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Item Assessment of the thermal and energy performance of Photovoltaic modules in Agrivoltaics systems(University of Namibia, 2025) Mbalundu, Hertha Liina; Dobreva, PetjaThe study evaluates the thermal and energy performance of photovoltaic modules in an agrivoltaic system in Benin, west Africa. This was done by employing three sets of heat transfer coefficients: Faiman, Benin, and Büren into the Faiman module temperature prediction model. The dataset for this study extends from April to July 2023, marked by high ambient temperatures exceeding 30℃. According to the findings, the cooling effect was significant for the results of Büren coefficients, and the agrivoltaic system generated up to 3.0% more energy than the non-agrivoltaic, especially at higher module temperature ranges of 40 ℃ - 55 ℃. The Benin coefficients demonstrated a moderate cooling effect, evidenced by a positive energy yield difference of up to 1.0% in the month of May. However, the cooling effect reduced in the hotter month of July resulting in a -1.0% energy difference between the two systems. The Faiman coefficient, on the other hand, demonstrated no cooling effect, as shown by consistently yielding negative energy differences, especially in May (-1.0%). The statistical analysis indicates that the Faiman coefficients provided a closer fit to the actual Benin-derived temperatures (R2 : 0.99 and MAE: 0.54 ℃). Whereas the results from the Büren coefficients showed the strongest cooling effect, achieving a reduction in module temperatures of up to 4℃ relative to the non-agrivoltaic system. The findings highlight the need for site-specific coefficient tuning to enhance the accuracy and the reliability of the findingsItem Enhancing solar photovoltaic efficiency with porous silica coatings(University of Namibia, 2025) Namwiha, Leonard Etuna; Dobreva, PetjaSolar surface glass is known to exhibit reflectance loss of no less than 4%, depending on the angle of the incident light. Furthermore, the high operating temperature of the solar photovoltaic (PV) module also reduces the solar PV module efficiency by approximately 0.45 − 0.50 %/℃ depending on the temperature coefficient and the type of the solar modules[1]. The study investigated porous silica which is known to have high transmittance in the solar spectrum range (0.3-1.1μm) and high emissivity in the mid-infrared range (8-13μm) due to its bonding structure. The research employed the base/acid double catalysis technique of the sol-gel method, using Pluronic F127 as a surfactant, Tetraethylorthoxysilicate (TEOS), ethanol, hydrochloric acid, ammonium hydroxide, hexamethyldisilazane (HMDS) and distilled water to synthesise silicon dioxide sol. The sol was afterwards spin-coated on a glass substrate, resulting in a porous silica layer approximately 200 nm thick. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet-Visible-Near Infrared Spectroscopy (UV-Vis-NIR) spectrophotometer were employed to investigate the optical characteristics of the coatings. The study achieved an approximate 2% increase in transmittance within the solar spectrum (0.3- 1.1μm) with a single porous silica layer with 8% emissivity in the mid-infrared range (8-13μm). In addition, it observed a nearly 20% enhancement in emissivity with three layers in the mid-infrared range (8-13μm), while transmittance in the solar spectrum (0.3-1.1μm) decreased almost linearly by 8% from 0.3-0.55μm with three layersItem PV-powered membrane system control for continuous autonomous water solution in remote areas(University of Namibia, 2025) Kasheeta, Rauna Ndapandula; Dobreva, PetjaThis research addressed the challenge of Solar Irradiance (SI) fluctuations, which adversely affect the performance of photovoltaic-membrane (PV-membrane) systems used for water purification. These fluctuations lead to reduced permeate volume and quality, as well as increased specific energy consumption. The primary aim of this research is to incorporate mechanical energy storage and develop a hydraulic buffering control method to enhance system performance under varying SI conditions. To achieve this, a hydraulic energy storage system utilizing a bladder tank was implemented, designed to buffer periods of SI fluctuations. A control algorithm was developed that allows the hydraulic bladder accumulator to discharge during low solar irradiance periods for buffering and charge during high solar irradiance periods by monitoring power ramp down rates. Results indicate that, in the worst-case scenario of a very cloudy day, the system produced an additional 98.5 L of permeate while maintaining permeate quality within the WHO palatable limit of 1.13 mS/cm. Furthermore, the average specific energy consumption was reduced by 38%. The