Luận án tiến sĩ nghiên cứu ảnh hưởng của môi trường nhiệt đới angola tới hoạt động và một số giải pháp công nghệ

CONTENTS CONTENTS i LIST OF SYMBOLS iv LIST OF ABBREVIATIONS .vi LIST OF FIGURE viii LIST OF TABLES xii INTRODUCTION CHAPTER LITERATURE REVIEW 1.1 Overview of renewable energy use in the World 1.2 Overview of solar cell use in the Angola - 1.3 The photovoltaic effect 1.4 Physics of Solar Cells 11 1.5 Overview of Silicon Solar Cell Technologies -17 How does PERC technology improve performance? 20 1.6 Influence of tropical climate in the performance of PV panels 21 1.6.1 Spectrum -22 1.6.2 Irradiance 22 1.6.3 Module temperature 23 1.6.4 Wind speed 23 1.6.5 Incident angle 23 1.6.6 Effect of humidity on the solar panels -24 1.6.7 Effect of dust on the solar panels -25 CHAPTER THE INFLUENCE OF ANGOLA TROPICAL CLIMATIC CONDITION ON THE PV SYSTEM PERFORMANCE 27 2.1 Experimental introduction -27 2.2 Influence of Solar radiation 29 2.3 Influence of Temperature 32 2.4 Influence of humidity 37 2.5 Effect of radiation on PV characteristics 40 2.6 Effect of an inverter 42 2.7 Effect of wind actions on PV panels -42 2.7.1 General -42 i 2.7.2 Computational Fluid Dynamics (CFD) Procedure -47 2.7.3 Effect of wind actions on solar panels -51 Chapter summary 67 CHAPTER STUDY ON TITANIUM DIOXIDE APPLICATION AS SOLAR CELL SELF-CLEANING LAYER 68 3.1 Settlement overview of dust on a solar panels glass cover 68 3.2 Thin film TiO2 using as self cleaning material of solar panels 69 3.2.1 The self-cleaning properties -69 3.2.2 Theoretical basis of self-cleaning -69 3.2.2 1.Young’s equation -70 3.2.2.2 Cassie model 70 3.2.2.3 Wenzel model -71 3.2.2.4 Cassie and Baxter’s Equation -71 3.2.3 Thin film TiO2 using as self-cleaning material -72 3.3 Nanocrystalline TiO2 thin film deposited by spray pyrolysis technique and sol gel –hydrothermal method 73 3.3.1 Experiment details 74 3.3.2 Characterizing of TiO2pure and doped iron or tungsten thin film 77 3.3.2.2 Characterizing of Fe-dopedTiO2 thin film -81 3.3.2.3 Characterizing of W-dopedTiO2 thin films 84 3.3.3 Self-cleaning properties of TiO2pure and doped iron or tungsten thin film 88 Chapter conclusion -93 CHAPTER GROWTH AND CHARACTERIZATION OF Al2O3 ULTRATHIN FILM AS A PASSIVATION LAYER FOR SILICON SOLAR CELLS 95 4.1 The need for silicon solar cells passivation layer Al2O3 -95 4.2 Carrier Recombination in Crystalline Silicon -96 4.3 Surface passivation 98 4.4 Surface passivation materials 100 4.4.1 Silicon dioxide SiO2 101 4.4.2 Hydrogenated amorphous silicon nitride a-SiNx:H 101 4.4.3 Hydrogenated amorphous silicon a-Si:H 101 4.4.4 Aluminum oxide Al2O3 102 ii 4.5 Growth Al2O3 ultra-thin film by Atomic Layer Deposition - 102 4.5.1 Introduction ALD technique - 102 4.5.2 Growth process of thin film aluminum oxide by ALD 104 4.5.3 Process for p-type Si solar cells(PERC) fabricated - 105 4.5.4 The investigated method - 107 CONCLUSION - 118 The scientific and practical significance of the thesis - 119 Recommendations for Future Studies - 120 REFERENCES Error! Bookmark not defined iii LIST OF SYMBOLS Number Symbol Name A Quality factor C The specific heat capacity (J/K.kg) CF The force coefficient Cp The pressure coefficient D Average crystallite size E Energy e Electron EA Ionization energy EC Conduction band energy 10 EF Fermi energy 11 Eg Optical band gap energy 12 EV Valence band energy 13 F The force applied on the surface 14 ff fill factor 15 h Hole 16 J Current density 17 Jmax Current density at maximum power output 18 JSC Short circuit current density 19 m Mass (kg) of the material 20 Pmean 21 Q Quantity of heat (Joules) 22 R0 Initial resistance (Ω) 23 R Resistance between the contacts 24 RS Serial resistance 25 Rsh Shunt resistance 26 Rsheet Sheet resistance 27 t Time 28 T Transmittance 29 TA Absolute temperature 30 TC Calcined temperature The mean pressure iv 31 Te Environmental temperature 32 TS Substrate temperature 33 V Voltage 34 Vmax Voltage at maximum power output 35 VOC Open circuit voltage 36  Absorption coefficient 37  Thickness 38  Conversion efficiency of the solar cell 39 λ Wavelength 40 λex Excitation wavelength 41 e Electron mobility 42 p Hole mobility 43 ρ0 Initial resistivity (Ωm) 44  Resistivity 45 eff Effective lifetime 46 rad Carrier lifetime due to radioactive recombination 47 Auger Carrier lifetime due to band to band i.e Auger recombination 48 SRH Carrier lifetime due to defects i.e SRH recombination 49 Surf Carrier lifetime due to surface recombination v LIST OF ABBREVIATIONS Number Symbol Name AFM Atomic Force Microscope ALD Atom layer deposited APE Average photon energy CFD Computational fluid dynamics CVD Chemical vapour deposition DRE Department of Renewable Energy ECCP Energy Pool of Central Africa- EDX Energy Dispersive X-ray ETA Extremely thin absorber 10 FESEM 11 FTO 12 FWHM Full width at half maximum 13 IEA International Energy Agency 14 LED Light Emitting Diode 15 MB Methylene blue 16 MINEA Ministry of Energy and Water 17 MPPT maximum power point tracking 18 PV Photovoltaic 19 PCE power conversion efficiency 20 PDA Post deposition annealing 21 PECVD 22 PERC Passivized emitter and rear cell 23 PERL Passivized emitter and rear locally diffused cells 24 PMT Solar cells 25 PO Field Emission Scanning Electron Microscope Tin oxide doped Fluorine Plasmaenhanced chemical vapor deposition Power output vi 26 SHS Solar home system 27 SAPP Southern African Power Pool 28 SEM Scanning Electron Microscope 29 SPD Spray Pyolysis Deposition 30 STC Standard test conditions 31 TCO Transparent conducting oxide 32 TMA Trimethyl Aluminum 33 TTIP Titanium tetraisopropoxide 34 USPD Ultrasonic Spray Pyolysis Deposition 35 UV-VIS 36 VASE 37 XPS X-ray photoemission spectroscopy 38 XRD X-ray diffraction UV-VIS Spectrophotometer Variable-angle spectroscopic ellipsometer vii LIST OF FIGURE Figure 1.1 Price comparison of energy sources [5] Figure PV module price over time [14] Figure 1.3 Graph illustration absorption of a photon in a semiconductor with an Eg band gap [16] 10 Figure 1.4 Component parts of a typical PV cell 11 Figure 1.5 Graph illustration structure of a 1D p-n homogeneous solar cell 12 Figure 1.6 Ideal short-circuit current density of p-n junction solar cell as a function of Eg [22] 14 Figure 1.7 J- V curves of a solar cell in the dark and under illuminated condition [17] 15 Figure 1.8 Graph illustration