis is to design the best approach to reduce consumption and achieve a high efficiency of energy utilization in these buildings. The project is going to optimize the system. Series of measurements are taken to achieve the electrical energy losses. The electrical energy losses are calculated through the buildings in the first step. Afterwards, with the result of electrical usage an energy balance is made to calculate the efficiency of the installation through the buildings envelop. It is to study the indoor climate within a building, as well as energy consumption for the entire building. In addition, it is also used to measure the temperature of ventilation systems and check the schedule of air supply. Analyze the result of the value that is measured. Improve some part of these buildings that reduce the electrical energy consumption. At last to give some recommendations like identification of heat leakages at different points e.g. at faulty door and windows to reduce electrical energy loss and also identifying various obstacles in natural ventilation system of building, which eventually reduce the room temperature and make it comfortable.
Design and development of an I-V curve tracing and electrical performance analyzing system for solar photovoltaic module
(University of Dhaka, 2016-05-05) Masud, Md. Abu Sayed Siddique; Romel, Mahiuddin Mahmud
The electrical performance of a photovoltaic solar cell is described by its current–voltage (I–V) characteristic curve, which is in turn determined by device and material properties. This work presents a system capable of tracing current-voltage (I-V) characteristic curve and analyzing electrical performance characteristics of solar photovoltaic cells as well as modules. This system is divided into two main parts; firstly the current-voltage (I-V) data with temperature of the module at that instant, when it has brought under direct or diffused sun light, has been collected form the solar photovoltaic cell or module by means of some basic electronic circuits like current and voltage sensing using simple pulsed width modulation (PWM), MOSFET switching arrangement, liquid crystal display(LCD), keypad made with three selecting switch, temperature sensor, USB serial converter etc. These data has been stored in an EEPROM. Total system has a microcontroller to complete all the tasks it is programed for. Secondly the collected data transferred through an USB to TTL transfer system to the computer where it’s going to be analyzed. To analyze the data collected from the module a handy analyzer software tool has been made in Java platform with Java programming language. Where we plot graphs of I-V and P-V characteristics curve and compare the results with the given module data. Thus long-term measurements of solar PV modules electrical performances in different operating modes and in different environments become possible through this system.
Feasibility study of pellet (Saw dust and rice husk) in Bangladesh
(University of Dhaka, 2016-05-05)
This thesis concerns the feasibility of pellet (Saw dust) in Bangladesh. I describe the Biomass situation in the world as well as in Bangladesh. Pellet is one of the useable applications of Biomass. In this thesis we describe what is pellet? How to develop pellet? What are uses of pellet? and add a practical information of a pellet industry (Eco-Fuel Pellet Industry). We know Bangladesh population is increasing and the Bangladesh has needed more electrical energy. The products quantities that use up electricity have grown rapidly. Fossil fuels have been excessively consumed. The traditional energy sources mostly used in Bangladesh are diminishing at a rapid rate thus causing energy crisis all over the country. Supply of power is less than demand in insecure situation in Bangladesh. Considering all these barriers, Renewable energy is being looked at as an alternative for Bangladesh. Biomass from agriculture, especially rice husk and saw dust, is a very promising renewable energy source since it is indigenous and is considered to have environmental benefits. In this thesis, it has been put some statistical data and analysed the data reflecting the possibility of establishing power generation unit using rice husk and saw dust as a fuel.