algorithm effectively prevented system pressure from dropping to zero, thereby maintaining system stability despite fluctuations caused by SI changes. Future investigations should focus on minimizing pump shutdowns during hydraulic buffering due to increased pressure resistance. This research contributes to sustainable water solutions in remote areas, offering a promising approach to enhance the reliability and efficiency of PV-powered membrane systemsItem Assessment of the performance of a Photovoltaic (pv) system for powering electrolysers in the green hydrogen project at Tsau//khaebs National Park using modelling and simulation approach(University of Namibia, 2025) Petrus, Jeremia Tangi; Dobreva, PetjaThe Namibian government, through the Southern Corridor Development Initiative (SCDI), aims to produce 300,000 tons of hydrogen annually at Tsau //Khaeb National Park using wind and solar energy. This thesis focuses on the PV system required to power the electrolyser, involving site analysis, component selection, and system optimisation using PVsyst and Fraunhofer Zenit. Economic evaluation was conducted via Levelized Cost of Energy (LCOE) calculations. A site investigation using QGIS, Google Earth, and SolarGIS determined the coordinates, area, topography, and solar resources. System sizing and optimisation indicated that 4,586,736 monofacial modules (610 W) are needed for the fixed-tilt system and 4,181,184 modules for the tracked system. The fixed system requires 803 inverters, while the tracked system needs 732. The land area required is 21.7 km² for the fixed system and 32.2 km² for the tracked system across both Springbok and Dolphin sites, respectively. Simulation results showed differences in performance ratio (PR). At Springbok, PVsyst reported 83.55% for the fixed system and 82.42% for the tracked system. At Dolphin, PR was 83.99% (fixed) and 82.75% (tracked). In Zenit, Springbok's PR was 76% (fixed) and 81.4% (tracked), while Dolphin's PR was 76.1% (fixed) and 81.6% (tracked). Zenit’s results were deemed more realistic due to its comprehensive modelling. The purpose of this study is to address the lack of independent research on the proposed SCDI Namibian Green Hydrogen project. The tracked system is recommended due to its superior performance, though further cost evaluations are necessary to address uncertaintiesItem Modelling and analysis of a photovoltaic system for a local business in Windhoek, Namibia(University of Namibia, 2025) Kauluma, Aina; Dobreva, PetjaPhotovoltaic (PV) technology generates electricity from light. There are two types of PV technologies in the market: traditional monofacial solar cells, which capture light on their front side, and emergent bifacial solar cells, which capture light on both their rear and front sides. Studies focusing on the performance of bifacial solar modules in Windhoek have not yet been conducted, so their potential advantages in this loca tion are unknown. The study aimed to model and evaluate the PV systems based on monofacial and bifacial silicon (Si) technologies. This feasability study was conducted for a business in Windhoek, Namibia. The evaluation was conducted by assessing the specific yield, performance ratio criteria, and the levelized cost of electricity (LCOE) for the systems modelled within the same specified location using the PVsyst soft ware. The systems are a bifacial single-axis tracking PV system, a bifacial fixed-tilt PV system, a monofacial single-axis tracking PV system, and a monofacial fixed-tilt PV system, all with similar technical parameters. The results showed that the en ergy production of the single-axis tracking bifacial system is higher than that of the monofacial system; however, there is no statistically significant difference between the two. On the other hand, the fixed-tilt bifacial PV system significantly outperforms the fixed-tilt monofacial PV system. Additionally, the single-axis tracking monofacial PV system has the shortest payback period of 3 years, 2 months with an ROI of 35.62%, while the fixed-tilt bifacial PV system has the longest payback period of 3 years, 8 months and an IRR of 31.50%. The system that performs the best financially is the single-axis tracking monofacial PV system with an LCOE of N$ 0.85/kWhItem Evaluation of titania-based thin films fabricated via the aqueous spray method for applications as anti-soiling coatings on solar cell cover glass(University of Namibia, 2025) Mwatile, Klaudia Ndawapeka; Hishimone, Philipus NThe growing demand for sustainable energy has made solar energy essential in the world energy transition. To maximize power output, solar PV systems must operate effectively. However, factors like soiling on the solar cell cover can reduce efficiency and overall power output. Traditional cleaning