equivalent circuit of a real solar cell [17] 15 Figure 1.9.Graph of p–n junction solar cell factor as a function of band gap 16 Figure 1.10 Market share of PV cells (%) [26] 17 Figure 1.11 Scheme of a modern crystalline silicon cell [29] 18 Figure 1.12 Imaging of Poly‐crystalline Si cell (a), and Mono-crystalline Si cell (b) [19] 20 Figure 1.13 The structure of a conventional cell (a) and the structure of a cell with PERC technology (b) [17] 20 Figure 1.14 A cell with PERC technology will generate more current due to the reflection of light at the backside of the cell 21 Figure Average monthly insolation levels in Luanda 27 Figure 2 Diagram of collecting and monitoring data of operating solar panels 28 Figure Kipp & Zonen’s Pyranometer Model CMP6, ISSO 9060 / WMO First Class Standard: (a) Solarimeters measurement system; (b) The anemometer 28 Figure The software for collect data 29 Figure The solar irradiance intensity through the experimental day in day 29 Figure Maximum output power versus solar radiation 30 Figure The PCE versus solar radiation 30 Figure The open circuit voltage Voc(a) and the short circuit current Isc (b) with varying solar radiation 31 Figure 2.9 The ambient temperature and modules temperature on time in day 33 Figure 2.10 Average panel temperature versus ambient temperature 34 Figure 2.11 Open circuit voltage (a) and Short circuit current (b) versus ambient temperatures 35 Figure 2.12 The conversion efficiency versus ambient temperature 37 Figure 2.13 Maximum power output versus wind speed 37 Figure 2.14 The relationship between open circuit voltage and relative humidity 38 Figure 15 The relationship between short circuit current and relative humidity 38 Figure 2.16 The relationship between relative humidity and ambient temperature 39 Figure 17 The relationship between relative humidity and PV efficiency 39 viii Figure 18 Equivalent circuit for amorphous solar cell The current sink Irec stands for recombination losses in i-layer 40 Figure 2.19 Current-Voltage characteristics of PV cells before and after projecting by neutrons with different illumination dose :1-=0; 2- =6*108; 3-=1.2*109; 4-=1.8*109; and 5-=2.4*109 41 Figure 2.20 Comparison of power converted by inverter (Pac) and power produced by PV system (Pmax) 42 Figure 21 Location of the application point of the global wind force acting on monopitch canopies (SR EN 1991-1-4/2006) 44 Figure 22 Scheme of a free standing panel in the air flow (a, c [81]); (b) the resulting movement due to flow separation [82] 44 Figure 23 Illustration of lift and draft forces 45 Figure 2.24 Wind speed (km/h) in Luanda shows days per month 46 Figure 25 Solar panels placed at ground level 47 Figure 2.26 Generated model of solar panels(a) Support and (b) Support with solar panels 48 Figure 2.27 Computational domain 49 Figure 2.28 Mesh of computational domain 49 Figure 2.29 Mesh of computational domain 50 Figure 30 Distribution of pressure and streamline of fluid flow around solar panels at centered XY plan – Wind velocity 3m/s & Attack angle 0o 51 Figure 31 Distribution of pressure and streamline of fluid flow around solar panels at centered YZ plan – Wind velocity 3m/s & Attack angle 0o 52 Figure 2.32 Distribution of pressure and streamline of fluid flow around solar panels at centered XZ plan – Wind velocity 3m/s & Attack angle 0o 53 Figure 2.33 Distribution of pressure on solar panels – Wind velocity 3m/s & Attack angle 0o 54 Figure 2.34 Effect of inclined angle of PV to aerodynamic characteristics - Wind velocity 3m/s & Attack angle 0o: a) Coefficient of lift and drag force and b) Aerodynamic quality 55 Figure 35 Distribution of pressure and streamline of fluid flow around solar panels at centered XY plan – Inclined angle 30o& Attack angle 0o 56 Figure 36 Distribution of pressure and streamline of fluid flow around solar panels at centered YZ plan – Inclined angle 30o& Attack angle 0o 57 Figure 37 Distribution of pressure and streamline of fluid flow around solar panels at centered XZ plan – Inclined angle 30o& Attack angle 0o 58 Figure 38 Distribution of pressure on solar panels – Inclined angle 30o& Attack angle 0o 59 Figure 39 Effect of inclined angle of PV to aerodynamic characteristics - Inclined angle 30o, Attack angle 0o: a) Coefficient of lift and drag force and b) Aerodynamic quality 60 Figure 40 Distribution of pressure and streamline of fluid flow around solar panels at centered XY plan – Wind velocity 9m/s & Inclined angle 30o 61 Figure 41 Distribution of pressure and streamline of fluid flow around solar panels at centered YZ plan – Wind velocity 9m/s & Inclined angle 30o 62 Figure 2.42 Distribution of pressure and streamline of fluid flow around solar panels at centered XZ plan – Wind velocity 9m/s & Inclined angle 30o 63 ix Figure 2.43 Distribution of pressure on solar panels – Wind velocity 9m/s & Inclined angle 30o 64 Figure 2.44 Effect of inclined angle of PV to aerodynamic characteristics - Wind velocity 9m/inclined angle 30o: a) Coefficient of lift and drag force and b) Aerodynamic quality 65 Figure 2.45 Mesh of strength analysis problem: a) Without solar panels and b) With solar panels 66 Figure 2.46 Total deformation - Wind velocity 9m/s; Attack angle 0o& Inclined angle 30: 66 Figure 2.47 Equivalent Stress - Wind velocity 9m/s; Attack angle 0o& Inclined angle 30o: 66 Figure 1.Contact angle platform 70 Figure 3.2 Wetting on flat and rough surfaces: (a) flat, (b) rough, Wenzel case; (c) Cassie and Baxter case 71 Figure 3.3 Type two self-cleaning mechanism exists of TiO2 thin films 72 Figure 3.4.The pyrolysis system at SEP, HUST 75 Figure 3.5 Raman spectra of the TiO2 films deposited at substrate temperatures 78 Figure 6.FESEM images of TiO2 films deposited at: a) 4000C; b) 4500C 78 Figure 3.7 AFM image of TiO films deposited at substrate temperatures: a) 400; b) 450 and c)5000C 79 Figure 8.The optical transmission spectra of TiO2 films deposited at substrate temperatures 80 Figure 3.9 The plots of (αh)2 versus h for optical band gap the calculation of TiO2 films deposited at substrate temperatures 80 Figure 3.10.XRD patterns of the F0, F15, F35, F55 and F75 samples 82 Figure 3.11 FESEM images of the Fe doped TiO2 thin films: (a) F15; (b) F35; (c) F55 (d) F75 83 Figure 3.12 Transmittance spectra of Fe doped TiO2 thin films: (a) F0; (b) F15; (c) F35; (d) F55 (e) F75 83 Figure 