Characterization of al-doped conductive layer of ZnO thin film solar cell
(University of Dhaka, 2016-05-08) Khan, Mohammad Shakil
Zinc Oxide (ZnO) is a group II-VI semiconductor thin film with a hexagonal wurtzite crystal structure. Its direct wide band gap of Eg= 3.2~3.7eV, low electrical resistivity, high optical transmittance characteristics within the visible range and high resistance to degradation under normal operating conditions. These characteristics distinct itself from other semiconductors with similar crystal structure to widely use in optoelectronic industries. ZnO doped with impurity is a potential choice for transparent conducting oxide (TCO) in commercial area as a transparent electrode in flat panel displays (FPDs) and solar cells. As it is regarded a good transparent conductive oxide (TCO) due to its opto-electro properties, non-toxicity, relatively abundance and low cost; Attention of this is to analyze materials thickness, surface morphology, electrical characteristics, crystal structure and orientation. In execution to this purpose, the sol-gel process of producing Zinc Oxide (ZnO) has chosen which is doped by impurities of Aluminum (Al) to make Al doped Zinc Oxide (Zno:Al) on a glass substrate, using 2-methoxyethanol as solvents and monoethanolamine (MEA) as stabilizer. This combination further increases its optical transmittance and band gap of the thin film material. The sole purpose was to optimize the characteristics of this material by focusing on its several characteristics followed by changing the duration of solution preparation, changing the deposition level on substrates, variation in annealing atmosphere and temperature to observe the characteristics changes occurred in the film. In each stage of observation significant characteristics of the film have found which the main execution of this thesis.
Design of a solar charge controller set point and lead acid battery capacity tester
(University of Dhaka, 2016-05-08) Rayhan, Tanvir; Hossain, Shahriar
This aim of this thesis is the designing of testing instrument for SHS. SHS is a growing sector in our country. In every SHS batteries and a DC charge controller are used. But capacities of those batteries or the performance of the DC charge controllers are not always verified before use. Due to that the system performance may become a problem for the consumers. These instruments can measure the capacity of a battery and sense the different set-points of a DC charge controller. From the measured data the capacity of the battery can be measured and can be decided whether it’s good enough to use in a SHS or a battery which is already being used should to be replaced according to standard specification. By sensing the set-points of a DC Charge Controller we can compare with the standard set points and decide if the Charge Controller is good enough to use in a SHS. The purpose of this project is to determine the quality of the batteries and the DC charge controllers can be measured before using it on a SHS, so the consumer can be secured from a faulty system. We have used “Arduino IDE”, open source software is used for the programming and communication interface between the computer and the data acquiring circuits. The developed systems have been in the laboratory of IE. It is found that the developed instrument works properly.
Estimation and analysis of rooftop solar PV power system in Bangladesh
(University of Dhaka, 2016-05-16) Azad, Mst. Juthika
The increasing demand of electric power and shortage of present energy resources lead today engineers and scientists to think about the alternative sources of energy, the sunlight is a potential sources for generating electric power. In recent years, it is increasingly used to generated power .The use of solar energy is attractive for rooftop solar system application also. Rooftop Solar systems are quite needing no fuel and require very little maintenance. Another advantage of PV system is: free energy, reliable power, flexibility and quick installation. The aim of this thesis is to Estimate and analysis of Rooftop Solar PV System in Bangladesh and to be a participant to make Bangladesh the first Solar Nation. Here discussed about solar photovoltaic system in Bangladesh both solar home system and rooftop solar power system. Broadly discussed about Rooftop solar power pv system. It’s connection, it’s metering arrangements etc. The important part of the thesis is to estimate the total installed capacity in rooftop pv system in Bangladesh without considering limitations and with considering limitations. At last to give some idea to calculate the installed capacity properly like site assessment, shading analysis, Financing Options, Legal and Regulatory Frameworks etc.
Estimation of the output power of east and west facing pv panel and comparison with south facing pv panel
(University of Dhaka, 2016-10-13) Paul, Rupak; Hasan, Md. Hasibul
In this work, a typical east -west facing solar system has been designed to study the daily and hourly solar radiation of this system and to compare it with a south facing solar system. This study shows that an east-west facing solar panel gives comparatively lower radiation than a south facing solar panel. But the amount of that radiation is significant. Bangladesh is a populated country where price of land is so high. Sometimes it is not possible to set up a solar panel at south facing due to infrastructure limitations. So setting up an east-west solar panel instead of or beside a south facing solar panel could run a solar system more effectively. Using this type of solar system at top of couple roof house will be count as an innovative technology for those who are not able to set up a solar system due to infrastructure limitations. Beside this, an east-west solar system could add extra output with existing solar system and will utilize the limited solar radiation at small area significantly.