methods are typically expensive and labor-intensive, therefore emphasizing the need for simpler, cost-effective solutions like anti-soiling coatings. This study investigates the structural, optical, and photocatalytic properties of aluminum (Al), zinc (Zn), and copper (Cu) doped titanium dioxide (TiO₂) thin films prepared via an aqueous spray method. Aqueous precursor solutions were formulated by mixing Ti⁴⁺ complexes with Al³⁺, Zn²⁺, or Cu²⁺ complexes, with molar percentages varying from 0% to 10%. The results from UV-vis spectroscopy indicated that doping significantly enhanced the optical properties of TiO₂ thin films, with Al, Zn, and Cu-doped films showing higher transmittance than undoped TiO₂. X-ray diffraction (XRD) confirmed that all samples retained the anatase phase of TiO₂ without secondary phases of the dopants. Photocatalytic degradation tests revealed that 6% Cu-doped TiO₂ exhibited the highest degradation rate of 28% for methyl orange (MO), while 8% Al-doped and 2% Zn-doped films showed optimal activity at their respective levels. These findings suggest that doping TiO₂ thin films at appropriate doping concentrations can enhance their optical properties and photocatalytic efficiency, making them promising candidates for anti-soiling applications on solar cell coversItem Assessment of fire and explosion hazards in large-scale battery energy storage systems intended for Namibian green hydrogen projects(University of Namibia, 2025) John, Laudika Lifoshiwana; Dobreva, PetjaThe integration of large-scale battery energy storage systems (BESS) is a pivotal component in advancing Namibian green hydrogen projects, aimed to promote sustainable energy solutions. But there are serious fire and explosion risks associated with the use of Battery Energy Storage Systems, particularly those that use lithium-ion technology. These risks are intensified by the chemical instability of lithium-ion cells and operational challenges associated with large-scale systems. This research investigates the specific risks and failure modes associated with BESS, aiming to provide safety solutions and guidelines for their broader application in renewable energy projects. The study begins with a comprehensive literature review, identifying the primary causes of fires/explosions in lithium-ion batteries, leading to thermal runaway, like electrical faults, and mechanical damage. It also examines various battery chemistries and their respective safety profiles, alongside an analysis of global case studies to draw lessons for Namibia. Fault Tree Analysis (FTA) and statistical tests were employed to pinpoint critical failure mechanisms, with emphasis on factors such as system design, battery age, and operational states during failure events. The study creates a thorough risk assessment model that emphasizes the risks that come with large-scale battery energy storage (BESS). This model evaluates critical factors such as thermal runaway, mechanical stress, and system design. Additionally, study explores potential mitigation strategies, including advanced battery management systems, robust fire suppression mechanisms, and the use of alternative battery technologies to improve overall system safety. By addressing the inadequate safety guidelines, deficiencies in Battery Management Systems (BMS), and failure mode analysis in various operational states, this study provides critical insights and recommendations for enhancing the safety protocols and the regulatory framework for BESS in Namibia’s Green Hydrogen projects. The findings aim to contribute to the safe and efficient deployment of BESS, thereby supporting Namibia’s transition to a sustainable energy futureItem Data analysis of Markarian 421 observed by the high energy stereoscopic system (H.E.S.S.) in January 2017(University of Namibia, 2021) Nanghonga, Tauno Tuhafeni Kamudulunge; Backes, MThe investigation of Active Galactic Nuclei (AGN) is one of the most important areas of contemporary astrophysics. In general, the term AGN refers to the existence of energetic phenomena in the nucleus (central region) of a galaxy which cannot be attributed to the stars in that galaxy. Blazars are AGN that are viewed from Earth head on, and that exhibits extra-ordinary large variability on time scales sometimes less than hours, often displaying highly irregular and flare-like behavior. Among blazars detected at very-high energies, Markarian 421 is one of the brightest and best studied. It was detected by the High Energy Stereoscopic System (H.E.S.S.) in January 2017 during a flaring state. H.E.S.S. is a y-ray astronomy array of telescopes, located in Namibia, near the Gamsberg mountain, an area known for its excellent astronomical observational conditions. The observational data from the H.E.S.S. experiment