3.13 Plot of the band-gap and Fe3+ concentration of the doped samples 84 Figure 14.XRD patterns of the W doped TiO2 thin films: (a) W0; (b) W1; (b) W2 and(d) W5 85 Figure 3.15 Raman spectra of W doped TiO2 thin films: (a) W0; (b) W1; (b) W2 and(d) W5 85 Figure 3.16 SEM image of a) TiO2 thin film and b) its cross sectional 86 Figure 3.17 SEM images of W doped TiO2 thin films (a) W0; (b) W1; (b) W2 and(d) W5 86 Figure 3.18 Transmittance spectra of W doped TiO2 thin films: (a) W0; (b) W450; (c) W1; (d) W2 (e) W5 87 Figure 3.19 The plot of (h)2 vs hfor the W doped TiO2 thin films: (a) W0; (b) W450; (c) W1; (d) W2 (e) W5 87 Figure 3.20 Photocatalytic degradation rate of MB in the presence of samples 88 Figure 3.21 Linear transform ln(C0/C) = f(t) of the kinetic curves of MB degradation of TiO2 90 Figure 3.22 Photocatalytic degradation rate of MB in the presence of TiO2 91 Figure 3.23 Linear transform ln(C0/C) = f(t) of the kinetic curves of MB degradation of W doped TiO2 thin films: (a) W0; (b) W1; (b) W2and (d) W5 under visible light irradiation 92 Figure 24 Images observed superhydrophilic ability of samples 93 Figure 3.25 Images observed superhydrophilic ability of samples under visible light irradiation 93 x increasing thickness, the value seems to saturate at about 658mV For 11nm of thickness, the maximum implied Voc, 659.1 mV, was obtained after PDA 660 Voc, (mV) 658 656 654 652 Avg.Voc Best.Voc 650 10 12 14 16 Al2O3 film thickness, (nm) Figure 13 The plots effective Voc as a function of Al2O3 film thickness 20.8 20.7 20.6 cell, (%) 20.5 20.4 20.3 Avg.cell Best.cell 20.2 20.1 10 12 14 16 Al2O3 film thickness, (nm) Figure 14 The plots effective efficiency as a function of Al2O3 film thickness Figure 4.14 shows the plots effective efficiency as a function of Al2O3 film thickness It can see that, the efficiency is the best about 20.55% when the Al2O3 film thickness is about 11nm To activate the passivation performance, a series of post deposition annealing (PDA) at different temperatures for different thickness were carried out 115 Effective minority lifetime, (s) 290 280 270 260 250 5nm 10nm 15nm 20nm 240 540 570 600 630 660 Annealing temperature, (oC) Figure 15 The plots effective Effective minority lifetime as a function of annealing temperature Fig 4.15 shows the effective minority carrier lifetime of p-type c-Si wafers passivated by 5, 10, 15 and 20 nm Al2O3 For original c-Si wafer, the eff was measured to be  ms After depositing a 20 nm-thick Al2O3 layers, a higher eff of  900 ms is obtained The results show that the effective minority carrier lifetime is improved when the Al2O3 thin films is deposited on c-Si surface To study the full potential and the thermal stability of the surface passivation performances of Al2O3 layers, the lifetime samples were exposed to PDA at temperature (Ta) ranging from 530 to 670 oC with PDA time of in nitrogen enviromental The effective minority carrier lifetime increasing with increasing PDA of Al2O3 films and begin reduction at PDA about 600oC The effective minority carrier lifetime is maximium value about 288.3µs at PDA about 600oC and 20nm of thickness Al2O3 The different thickness of Al2O3 thin films, effective minority carrier lifetime was effected The blisters gas can be have before PDA,due to make reduction of effective minority carrier lifetime Morphology of Al2O3 thin films before PDA and after PDA illutration in figure 4.16 Figure 16 Morphology of Al2O3 thin films before PDA and after PDA Chapter summary In this Chapter, the Al2O3 ultra-thin films have been grown by ALD technique The ALD process offers highly conformal films with controlled thicknesses in the monolayer level The properties of aluminum oxide (Al2O3) films have shown excellent performances such as remarkable passivation behaviors on Si surfaces This study explores the conditions necessary for low temperature fabrication of Al2O3 thin films by the ALD technique 116 The Al2O3 ultra-thin films have been grown by ALD technique Trimethyl aluminum (TMA) Al(CH3)3, and water have been used as the metal and oxygen precursors Thicknesses of the films were investigated depending on deposition cycles The estimated deposition growth rate was 1.0 Å/cycle at deposition temperature of about 200oC The Al2O3 ultra-thin films have refractive index n = 1.6 ÷ 1.75 in visible light The carrier lifetime depends on thickness of Al2O3 ultra-thin films The best valuable is about eff ~ 700 µs with thickness is about 11nm If used post-deposition annealing (PDA), the carrier lifetime iseff ~ 770 µs after PDA with thickness is about 11nm the efficiency is the best about 20.55% when the Al2O3film thickness is about 11nm.This result clearly showed the improved passivation performance of the ultrathin ALDAl2O3 films This study topics ranging from the fundamental mechanisms that govern the properties of nanolayer surface passivation schemes to the industrial feasibility of the technology For fabrication of Al2O3 one can use a cost-saving deposition technique called atomic layer deposition (ALD) The Al2O3 ultra-thin films can be used as a passivation layer to improve performance of Silicon based solar cells 117 CONCLUSION Experimented on the effects of climatic conditions in the Luanda, Angola on PV modules for a year was investigated The weather parameters were studied as the intensity of sunlight, ambient temperature, humidity and wind speed in outdoor conditions The investigation results show that: (i) Open circuit, short circuit current and performance of the c-Si solar cell system are linearly dependent on the illumination intensity (ii) As the ambient temperature rises, the temperature of the c-Si solar cell system increases, resulting in a reduction in the efficiency of the solar cell system Experimental results show that when the ambient temperature rises by about 1o, the temperature of the c-Si solar cell system increases by nearly 10o (iii) The humidity of the air also significantly influences the operation of the c-Si solar cell system Experimental results show that when the relative humidity of the environment increases from 60% to 85%, the efficiency of the PV decreases by 2.4% Humidity and wind also seemed to have an effect, but variations in humidity had a closely linked and relationship with temperature that makes it difficult to judge the true impact of humidity