Design, development and performance analysis of a new desalination system integrated with a low cost fabric absorber
(University of Dhaka, 2016-11-13) Reza, S.M. Shamim
In the coastal region of Bangladesh salinity in water pose a serious problem. The chief difficulty in the development of appropriate water supply system for the communities in the affected area is that - deep aquifers containing sweet water are not found at all possible locations in the coastal region. [1] There is various desalination techniques- practiced all over the world but the conventional desalination process is energy intensive and will be an expensive option particularly in the rural area of Bangladesh. Solar energy on the other hand is freely available in nature in sufficient amount. Moreover, the technology involved in distillation of saline water using the solar energy is relatively simple and maintenance can be carried out by semi-skilled or unskilled operators. Therefore, in this study, an attempt has been made to develop a family size solar desalination plant with using the black cotton fabric and produce desalinated water from vapor which meets the drinking water demand in the coastal area and remote regions. In this system direct sunlight has been utilized long back for desalination of water. Solar stills are easy to construct, can be done by local people from locally available materials, simple in operation by unskilled personnel, no hard maintenance requirements and almost no operation cost. But they have the disadvantages of high initial cost, large land requirement for installation and have output dependent on the available solar radiation. In this paper presents the experimental and theoretical work, conducted to analyses the performance of modified basin type solar still, incorporating multiple low thermal inertia porous absorbers. The porous absorbers were made up of ordinary fabric (woven or nonwoven). The absorbers ensured that the absorber surface was always wet due to capillary action and there were no dry spots. Due to low thermal inertia of the porous absorber, quicker start-up times, as well as higher operating temperatures were achieved resulting in higher distillate yield. Also, the increase in the evaporation surface area further aided the performance. In order to evaluate the improvement obtained by the modification, the performance of the modified still was compared with a conventional basin type solar still of same size, under similar operating conditions on both clear and partially clear days. The results indicate that on clear days more distillate output was obtained by the modified still, whereas it was nearly more on cloudy days.
Fabrication of a dye sensitized solar cell using blackberry dye: Effect of TiCl 4 as blocking layer
(University of Dhaka, 2016-11-13) Qazi, Masrura
Energy crisis is one of the most pressing issues of the world. Increasing industries and luxuries have made energy limited compared to the demand for it and the reserve in fossil fuel. An alternative to this crisis is the inorganic and organic solar cell. Organic solar cell having a cost effective prospective is highly demanding. During this research work, a prototype of dye-sensitized solar cell was developed using organic dye from blackberry and TiO2 nanocrystals paste was used as semiconductor. All work was done in the dye-sensitized solar cell lab of Bangladesh Atomic Energy Commission in joint collaboration with University of Dhaka. The TiO2 and the ITO glasses were imported while the dye was obtained locally. The developed cell was tested for measurement of efficiency in a lab-constructed simulator where the irradiation was provided with a halogen lamp of 20 Watt/220 Volt with intensity of around 900 W/m2 at a distance of 30cm. The characterization of the cell gives I-V characteristics with open circuit voltage of 440 mV, short circuit current of 600μA, fill factor of 45.67 %, and energy efficiency of 0.03 % for raw dye. An improved cell current and cell-voltage was observed when the dye was extracted by soaking in ethanol, for which the characterization of the cell gives I-V characteristics with open circuit voltage of 497mV, short circuit current of 943μA, fill factor of 40.61 %, and energy efficiency of 0.05 %. However it was found with more improved cell efficiency when post treatment was performed on the titanium dioxide layer; the improved cell efficiency being 0.0869%. The solar cell shows degradation in performance with open circuit voltage and short circuit current degrading gradually.