was used in this case to obtain and explain the light curve and the energy spectrum for the seven data sets recorded in January 2017. With the Model++ (also called Paris Analysis) standard cuts analysis, an excess of 115.5 y rays, for Nan = 122 on-source and Naff = 108 off-source events are detected at the 19.9cr significance level. We have observed that the energy spectrum, can be well described by a power-law with spectral index 3.22± 0.27 decreasing in flux as the energy increases. Fitting the observed Spectral Energy Distribution (SED) with a power-law with exponential cut-off is observed to have the spectral index 0.80 ± 1.61 with the exponential cut at 2.53 ± 1.70 TeV photon energy. As for the light curves (the radiation flux as a function oftime), the scarcity ofthe data could not reveal any meaningful variability pattern to be deduced from these January 2017 observationsItem A geochemical baseline study of giant kelp (macrocystis pyrifera) at the kelp blue farm to assess carbon sequestration potential(University of Namibia, 2024) Mutjida, Protasius ShikushoThe raised levels of carbon dioxide (CO2) in the earth’s atmosphere have contributed to global climate change, which has adversely affected a wide range of individuals, communities, and organizations. One of the ways to mitigate climate change is to grow a huge amount of kelp forests that can absorb carbon dioxide from the atmosphere and sequester it in the deep ocean. To grow these forests, the right biogeochemical conditions (temperature, nutrients, oxygen, salinity, pH, trace metals and ions) within the ocean is vital to assess the sequestration potential and the impacts on the ocean health. This study aimed at monitoring the biogeochemical changes at the proposed Kelp Blue farm and surrounding areas further away from the farm. This study also aims to create a baseline of the chemical composition of the farm and Lüderitz areas, which has not been done before. Using the results obtained from the study, the potential of the cultivated giant kelp to sequester CO2 will be evaluated. This study measured the geochemical parameters using both in-situ probes and laboratory analyses at 10 different locations in Lüderitz (both offshore and coastal): offshore (within the Kelp Blue Pilot project farm, upstream of the farm in the Dumfudgeon rocks, downstream of the farm at Boot Bay and further south of Lüderitz at the Halifax island) and the coastal areas which are adjacent to the offshore study areas including at coastal site of Guano Bay which is about 17 km and the coastal area of Grossebucht which is about 20 km south the town of Lüderitz as another control site. This study also collected sediment samples at these offshore sites including further north of Walvis Bay at the different latitudinal transects. The sediments were analysed for trace metals by using a portable XRF and for carbon content by LOI (Loss on Ignition) method. Another geochemical analysis done was the titrimetric method to CO2 determination of seawater by using NaOH as a titrant the end points were determined. The concentrations of nutrients (phosphates and nitrites) in seawater samples were determined by adding them to a 10 mL cuvette, which had been zeroed first. A specific nutrient reagent was then introduced, and using ii prescribed sample preparation techniques, a spectrophotometer was employed to measure the concentrations of the nutrients in µg/L and mg/L. The geochemical parameters changed in relation to the seasonality and geographical positioning. In a season when the upwelling system was strong, the concentration of nutrients, acidity and the value of the pH, salinity, other geochemical parameters increased more, compared to other seasons and the further southern sampling sites resembled to that of the Southern Benguela Upwelling System (SBUS). Higher concentrations of phosphates (614 µg/L) were found in areas close to the islands. This is due to the presence of guanos. These remarkable long duration geochemical measuring results shows that the cultivated kelp can co-exist with other natural existing kelp beds in this ecosystem, and they can thrive more predominantly in season of great influx of nutrients during the season of strong winds. With a dynamic Benguela upwelling eastern boundary, these kelp forests have an enormous potential to grow more and will function as carbon absorber and eventually sequester more carbon when cultivated at larger scale. To quantify the carbon sequestration potential of these giant kelps, there are other areas to be investigated such as developing a sediment carbon baseline using isotopic analyses, lipid biomarkers, identifying sediment hotspots where the kelp will be deposited, developing a carbon dioxide removal model and geochemical dispersion models. All