on performance The effect of wind as velocity, inclined angle, of solar panels to the solar cell system in Angola through the using the Computational Fluid Dynamic (CFD) software ANSYS Fluent was investigated The simulated results shown that: (i) The inclined angle of solar panels β = 30o within velocity of wind 9m/s and horizontal wind direction (attack angle α equal zero degree) is the best choice of system (ii) The lower left corner in the direction of the wind is the largest distortion of about 0.685 mm (iii) The equivalent stress is found maximum at vertical bar of support of solar panel The maximum value is about 7.46 × 104 Pa This value is lower than the limit stress of aluminum alloy (7.1 × 109 Pa) We have successfully deposited transparent TiO2 thin films using TiAcAc precursor by employing a simple and inexpensive spray pyrolysis technique The optical transmission spectra have a relatively high percentage of transmittance in the wavelength range from 400 to 900 nm The optical band gap is of the order of 3.32 ÷ 3.43 eV Fe doped- TiO2 thin film deposited by USPD: (i) Fe-doped TiO2 thin film formed anatase phase and tetragonal structure Crystal size is about 15 ÷ 25 nm (ii) Fe-doped TiO2 thin film have a relatively high percentage of transmittance in the wavelength range  = 400 ÷ 900 nm and optical band gap is Eg = 3.32 ÷ 3.43 eV (iii) Fe-doped TiO2 film have activity Photocatalytic on stain organic in visible light and the first-order reaction kinetics With 1.5% Fe-doped TiO2 sample have the best activity Photocatalytic with value kapp = 0.016 min-1 W-doped TiO2 thin film deposited by sol-gel mix hydrothermal method: (i) W-doped TiO2 thin film formed anatase phase and tetragonal structure Wolfram formed with structure WO3 118 (ii) W-doped TiO2 thin films have thickness about 1.30 ữ 1.50 àm Crystal size is about 15 ÷ 25 nm High transmittance and optical band gap are about Eg = 3.6 ÷ 3.5 eV (iii) W-doped TiO2 thin films have activity Photocatalytic on stain organic in visible light and the first-order reaction kinetics With 2% W-doped TiO2 sample have the best activity Photocatalytic with value kapp = 0.14 min-1 Fe, W-doped TiO2 thin film have high transmittance and the good activity self-cleaning in visible light These samples can be applied for self-cleaning layer in thin film solar cells The Al2O3 ultra-thin films have been grown by ALD technique Trimethyl Aluminum (TMA) Al(CH3)3, and water have been used as the metal and oxygen precursors: (i) Thicknesses of the films were investigated depending on deposition cycles The estimated deposition growth rate was 1.0 Å/cycle at deposition temperature of about 200oC The Al2O3 ultra-thin films have refractive index n = 1.6 ÷ 1.75 in visible light (ii) The carrier lifetime depends on thickness of Al2O3 ultra-thin films The best valuable is about eff ~ 700 µs with thickness is about 11nm If used post-deposition annealing (PDA), the carrier lifetime is eff ~ 770 µs after PDA with thickness is about 11 nm the efficiency is the best about 20.55% when the Al2O3 film thickness is about 11 nm This result clearly showed the improved passivation performance of the ultrathin ALD- Al2O3 films The scientific and practical significance of the thesis We are analyzing the influence of Angolan tropical climate on performance of small scale, grid connected, silicon-based photovoltaic system located in Luanda, Angola By analyzing the effects of different variables that affected the performance of Silicon PV system located in an African tropical environment, it was observed that solar irradiance had the greatest impact on performance This implies that the unexpected factor such as dust accumulation will probably have a significant impact on the performance of the system by reducing the amount of sunlight that the PV panels are exposed to The calculated results using ANSYS Fluent software show that, inclination of panels has the largest effect on the wind loads acting on solar panels Small changes in panel inclination are observed to result in significant changes in wind loads We have successfully deposited transparent TiO2 thin films using TiAcAc precursor by employing a simple and inexpensive spray pyrolysis and sol-gel-hydrothermal techniques TiO2 composite films are essential for application as a self-cleaning surface in solar panels area, when transparency and low water contact angles are required Study and investigate the effect of ALD technology parameters on the formation of Al 2O3 thin films applied as passive layer of c-Si solar cell: Study the conditions necessary for low temperature deposition of Al2O3 thin films by the ALD technique and examines properties of the resulting films This study topics ranging from the fundamental mechanisms that govern the properties of nanolayer surface passivation schemes to the industrial feasibility of the technology For fabrication of Al2O3, one can use a cost-saving deposition technique called atomic layer deposition (ALD) The Al2O3 ultra-thin films can be used as a passivation layer to improve performance of Silicon based solar cells 119 Recommendations for Future Studies Optimization studies on wind loads acting on the panels and the supporting structures in terms of solar panel inclination, spacing factor and length of panel as variable parameters is worthy to investigate Optimization of these parameters is attained through maximization of energy production from a solar farm depending on the latitude of the location on earth While the cost of the structural supporting system does not constitute the major cost compared to the cost of photovoltaic panels, the percentage of the cost due to the supporting system use and construction may be further reduced while still preserving the maximum energy output from that solar farm The study and understanding of Al2O3 surface passivation schemes in conjunction with the new ways of investigating, controlling and manipulating their properties, as outlined in this thesis, are important for the ongoing developments in the field of photovoltaic aiming at higher efficiencies and lower costs 120 THE LIST OF PUBLICATION 1) Mateus Manuel Neto, Pham Van Thang, Luu Thi Lan Anh, Pham Phi Hung, Nguyen Ngoc Trung and Vo Thach Son, Simulation investigation of wind effect on solar panels (Accepted in Journal of Science and Technology) 2) Mateus