Design optimization of a-Si:H p-i-n, c-Si:H p-i-n, and micromorph tandem PV cell
(University of Dhaka, 2016-11-13) Sarkar, Nazmul Islam
The performance of a solar cell depends on different design parameters like its doping concentration, layer thicknesses, bandgaps, etc. To ameliorate the solar cell performance studies are done on the effects of different device parameters on its efficiency and others using different solar cell simulation software to skip repeated costly and time consuming experiments in advanced semiconductor labs. In this research, studies on numerical design and performance optimization of a single junction hydrogenated amorphous (a- Si:H) p-i-n cell, hydrogenated single junction microcrystalline ( c-Si:H) p-i-n cell, and micromorph tandem solar cell have been carried out using well-practiced AFORS-HET software. The analyses show that short circuit current density, open circuit voltages, maximum fill factors and the efficiency for the above three configurations cell can be achieved in the range of 10.77 mA/cm2 to 33 mA/cm2, 906.5 mV to 1442 mV, 68.9% to 85.3% and 13.26% to 20.78% respectively. These numerically designed cells can perform very well in high frequency spectrum. For lights of 300 to 500 nm wavelengths the external quantum efficiencies (EQE) of micromorph tandem structure and a-Si:H p-i-n cell have high but for 600 to 800 nm wavelengths, its value is low. On the other side for the lower wavelength spectrum the EQE of c-Si p-i-n is low, but comparatively higher than that of conventional c-Si cell and high for upper wavelength spectrum. The results for short circuit current density of 33 mA/cm2, open circuit voltage of 906.5 mV, fill factor of 69.4% and efficiency of 20.78% of a hydrogenated single junction microcrystalline ( c- Si:H) p-i-n cell solar cell reveals that it is best and would emulate the performance of other structures shortly.
Techno-economic analysis of biomass waste based pellet production in Bangladesh
(University of Dhaka, 2016-11-13) Al-Saiem, Asad Dullah
his thesis involves with the techno- economic analysis of biomass waste pellet production in Bangladesh. As an agricultural country along with a larger population we have lots of biomass waste. 75% of energy comes from biomass in rural area we found that agricultural waste and residues are used in a non-efficient and non-hygienic way. Mainly this energy consumption is happened in rural indigenous cooking system with only 8-12% efficiency. The main problem with that biomass is less density and moisture content. By palletizing we can solve those problems. In this thesis, it has been put some statistical data and analysed the data reflecting the possibility of establishing power generation unit using biomass waste pellet.we also introduced a new raw material mix, caddies with saw dust. Our test production was successful. We tested our experimental pellet and found very suitable as a fuel with calorific value 4235.4 kcal/kg and density index 0.96. The pellet production also found economically feasible. By using pellet we can solve our energy crisis, assuring hygiene in rural cooking and save the entire environment.
Assessment of different topological integration of solar power plants in medium voltage distribution networks
(University of Dhaka, 2016-11-13) Rahman, Mushfiqur; Hossain, Md. Tanzid Ridwan
Storage of fossil fuels is limited. Burning of fossil fuels for electricity generation, transportation, heating, cooking, industrial production and other purposes cause emission of gases and other particles, which are harmful for environment. Emission of green hose gases causes global temperature increase. Sunlight is abundantly available than fossil fuels. Photovoltaic (PV) power plants are better than fossil fuel based plants in terms of environmental impact. To make and photovoltaic based plant efficient and cheaper it is important to integrate these systems into distribution systems properly. In this paper, an analysis of placement of photovoltaic system in different uses of medium voltage (MV) a distribution system has been done. Loadability, voltage levels, maximum power input has been analyzed. A comparative study has been carried out about fractioning effect of photovoltaic generator in distribution system. Results and analysis show that change in loadability due to placement and fraction of solar plant in different buses. Maximum input level of photovoltaic system varies with placement among different buses. Interaction among photovoltaic system, induction machine, dc machine and synchronous machine has been also carried out. Results found from this analysis show that interaction among photovoltaic system, induction machine, dc machine and synchronous machine were different in terms of loadability and voltage level. Fractioning of machines has also different impact on bus voltage level and loadability of system. Change in bus voltage level is occurred due to placement of photovoltaic system at different buses. Effect of integration of photovoltaic system into extra buses extended from different buses and effect of distribution of generation unit and fractioning were analyzed. Result has been found that change in loadability occurred due to fractioning and distributing of photovoltaic system on different types of design topology of system.