these other areas will be developed from the baseline being developed by this study. This study recommends that a continuous and rigorous monitoring of the water and sediment geochemical changes be done as the kelp forest grows and as the scale of operation expandsItem Investigation of the dependence of sheet resistance on the thickness of spin coated poly (3-Hexylthiophene) thin films(University of Namibia, 2024) Mutenda, Oliver SibengaSheet resistance (R□) and thickness of as-cast and post-treated poly(3- hexylthiophene) (P3HT) thin films fabricated on non-conductive glass substrates by the spin coating method, were determined under dark, and illuminated conditions. R□ of P3HT thin films of different thicknesses were compared, to examine the effect of illumination on the R□, and hence on the resistivity of the films. Commercially available P3HT was purchased and dissolved in chloroform (CHCl3). Glass slides were cleaned using detergent, acetone, and alcohol, in an ultrasonic bath, followed by cleaning in distilled water. P3HT thin films were fabricated by spin coating CHCl3 based solutions on cleaned, dry glass substrates, in ambient air. The films were annealed at a controlled temperature, and then the R□ of each thin film was measured, using the in-line four-point probe method. The thicknesses of the thin films were varied by varying the spin speed (ω) of the spin coater. The results showed a correlation between the R□ and the P3HT thin films’ thickness. The R□ reduces as the thicknesses of the P3HT thin films increase in the light, and in the dark, for as-cast, and annealed, P3HT thin films. Annealing also reduced the R□ of the P3HT thin films, and R□ showed some reductions when measured in the dark. The four-point probe method can be used to characterise materialsItem Radionuclide concentrations and radiation hazard assessment in the soil of Otjiwarongo, Namibia(University of Namibia, 2020) Kapofi, Naeman TuyoleniThe natural radioactivity and associated hazards in soil samples collected from the town of Otjiwarongo, Namibia, have been studied by gamma ray spectroscopy. The town was divided into ten geographical areas and five soil samples were collected across each area. The samples were dried, homogenized and 500 g of each sample was placed in a clearly-labelled 500 mL polythene bottle and sealed for four weeks. HPGe detector was subsequently used to obtain gamma ray spectra of the samples. The intensities of selected gamma lines were used to determine the activity concentrations of the primordial radionuclides 238U, 232Th, and 40K in the soil samples. The mean activity concentrations of the radionuclides in the ten geographical areas vary from 37.6 ± 7.4 to a high of 97.8 ± 46.2 Bq/kg for 238U, from 81.9 ± 16.7 to a very high of 852.8 ± 533.0 Bq/kg for 232Th and from 498.7 ± 55.7 to 807.1 ± 94.5 Bq/kg for 40K. All these mean activity concentrations are higher than the corresponding world-wide average values of 33.0 Bq/kg, 45.0 Bq/ kg and 420.0 Bq/kg for 238U, 232Th and 40K respectively, according to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000 report. Furthermore, the mean activity concentrations of some of the radionuclides in some areas are more than double those of the other areas thus indicating that the distribution of radionuclides in the soil of the town is not uniform. In order to assess the hazards associated with the radionuclides, different radiation hazard parameters such as absorbed dose rate, effective dose rate, radium equivalent activity (Raeq), and external radiation hazard index (Hex), were calculated from the activity concentrations of the radionuclides. The mean absorbed dose rates in the ten areas vary from 90.0 ± 13.7 to 593.9 ± 347.2 nGy h-1 and are all higher than the world average value of 60.0 nGy h-1 . However, the ii corresponding mean effective dose rates vary from 0.11 ± 0.01 to 0.73 ± 0.43 mSv/y which are all below the maximum permissible limit of 1 mSv/y, according to the International Commission on Radiological Protection (ICRP) reference level for public exposure control. Furthermore, the mean effective dose rates in seven of the areas are relatively low and below 0.2 mSv/y while those in the other three areas are relatively high and above 0.2 mSv/y. These results indicate that the level of radiation varies across the town and it is low in seven geographical areas but higher in three areas. The mean values of the radium equivalent activity in the ten areas vary from 197.9 ± 31.5 to a very high value of 1379.5 ± 815.7 Bq/kg. Again, the mean Raeq in the seven geographical areas are low and below the maximum permissible limit of 370 Bq/kg while they are high and above the permissible limit in the other three areas. Similarly, the mean values of Hex in the seven geographical