Manuel Neto, Luu Thi Lan Anh, Nguyen Trung Do, Nguyen Hoang Thoan, Nguyen Ngoc Trung, Chung Han Wu, and Vo Thach Son, Growth and characterization of Al2O3 ultra-thin film as a passivation layer for silicon solar cells., Journal of Science and Technology, Vols 126, 2018, pp 59-62 3) Luu Thi Lan Anh, Nguyen Thi Tuyet Mai, Mateus Manuel Neto, Ngoc Trung Nguyen, Ta Ngoc Dung, Trinh Xuan Anh, Phan Trung Nghia, Huynh Dang Chinh, and Vo Thach Son Effect of WO3 Doped TiO2 Nanoparticles for Solar Photocatalytic Degradation of Methyl Blue Asia worshop on polymer processing, 16-19/2017 Hanoi, Vietnam 4) Luu Thi Lan Anh, Nguyen Thi Tuyet Mai, Trinh Xuan Anh, Nguyen Kim Nga, Phan Trung Nghia, Ta Ngoc Dung, Huynh Dang Chinh, Mateus Manuel Neto and Vo Thach Son, Optimization of synthesized conditions of TiO2 photocatalysic nano particles using response surface methodology, Vietnam journal of Chemistry, Vol 53, issue 6e4 - 2015; pp 343-347 5) Lan Anh Luu Thi, Duc Hieu Nguyen, Mateus Manuel Neto, Ngoc Trung Nguyen and Thach Son Vo, Characterization of Nanocrystalline Titania Thin Film Deposited by Spray Pyrolysis Technique, Advanced Materials Research, Vols 875-877, 2014, pp 49-53 6) Mateus Manuel Neto, Luu Thi Lan Anh, Nguyen Duc Hieu, Pham Phi Hung, Nguyen Ngoc Trung, and Vo Thach Son The influence of tropical climate on the operation of a grid connected photovoltaic thin-film amorphous silicon system Kỷ yếu Hội nghị Những Tiến Vật lý Kỹ Thuật Ứng dụng, Tp Huế, 08-12 tháng 10 năm 2013 Tr.375381 ISBN: 978-604-913-232-2 121 REFERENCES [1] sdg.iisd.org/news/november-2015-sustainable-energy-finance-update [2] Belward A, Bisselink B, Bódis K, Brink A, Dallemand J, De Roo A, Huld T, Kayitakire F, Mayaux P, Ossenbrink H, Pinedo I, Sint H, Thielen J, Szabó S, Tromboni U, Willemen L, Monforti F., (2011), ‘Renewable energies in Africa’, JRC scientific technical reports, 1- 62 [3] www.meeco.net/blog/angola-homeowner-chooses-solar-and-energy-storage-over-diesel’ [4] E Martinot et all, (2012), ‘Renewable Energy Sources and Climate Change Mitigation Special Report of the Intergovernmental Panel on Climate Change’, Cambridge University Press, 1-1088 [5] www.realclearscience.com/blog/Energy%20Cost%20 Chart %20Two.png [6] B Tsai et al., (2012), ‘Performance of an INER HCPV Module in NPUST’, Energy Procedia, vol 14, 893 - 898 [7] L A Turner et al (2011), ‘The Renewable Energy Review’, Renew Energy Rev Committee Clim Chang.’, 1-166 [8] N M Komerath, P P Komerath, (2011), ‘Terrestrial Micro Renewable Energy Applications of Space Technology’ , Phys Procedia, 1-5 [9] M Martin-Gonzalez, O Caballero-Calero, P Diaz-Chao, (2013), ‘Nanoengineering thermoelectrics for 21st century: Energy harvesting and other trends in the field’, Renew Sustain Energy Rev, vol 24, 288-305 [10] C Grasso, K Ernst, R Könenkamp, (2001), ‘Photoelectrical characterization and modeling of the eta-solar cell’, Proc 17th Eur Photovolt Sol Energy Conf., vol I, 211-214 [11] N Hultman, D Rebois, M Scholten, C Ramig, (2011), ‘The greenhouse impact of unconventional gas for electricity generation’, Environ Res Lett., 6, 0044008, 1- [12] H Gujba, Y Mulugetta, A Azapagic, (2011), ‘Power generation scenarios for Nigeria: an environmental and cost assessment’, Energy Policy; 39(2), 968-80 [13] A Jäger-Waldau, (2017), ‘PV Status report’, SBN 978-92-79-74071-8, -83 [14] https://www.google.co.uk/search? [15] www.angolaenergia2025.com/en/conteudo/grid-expansion [16] D Neamen,(2012), ‘Semiconductor Device Physics: Basic Principles’, in 4th ed McGraw-Hill, New York, NY, USA [17] P Würfel, (2005), ‘Physics of Solar Cells’, WILEY-VCH, ISBN-13: 978-1860943492 [18] A Luque, S Hegedus, (2003), ‘Handbook of Photovoltaic Science and Engineering’, John Wiley Sons Ltd, ISBN: 978-0-470-72169-8, 1-1164 [19] S J Fonash, (2010), ‘Solar cell device physics’, Boulevard, Langford Lane,Kidlington, Oxford, ISBN 978-0-12-374774-7, 1-354 [20] A Einstein, (1905), ‘On the electrodynamics of moving bodies’, Ann Phys 322, 891 [21] A Goodrich et al., (2013) ‘A wafer-based monocrystalline silicon photovoltaics road map: utilizing known technology improvement opportunities for further reductions in manufacturing costs’, Sol Energy Mater Sol Cells, 114, 110 - 350 [22] T Soga, (2006), ‘Nanostructured Materials for Solar Energy Conversion’, ISBN-13: 122 978-0-444-52844-5, 1-615 [23] T Soga, (2006), ‘Nanostructured Materials for Solar Energy Conversion’, SBN-13: 978-0-444-52844-5, 1-615 [24] NREL, (2014), ‘Solar Photovoltaic Technology Basics’, U.S Department of Energy (www.nrel.gov/learning/re_photovoltaics.html) [25] A Sangster,(2014), ‘Solar photovoltaics’, Green Energy Technol, vol 194, no 4,145-72 [26] O O Osarumen, H A Emeka, N N Ekere, P O Olagbegi, (2017), ‘A review of photovoltaic module technologies for increased performance in tropical climate’, Renew Sustain Energy Rev., vol 75, 1225-1238 [27] D M Chapin, C S Fuller, G L Pearson, (1954), ‘A New Silicon p-n Junction Photocell for Converting Solar Radiation into Electrical Power’, J Appl Phys 25, 676-677 [28] W Shockley, H J Queisser, (1961), ‘Detailed Balance Limit of Efficiency of p-n Junction solar cells’, J Appl Phys 32, 510-519 [29] M A Green, K Emery, Y Hishikawa, W Warta, E D Dunlop, (2012), ‘Solar cell efficiency tables (version 40)’, Prog Photovolt Res Appl 20, 606-614 [30] B Hoex, (2008), ‘Functional thin films for high-efficiency solar cells’, Technische Universiteit Eindhoven [31] A Luque, S Hegedus, (2008), ‘Handbook of photovoltaic science and engineering’, Wiley [32] D Staebler, C Wronski, (1977), ‘Reversible conductivity changes in dischargeproduced amorphous Si’, Appl Phys Lett 31, 292-294 [33] G Dingemans, W M M Kessels, (2012), ‘Status and prospects of Al2O3-based surface passivation schemes for silicon solar cells’, J Vac Sci Technol A 30(4); 040802, 1-9 [34] R Dubeyl et al., (2014), ‘Performance degradation infield aged crystalline silicon PV modules in different Indian climatic conditions’, Photovoltaic Specialist Conference (PVSC) IEEE 40th [35] C Ike, (2013), ‘The Effect of temperature on the performance of A photovoltaic solar System In eastern Nigeria’, Res Inven Int J Eng Sci, vol 3(12), 10 - [36] S Mekhilef, R Saidur, M Kamalisarvestani, (2012), ‘Effect of dust, humidity and air velocity on efficiency of photovoltaic cells’, Renew Sustain Energy Rev, vol 16, 2920-2925 [37] A Ndiaye, A Charki, V Sambou, P A Ndiaye, (2015), ‘Photovoltaic Platform for Investigating PV Module Degradation’, Energy Procedia, vol 74, 1370-80 [38] T M Walsh, Z Xiong, Y S Khoo, A O Tay, A G Aberle, (2012), ‘Singapore Modules -optimised PV Modules for the tropics’, Energy Procedia, vol 15, 388 - 95 [39] IEC60904-3, (2008), ‘Photovoltaic devices - Part 3: Measurement principles for terrestrial photovoltaic (PV) solar devices with reference spectral irradiance data’, International Electrotechnical Commission, Geneva, Switzerland [40] T Danowicz, T Rodziewicz, Z.