Fabrication and characterization of ZNS buffer layer for thin film solar cell using chemical bath deposition (CBD) method
(University of Dhaka, 2016-11-13) Sharfuddin, Md.
Zinc sulfide thin films were prepared by chemical bath deposition technique using zinc sulfate (ZnSO 4 .7H 2 O) and thiourea [SC(NH 2 ) 2 ] as sources of Zn 2+ and S ions, and ammonia (NH 3 ) and hydrazine hydrate (N 2 H ) as complexing agents. ZnS is an important semiconductor compound of excellent physical properties such as wide band-gap energy of 3.7 eV at 300 K, high refractive index (2.35 at 632 nm), transparent to practically all wavelengths of the solar spectrum, non-toxic and environmentally friendly buffer materials that are suitable for industrial production. A very attractive method for producing ZnS thin films, due to the possibility of large-area deposition at low cost is the chemical bath deposition (CBD) method. Chemical bath deposition (CBD) is known to produce solar cell grade films at simpleness, convenience, a low cost and low temperature. The depositions were carried out by varying PH of bath solution from 9.3 to 10.1 and keeping bath temperature fixed at 70 °C for two hours. The thickness of the films was tuned between 72 nm to 319 nm by controlling the ammonia and thiourea concentration. The structural, stoichiometric proportion, morphology and optical properties of the ZnS thin films were investigated as a function of thiourea and ammonia concentrations using X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and UV- visible spectro-photometry measurements. X-ray diffraction analysis of the as-deposited films showed that the films have amorphous structure and poor crystallinity. Energydispersive spectroscopy (EDS) showed that all ZnS thin films exhibited both Zn and S. The UV–visible spectrophotometric measurement showed that, the transmittance of the ZnS thin films vary from 45% to 65%, while the band gap vary from 3.85 eV to 3.89 eV for different ammonia and thiourea concentration.
Mathematical modeling of shading by obstacles and prediction of optimal energy generation from a solar pv system per unit area over the year
(University of Dhaka, 2016-11-16) Siddique, Shah Mohammad Mohiuddin
There is an exponential growth and growing popularity of solar photovoltaic technology for energy generation in comparison with the conventional and other renewable energy sources. But the massive utilization of this technology is hindered by space constraints. And that is why optimal use of space with solar PV modules is a pre-requisite for optimal energy generation per unit area. In this research, the sunpath diagram, surrounding obstacles shading, optimal PV module row spacing have been analyzed and a mathematical model have been developed which is solved using Mat lab. This study shows that the optimal module row spacing is about 1 meter considering comparatively effective sunshine hour (9:00am to 3:00pm) for commercial systems. The minimum module row spacing calculated from sun-path diagram is about 1 meter under the same condition. Deviation between the values of module row spacing calculated from these two method is only 1.05%. Power generation per unit area by minimum module row spacing calculated from our proposed model is about 250 kWh per square meter land area. Return rate of money due to the use of minimum row spacing is about 20%. Moreover in this research a shading diagram has been proposed to study the effect of obstacles over the year on a solar system drawn by the overlaying of horizontal-profile over sun-path diagram which will provide information about which obstacles may cause shading at a specific time of day and year. It can be analyzed from the shading diagram that which obstacle may affect by shading at specific time over the year. The mathematical model is solved by Mat lab.