areas are below the maximum permissible limit of unity but they are above the permissible limit in the other three areas. These results confirm that the level of ionizing radiation in most areas of Otjiwarongo is well-below the maximum permissible limit while the level in three other areas of the town is high and the hazard indices are above the maximum permissible limitItem The synthesis and characterization of chemical sensors and their application to anions and heavy metal ions sensing(University of Namibia, 2022) Amputu, Martha NiishiyeCations and anions play a major role in the biological and physiological processes in living organisms attracting more research interest in the area of chemical sensing. However, the excessive accumulation of ions in living organisms, particularly in humans, is toxic and can lead to health problems. Chemosensing is a powerful tool that can be employed to detect these ions in an environment. This is due to their high selectivity and sensitivity for the target analytes. Therefore, this research worked on designing two dual receptors namely A and C. These chemosensors were designed based on the fluorophore-spacer receptor principle and they have been synthesized based on the environmentally friendly and cost-effective Schiff base method. The synthesized chemosensors were characterized using a Proton Nuclear Magnetic Resonance (1H NMR), Fluorescence and Ultraviolet-visible (UV-Vis) spectrophotometer. The research findings have indicated that both receptor A and receptor C are colorimetrically and spectroscopically selective and sensitive to multiple cations and anions. Receptor A displayed a naked eye colorimetric sensitivity and spectrally towards; Co2+, Cu2+, Fe2+ while with the anions only spectral sensitivity was displayed. For both cations and anions a red shift in absorption with isosbestic points at 286 nm and 284 nm respectively, and fluorescence enhancement were observed, except for Fe2+, were no isosbestic point was observed and fluorescence quenching was noted. Similarly, receptor C presented both naked eye colorimetric sensitivity and spectrally towards these anions: CN- , F- , AcO- , OCN- , OH- and these cations: Cu2+, Fe2+ Zn2+, Ni2+, Hg2+. A bathochromic shift and fluorescence enhancement were observed with the anions, while for the cations absorption varies depending on the cations’ identity. Moreover, fluorescence quenching ii was observed with most cations, with an exemption for Hg2+ and Al3+ with fluorescence enhancement.Item Determination of endogenous and dietary-derived nitric oxide production in exhaled air of adult humans(University of Namibia, 2022) Keendjele, Tuwilika P.T.The production of nitric oxide (NO) has been demonstrated in the human body. Studies have elucidated that NO can either be produced endogenously via enzymatic action or through exogenous factors from dietary nitrate reduction. Exhaled nitric oxide (eNO) levels were also observed to be increased in inflammatory conditions, such as asthma and rhinitis, compared to normal physiological conditions. The aim of this study was to observe the production of NO in the body, the influence of dietary nitrate on eNO and factors affecting NO production. In this cross-sectional study, eNO in healthy, control participants (n=25) and compared to exhaled NO in participants with asthma (n=6) and participants with seasonal rhinitis (n=7). Exhaled NO in 20 healthy controls was also after supplementation with dietary nitrate. Asthmatic participant’s eNO concentrations (41±25 ppb) were higher compared to eNO in the control participants (12±12 ppb; p=0.04). There was no difference between eNO concentrations in participants with rhinitis (30±31 ppb) compared to control participants (12±12 ppb; p=0.21). There was also no dose-response relationship between the amount of dietary nitrate (nitrate-rich beetroot juice) and eNO concentration where eNO concentrations of 31±16 ppb, 34±31 ppb and 38±30 ppb; p=0.42 were measured for 35 mL, 70 mL and 140 mL of beetroot juice, respectively. A transient increase in eNO was observed after 30 minutes post-nitrate ingestion (20±8 ppb) compared to baseline eNO concentrations (6±5 ppb; p=0.03). The use of antibacterial mouthwash also reduced eNO concentrations post nitrate-ingestion (18±15 ppb) compared to beetroot ingestion without prior use of mouthwash (34±31 ppb; p=0.02). Exhaled NO levels were not reduced after antacid administration (p=0.791). The results of this study may indicate that the transient impact of dietary nitrate on eNO could account for the variations demonstrated in literature.Item Properties of front-end electronics of the compact high energy camera prototype for gamma-ray astronomy(University of Namibia, 2022) Nekwaya, Mwashana SusanaElectronics are a key component for