-W M, (2004), ‘Effect of air mass factor on the performance of different PV modules’, Opto-Electron Rev., vol 12, 69-73 [41] A Nakajima et al., (2004), ‘Spectral Effects of a Single-Junction Amorphous Silicon Solar Cell on Outdoor Performance’, Jpn J Appl Phys., vol 43, 2425-31 [42] D King, J Kratochvil, W Boyson, (1990), ‘Performance of Amorphous Silicon Photovoltaic Systems, 1985-1989: Sandia National Laboratories’, Photovolt Syst Res 123 [43] T R Betts, (2005), ‘Investigation of photovoltaic device operation under varying spectral conditions’, PhD, Electronic, Electrical and Systems Engineering, Loughborough University, UK [44] K Akhmad et al., (1997), ‘Outdoor performance of amorphous silicon and polycrystalline silicon PV modules’, Sol Energ Mat Sol Cells, vol 46, 209-218 [45] T Ishii, K Otani, T Takashima, Y Q Xue, (2013), ‘Solar spectral influence on the performance of photovoltaic (PV) modules under fine weather and cloudy weather conditions’, Prog Photovoltaics Res Appl, vol 21, 481- 489 [46] C Monokroussos et al., (2013) ‘Effects of spectrum on the power rating of amorphous silicon photovoltaic devices’, Prog Photovoltaics Res Appl., vol 19, 640-8 [47] C Cornaro, A Andreotti, (2013), ‘Influence of Average Photon Energy index on solar irradiance characteristics and outdoor performance of photovoltaic modules’, Prog Photovoltaics Res Appl., vol 21, 996 -1003 [48] T Minemoto, S Nagae, H Takakura, (2007), ‘Impact of spectral irradiance distribution and temperature on the outdoor performance of amorphous Si photovoltaic modules’, Sol Energ Mat Sol Cells, vol 91, 919 - 23 [49] C Sirisamphanwong, N Ketjoy, (2012), ‘Impact of spectral irradiance distribution on the outdoor performance of photovoltaic system under Thai climatic conditions’, Renew Energy, vol 38, 69 - 74 [50] T Ishii, K Otani, T Takashima, S Kawai, (2011), ‘Estimation of the maximum power temperature coefficients of PV modules at different time scales’, Sol Energ Mat Sol Cells, vol 95, 386 - [51] J Nelson (2003), ‘The Physics of Solar Cells’, Imp Coll Press [52] E Maruyama et al., ‘Sanyo’s challenges to the development of high-efficiency HIT solar cells and the expansion of HIT business’, in 4th World Conference on Photovoltaic Energy Conversion, Hawaii, 1-5 [53] J C C Fan (1986), ‘Theoretical temperature dependence of solar cell parameters’, Sol Cells, vol 17, 309 - 315 [54] E Skoplaki, J A Palyvos, (2009), ‘Operating temperature of photovoltaic modules: A survey of pertinent correlations’, Renew Energy, vol 34, 23 - 29 [55] M C A Garcıa, J L Balenzategui, (2004), ‘Estimation ofphotovoltaic module yearly temperature and performance based on Nominal Operation Cell Temperature calculations’, Renew Energy, vol 29, 1997 - 2010 [56] J Burdick, T Glatfelter, (1986), ‘Spectral response and I-V measurements of tandem amorphous-silicon alloy solar cells’, Sol Cells, vol 18, 301 - 14 [57] D L King, J A Kratochvil, W E Boyson, (1997), ‘Measuring solar spectral and angle-of-incidence effects on photovoltaic modules and solar irradiance sensors’, in 26th IEEE Photovoltaic Specialists Conference, 1113 - [58] G N Tiwari, S Dubey, (2010), ‘Fundamentals of Photovoltaic Modules and Their Applications’, R Soc Chem [59] Y S Khoo, J P Singh, T M Walsh, A G Aberle, (2014), ‘Comparison of angular reflectance losses between PV modules with planar and textured glass under Singapore outdoor conditions’, IEEE J Photovolt., vol 4, 362 - [60] T Swonke, R Auer, (2009), ‘Impact of moisture on PV module encapsulants’, Proc SPIE - Int Soc Opt Eng, vol 7412, 74120A 124 [61] B A L Gwandu, D J Creasey, (1995), ‘Humidity: a factor in the appropriate positioning of a photovoltaic power station’, Renew Energy, vol 6(3), 313 - 316 [62] H A A Kazem et al., (2012), ‘Effect of Humidity on the PV Performance in Oman’, Asian Trans Eng., vol 2(4), 29 - 32 [63] M K Panjwani, B NarejoG, (2014), ‘Effect of humidity on the efficiency of solar cell (photovoltaic)’, Int J Eng Res Gen Sci., vol 2(4) [64] V B Omubo-Pepple, C Israel-Cookey, G I Alamunokuma, (2009), ‘Effects of temperature, solar flux and relative humidity on the efficient conversion of solar energy to electricity’, Eur J Sci Res., vol 35, 173-180 [65] M T Cher, K E C Boon, P T Kok, (2010), ‘Humidity study of a-Si PV cell’, Microelectron Reliab., vol 50, 1871-1874 [66] H Jiang, L Lu, K Sun, (2011), ‘Experimental investigation of the impact of airborne dust deposition on the performance of solar photovoltaic (PV) modules’, Atmos Env 2011, vol 45, 4299 - 304 [67] B R Paudyal, S R Shakya, (2016), ‘Dust accumulation effects on efficiency of solar PV modules for off grid purpose: a case study of Kathmandu’, Sol Energy 2016, vol 135, 103-10 [68] M J Adinoyi, S S A M., (2013), ‘Effect of dust accumulation on the power outputs of solar photovoltaic modules’, Renew Energy, vol 60, 633-6 [69] S Kalogirou, R Agathokleous, G Panayiotou, (2013), ‘On-site PV characterization and the effect of soiling on their performance’, Energy 51, 439- 46 [70] L Micheli, M Muller, S Kurtz, (2016), ‘Determining the effects of environment and atmospheric parameters on PV field performance’, Proc IEEE 43r Photovolt Spec Conf (PVSC); 1724-9 [71] M C Hottel, B Woertz, (1942), ‘Performance of flat plate solar heat collectors’, ASME Trans., vol 64, 91-104 [72] Wakim, (1981), ‘Introduction of PV power generation to Kuwait’, Kuwait Inst Sci Res Kuwait City [73] A A M Sayigh, S Al-Jandal, H Ahmed, (1985), ‘Dust effect on solar flat surfaces devices in Kuwait’, Proc Work Phys Non-Conventional Energy Sources Mater Sci Energy, Triest, Italy, 353-367 [74] D Goossens, E V Kerschaever, (1999), ‘Aeolian dust deposition on photovoltaic solar cells: the effects of wind velocity and airborne dust concentration on cell performance’, Sol Energy, vol 66, 277-289 [75] G E Bunea, K E Wilson, Y Meydbray, M P Campbell, D M De Ceuster, (2006), ‘Low Light Performance of Mono-Crystalline Silicon Solar Cells’, 4th World Conf Photovolt Energy Conversion, 1312-4 [76] E Cuce, P Cuce, T Bali, (2013), ‘An experimental analysis of light intensity and temperature dependency of photovoltaic module parameters’, Appl Energy, 111, 374-382 [77] S Sze, (2002), ‘Physics of Semiconductor Devices’, Wiley (2nd Ed.) [78] J Merten, C Voz, A Munoz, M Asensi, J Andreu, (1999), ‘The role of the buffer layer in the light of a new equivalent circuit for amorphous silicon solar cells’, Sol Energy Mater Sol Cells, vol 57, 153-165 [79] Ayodeji Abiola-Ogedengbe, (2013), ‘Experimental investigation of wind effect on 125 solar panels’, Master thesis in Engineering Science The University of Western Ontario [80] Eurocode-1, (2006), ‘Actions on Structures General Actions.Part 1-4: Wind Actions SR EN 1991-1-4/2006.’ [81] A Radu, E Axinte, (1989), ‘Wind Forces on Structures Supporting Solar Collectors’, J Wind Engng A Ind Aerodyn 32, 89, 93-100 [82] G T Bitsuamlak, A K Dagnew, J Erwin, (2010), ‘Evaluation of Wind Loads on Solar Panel Modules Using CFD’, Fifth Internat Symp.on Comput Wind Engng.(CWE2010), Chapel Hill, North California, USA, May 23-27 [83] R Appels et al., (2013),‘Effect of soiling on photovoltaic modules’, Sol.Energy 96, 283-291 [84] H K Elminir et al., (2006), ‘Effect of dust on the transparent cover of solar collectors’, Energy Convers Manag 47, 3192-3203 [85] M Abderrezek, M Fathi, (2017), ‘Experimental study of the dust effect on photovoltaic panels’ energy yield’, Sol Energy 142, 308-320 [86] Y Jiang, L Lu, H Lu, (2016), ‘A novel model to estimate the cleaning frequency for dirty solar photovoltaic (PV) modules in desert environment’, Sol Energy 140, 236-240 [87] A Gholami, A Saboonchi, A A Alemrajabi, (2017), ‘Experimental study of factors affecting dust accumulation and their effects on the transmission coefficient of glass for solar applications’, Renew Energy 112, 466-473 [88] H.Gaofa , Chuande Zhou, Zelun Li, (2011), ‘Review of self-cleaning method for solar cell array’ Proc Eng 16, 640–645 [89] R B Williams, R Tanimoto, A Simonyan, et al., (2007), ‘Vibration characterization of self-cleaning solar panels with piezoceramic actuation’, Collect Tech Pap - 48th AIAA/ASME/ASCE/AHS/ASC Struct Struct Dyn Mater Conf 512–520 [90] P E Clark, F A Minetto, J Keller, et al., (2007), ‘Finding a dust mitigation strategy that works on the lunar surface’, 38th Lunar Planet Sci Texas [91] P Ragesh, V Anand Ganesh, S V Nair, and A S Nair, (2014), ‘A review on selfcleaning and multifunctional materials’, J Mater Chem A, vol 2, no 36, 14773-97 [92] A B D Cassie, (1948), ‘Contact Angles’, Disscus of the Faraday Soc., vol 3,11-16 [93] R N Wenzel, (1936), ‘Resistance of Solid Surfaces’, Ind Eng Chem., vol 28, 988-994 [94] B D Cassie, A B D Cassie, and S Baxter, (1944), ‘Of porous surfaces’, Trans Faraday Soc., vol 40, no 5, 546-551 [95] M G Salvaggio, R Passalacqua, S Abate, S Perathoner, and G Centi, (2015), ‘Transparent nanostructured titania coatings with selfcleaning and antireflective properties for photovoltaic glass surfaces’, Chem Eng Trans., vol 43, 745-750 [96] R J Isaifan et al., (2017), ‘Improved Self-cleaning Properties of an Efficient and Easy to Scale up TiO2 Thin Films Prepared by Adsorptive Self-Assembly’, Sci Rep., vol 7, no 1, 1-9 [97] C Liu, X Tang, C Mo, and Z Qiang, (2008), ‘Characterization and activity of visiblelight-driven TiO2 photocatalyst codoped with nitrogen and cerium’, J Solid State Chem., vol 181, no 4, 913-919 [98] A Fujishima, DAZX Tryk, (2008), ‘TiO2 photocatalysis and related surface phenomena’, Surf Sci Rep 63, 515-582 [99] M Piispanen, L Hupa, and (2011), ‘Comparison of self-cleaning properties of three 126 titania coatings on float glass’, Appl Surf Sci 258,1126-1131 [100] A Gholami, A A Alemrajabi, A Saboonchi, (2017), ‘Experimental study of selfcleaning property of titanium dioxide and nanospray coatings in solar applications’, Sol Energy 157; 559-565 [101] A Fujishima, Z Liu, X Zhang, T Murakami, (2008), ‘Sol-gel SiO2/TiO2 bi-layer films with self-cleaning and anti-reflection properties’, Sol Energy Mater Sol Cells 92, 1434-1438 [102] M A M L de Jesus et al., (2015), ‘Super hydrophilic self-cleaning surfaces based on TiO2 and TiO2/SiO2 composite films for photovoltaic module cover glass’, Jesuset al Appl Adhes Sci 35 [103] D Adak et al., (2017), ‘Self-cleaning V-TiO2:SiO2 thin-film coatings with enhanced transmission for solar glass cover and related applications’, Sol Energy 155;410-418 [104] V Štengl, S Bakardjieva, and N Murafa, (2009), ‘Preparation and photocatalytic activity of rare earth doped TiO2 nanoparticles’, Mater Chem Phys., vol 114, no 1, 217-226 [105] J Ben Naceur, R Mechiakh, F Bousbih, and R Chtourou, (2011), ‘Influences of the iron ion (Fe3+)-doping on structural and optical properties of nanocrystalline TiO2 thin films prepared by sol-gel spin coating’, Appl Surf Sci., vol 257, no 24, 10699-10703 [106] D V Wellia, Q C Xu, M A Sk, K H Lim, T M Lim, and T T Y Tan, (2011), ‘Experimental and theoretical studies of Fe-doped TiO2 films prepared by peroxo solgel method’, Appl Catal A Gen., vol 401, no 1-2, 98-105 [107] C Y W Lin, D Channei, P Koshy, A Nakaruk, and C C Sorrell, (2012), ‘Effect of Fe doping on TiO2 films prepared by spin coating’, Ceram Int., vol 38, no 5, 3943-3946 [108] Z Meng, L Zhu, J Choi, C Park, and W Oh, (2011), ‘Preparation , characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light’, Nanoscale Res Lett., vol 6, no 1, 459 [109] G F Cai et al.,(2013), ‘Solar Energy Materials & Solar Cells Ef fi cient electrochromic materials based on TiO2-WO3 core/shell nanorod arrays’, vol 117, 231238 [110] X Zhu et al., (2017), ‘Preparation , characterization and photocatalytic properties of La / WO3 composites’, J Mater Sci Mater Electron., [111] Z Da Meng, L Zhu, J G Choi, C Y Park, and W C Oh, (2011), ‘Preparation, characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light’, Nanoscale Res Lett., vol 6, no 1, 1-11 [112] O Access, (2015), ‘Structure and Photocatalytic Properties of TiO2-WO3 Composites Prepared by Electrophoretic Deposition’ IOP Conf Series: Materials Science and Engineering 77, 1-6 [113] Z Da Meng, L Zhu, J G Choi, C Y Park, and W C