all modern detector systems. The Compact High Energy Camera (CHEC) is a full-waveform camera designed for the dual-mirror Small Sized Telescopes (SST) of the Cherenkov Telescope Array (CTA). Some of the main components of the front-end electronics for CHEC are photo-sensors, preamplifiers and TARGET modules. CTA is planned to be a large observatory with up to 70 SSTs, with thousands of photosensor pixels per telescope (2048 camera channels per SST). The readout electronics for an array with such a high number of channels will cer tainly require a highly integrated and modular recording technology. In this study pulse waveforms generated by the camera channels and output by the preamplifier channels were analysed and parameterised in order to identify the different characteristics of the pulse waveforms. Characterising the pulse waveforms will help to better under stand the behaviour of different electronic channels during camera mass production and during observations as well. An automated analysis procedure that will be able to identify faulty camera channels has been established. A cubic spline has been fit to the data in order to get a good representation of the data and for better comparison of the behaviour of the different electronics channels. The interpolated pulse waveform has a gradually rounded peak, while the actual pulse waveform has a rather sharp peak. In addition, for comparing the behaviour of the different electronic channels, the fre quency distribution of the different characteristics are determined. In this study, it was found that the rise time of the pulse waveform is on average (7.0 ± 0.3) ns , with an average fall time of (15.0 ± 0.8) ns, while the interpolated fit has an average rise time of (6.0 ± 0.6) ns, thus showing consistency in the behaviour of the different channels.Item Determination of natural radioactivity in the soil of Omaruru, Namibia(University of Namibia, 2022) Mbuende, MerceyIn this study, the level of natural radioactivity and associated hazards has been evaluated for 50 soil samples from the town of Omaruru in western Namibia. Activity concentrations (Bqkg-1) of the primordial radionuclides 238U, 232Th and 40K in these soil samples were determined using a gamma-ray spectroscopy system with a High Purity Germanium detector (HPGe). These activity concentrations of the primordial radionuclides were calculated by using the intensities of selected gamma lines in the spectra as emitted by the radionuclides. The samples were collected from ten geographical areas which are inhabited localities in the town. The obtained results of activity concentrations for every soil sample was compared with the worldwide average values as recommended by UNSCEAR 2000. The values of activity concentration of 238U have been found to lie in the range of 39.4 - 111.1 Bq kg-1, with an average value of 63.9 ± 15.4 Bq kg-1, the values of activity concentration of 232Th ranged from 49.5 - 231.7 Bq kg-1 with an average value of 120.0 ± 42.9 Bq kg-1 and the values of activity concentration of 40K ranged from 692.4 - 1425.5 Bq kg-1, with an average value of 1136.7 ± 197.8 Bq kg-1 . The absorbed dose rates and annual effective dose as well as the radiation hazard indices in the soil samples, were calculated by employing the determined activity concentration values of 238U, 232Th and 40K. The total absorbed dose rate varied from 90.9 to 230.2 nGyh-1, with the average value of 149.4 ± 35.2 nGyh-1 and subsequently the annual effective dose ranged between 0.112 to 0.282 mSvy -1, with an average value of 0.183 ± 0.043 mSvy-1. This result of the annual effective dose is much lower than the recommended maximum permissible dose rate of 1.0 mSvy-1. The implication thereof is that the town of Omaruru has a normal background radiation. Additionally, the average value of the radium equivalent activity was 323.0 ± 80.2 Bq kg-1, and is lower than the recommended maximum value of 370 Bq kg-1. Furthermore, the average external hazard index, which was 0.87 ± 0.22, is also below the recommended safe level of 1. Based on these results, the radiological hazard is low in Omaruru. The results obtained in this study would be useful in establishing a baseline data to serve as a future reference in confirming possible changes in the environmental radioactivity as a result of any nuclear and related activities.Item Radionuclide analysis of soil samples taken from Outjo, Namibia(University of Namibia, 2019) Hanga, Lusina VenomufenuNaturally occurring radionuclides such as Uranium (238U), Thorium (232Th) and Potassium (40K), exist in the soil where they continuously disintegrate and emit ionising radiation which could pose health hazards to the inhabitants of a given location if the concentrations of the radionuclides are very high. In this