Oh, (2011), ‘Preparation, characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light’, Nanoscale Res Lett., vol 6, no 1, 1-11 [114] R A Carcel, L Andronic, and A Duta, (2012), ‘Photocatalytic activity and stability of TiO2 and WO3 thin films’, Mater Charact., vol 70, 68-73 [115] N.R Mathews, et al, (2009), ‘Solar Energy’, 83, 1499-1508 [116] N Mahdjoub, N Allen, P Kelly, V Vishnyakov, (2010), ‘Journal of Photochemistry and Photobiology A’, Chem 211, 59-64 127 [117] K.D Rogers, D W Lane, J D Painter, A Chapman, (2004), ‘Thin Solid Films’, 466, 97- 102 [118] J Ben Naceur, R Mechiakh, F Bousbih, R Chtourou, (2011), ‘Influences of the iron ion (Fe3+)-doping on structural and optical properties of nanocrystalline TiO2 thin films prepared by sol-gel spin coating’, Appl Surf Sci 257, 10699-10703 [119] Xiaona Lu, Yunfei Ma, Baozhu Tian, Jinlong Zhang, (2011), ‘Preparation and characterization of Fe-TiO2 films with high visible photoactivity by autoclaved-sol method at low temperature’, Solid State Sci 13, 625-629 [120] Y Lin, C Ferronato, N Deng, J M Chovelon, (2011), ‘Photocatalytic Water Treatment by Titanium Dioxide: Recent Updates’, Appl Catal B Environ 104, 353–360 [121] G A Armin, B B Matthew, H Bram, M Thomas, (2012), ‘Industrial Silicon Wafer Solar Cells - Status and Trends’, GREEN, 135 [122] A G Aberle, (2000), ‘Surface passivation of crystalline silicon solar cells: a review’, Prog Photovoltaics Res Appl (5), 473-487 [123] A G Aberle, (1999), ‘Crystalline Silion Solar Cells - Advanced Surface Passivation and Analysis - University of New South Wales, Sydney, Australia.’ [124] J Schmidt et al., ‘Surface Passivation of High-efficiency Silicon Solar Cells By Atomic-layer-deposited Al2O3’, Prog.Photovolt Res Appl 16; 461- 466 [125] R W Johnson, A Hultqvist, S F Bent, (2014), ‘A brief review of atomic layer deposition: from fundamentals to applications’, Mater Today 17 ; 1-11 [126] R Bock, S Mau, J Schmidt, R Brendel, (2010), ‘Back junction back-contact n-type silicon solar cells with screen-printed aluminum-alloyed emitter’, Appl Phys Lett 96, 263507-4 [127] Hele Savin et al., (2015), ‘Black silicon solar cells with interdigitated back-contacts achieve 22.1% efficiency’, Nat Nanotechnol Adv., 1-12 [128] R Hacker, A Hangleiter, (1994), ‘Intrinsic upper limits of the carrier lifetime in silicon’, J Appl Physics, 75 (11), 7570-7572 [129] A.G Aberle, S Glunz, W Warta, (1992), ‘Impact of illumination level and oxide parameters on Shockley-Read-Hall recombination at the Si-SiO2 interface’, J Appl Physics, 71 (9), 4422-4431 [130] Y Xiang, C Zhou, E Jia, W Wang, (2015), ‘Oxidation precursor dependence of atomic layer deposited Al2O3 films in a-Si:H(i)/Al2O3 surface passivation stacks’, Nanoscale Res Lett 10; 137-8 [131] L Q Zhu, Y H Liu, H L Zhang, H Xiao, L Q Guo, (2014), ‘Atomic layer deposited Al2O3 films for anti-reflectance and surface passivation applications’, Appl Surf Sci 288; 430-334 [132] D K Simon et al., (2014), ‘Symmetrical Al2O3 based passivation layers for p- and ntype silicon’, Sol Energy Mater Sol Cells 131; 72-76 [133] E C Onyiriuka and (1993), ‘Aluminum,titaniumboride, and nitride films sputter-deposited from multi component alloy targets studied by XPS’, Appl Spectrosc 47(1) 35-37 [134] A B Khatibani, S Rozati, (2014), ‘Growth and molarity effects on properties of alumina thin films obtained by spray pyrolysis’, Mat Sci Semicon Proc 18; 80-87 [135] B Hoex, J H Gillis, M C van de Sanden, W M Kessels, (2008), ‘On the c-Si surface passivation mechanism by the negative-chargedielectric Al2O3’, J Appl Physics, vol 104, 113703-113707 [136] Malygin et al., (2015), ‘From V B Aleskovskii’s “Framework” Hypothesis to the Method 128 of Molecular Layering/Atomic Layer Deposition’, Chem Vap Depos 21, 216-40 [137] Puurunen, L Riikka, (2016), ‘Short History of Atomic Layer Deposition: Tuomo Suntola’s Atomic Layer Epitaxy’, Chem Vap Depos 20, 332-44 [138] H B Profijt, S E Potts, M C M van de Sanden, W M M Kessels, J Vac, and (2011), ‘Plasma-Assisted Atomic Layer Deposition: Basics, Opportunities, and Challenges’, Sci Technol A 29, 050801 [139] S M George, (2010), ‘ Atomic Layer Deposition: overview ’, Chem Rev 110, 111-131 [140] T Suntola, J Antson, (1977), ‘Method for producing compound thin films US Patent No 4,058,430’ [141] V Miikkulainen, et al, (2013), ‘Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trend’, J Appl Phys 113 (2), 301-101 [142] J Yum, et al, (2011), ‘Atomic layer deposited beryllium oxide: Effective passivation layer for III-V metal/oxide/semiconductor devices’, J Appl Phys 109 (6) , 1-4 [143] K Uusi-Esko, M Karppinen, (2011), ‘Extensive Series of Hexagonal and Orthorhombic RMnO3 (R = Y, La, Sm, Tb, Yb, Lu) Thin Films by Atomic Layer Deposition’, Chem Mater 23 (7), 1835- 1840 [144] I Povey, et al, (2006), ‘Photonic crystal thin films of GaAs prepared by atomic layer deposition, Appl Phys Lett 89 (10), 1-4 [145] Richard W.Johnson, et al, (2014), ‘A brief review of atomic layer deposition: from fundamentals to applications’ Material Today, Volume 17, Issue 5, , 236-246 [146] V Pore, et al, (2009), ‘Atomic Layer Deposition of Metal Tellurides and Selenides Using Alkylsilyl Compounds of Tellurium and Selenium’, J Am Chem Soc 131 (10) 3478-3480 [147] J Haeberle et al., (2013), ‘Ellipsometry and XPS comparative studies of thermal and plasma enhanced atomic layer deposited Al2O3-films’, Beilstein J Nanotechnol 4; 732-742 [148] M Wilson et al., (2011), ‘QSS-μPCD measurement of lifetime in silicon wafers: Advantages and new applications’, Energy Procedia, vol 8, 128-134 [149] B P Dhonge et al., (2011), ‘Spray pyrolytic deposition of transparent aluminum oxide (Al2O3) films’, Appl Surf Sci 258, 1091-1096 [150] G Gauglitz, D S Moore, (2014), ‘Handbook of Spectroscopy’, 1523-1556 129 ... junction [2] Angola is in the Western region of southern Africa, occupying an area of approximately 1.246.700 km2, which makes Angola be the sixth largest country of Africa The extent of Angolan coastline... that 13.7 million Angolans (26.2%) have no structural access to electricity, especially in the rural south of Angola Because of the high irradiation levels (6.3 kWh/m2day in Angola) , Solar PV... square kilometer Luanda is capital in Angola The population of Luanda is about 6.5 million people Luanda is also urbanizing at approximately 4% annually Although Angola is a member of the Power Pool