work, the concentrations of the radionuclides 238U, 232Th and 40K in the soil samples taken from Outjo have been studied by gamma spectrometry. The town of Outjo was divided into ten geographical areas and five samples were collected across each area. These samples were dried under laboratory temperature, passed through a 2 mm mesh screen and sealed in 500 ml polythene bottles. The samples were analysed using a liquid nitrogen cooled High Purity Germanium (HPGe) detector (by Canberra). The Python Code was used to calculate the activity concentrations of- and Hazard indices due tothe radionuclides 238U, 232Th and 40K from the intensities of the gamma lines emitted. The results obtained show that the concentrations of radionuclides in the soils of the town of Outjo vary from 11. 7 ± 1.6 to 29. 8 ± 2.0 Bq kg-1 with an average of 20.5 ± 3.5 Bq kg-1 for 238U, 15.2 ± 1.8 to 58.3 ± 4.2 Bq kg-1 with an average of 31.4 ± 8.9 Bq kg-1 for 232Th and 206.2 ± 12.9 to 819.6 ± 31.9 Bq kg-1 with an average of 350.6 ± 124.6 Bq kg-1 for 40K. The average concentrations for 238U and 40K are lower than the worldwide averages of 35.0 Bq kg-1 and 400.0 Bq kg-1 respectively. In contrast, the average concentration for 232Th is slightly higher than the worldwide average of 30.0Bq kg-1. The average outdoor air absorbed dose rate due to terrestrial gamma rays at 1m abovethe ground was found to be 43.0 ± 10.6 nGyh-1 which is below the worldwide averagevalue of 58.0 nGyh-1. Also, the corresponding average effective dose was found to be0.05 ± 0.01 mSvy-1 which is below the maximum permissible limit of 1.0 mSvy-1. These results imply that the background radiation in the town is not high. The average values of Raeq and Hex are 92.4 ± 22.5 Bq kg-1 and 0.25 ± 0.06 which are below the recommended maximum limit of 370.0 Bq kg-1 and 1 respectively. Furthermore, the average values obtained for the other hazard parameters are all below the recommended maximum values, thus confirming that the town have normal background radiation so that radiation hazard is negligible in the town. All the results obtained in this study will contribute to the national baseline data of activity concentrations of radionuclides in the soils of Namibia.Item Techno-economic comparison and environmental impact assessment of a hybrid photovoltaic thermal solar system and a thermosiphon solar thermal hot water system with electric back up element, under Windhoek, Namibian conditions(University of Namibia, 2022) Shapingana, Laina TLack of accessible data on technical and economic evaluation of thermosiphon solar water heater (TS-SWH) and hybrid photovoltaic thermal (PVT) water heaters under Namibian conditions is limiting options available to decision makers on locally economic and opportune systems. This study compares the technical, economic aspects, and environmental impacts of TS-SWH and PVT water heaters. The TS-SWH installed in Otjomuise suburb, in Windhoek, were compared to PVT studied by others, in the UK and India. TS-SWH data was collected by Namibia Energy Institute using measuring instruments coupled to the systems. Both TS-SWH and PVT systems have the same technical make up, but the PVT system has solar PV cells on its collector. The findings of this study are that global radiation plays a major role in the operation of both solar water heaters and has influence on other parameters. TS-SWH of 1.2 m2 collector area results in about 6.3t of avoided CO2 as opposed to the PVT of the same aperture area that results in about 12.8t of avoided CO2 over their life span of 20 years, by interpolation of results by Herrando et al (1). PVT systems are cost effective, they cover domestic hot water demand completely and generate electricity simultaneously, in comparison to TS-SWH of same aperture area. TS-SWH has shown a solar fraction of 100%, specific solar energy yield of 470 kWh/m2 annually and return on investment of 7.7 years, in comparison, a PVT system has solar fraction is of about 68.6%, payback period of more than 20 years (2), a better energy yield of about 515 kWh/m2 annually and cogeneration efficiency of 66% (3). Installation of PVT systems for both domestic and commercial use country wide is recommended to reduce electricity demand and environmental impacts arising from generation of electricity from conventional methods. A study of PVT systems installed in Namibia and analysis of all year round data for TS-SWH is recommended for more reliable comparisons.Item A hybrid analysis approach to the high energy stereoscopic system phase II mono-analysis(University of Namibia, 2020) Shapopi, Jimmy NdawedapoThe High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes located in the Khomas highlands of Namibia. Their primary purpose is to detect Cherenkov light (CL) produced by particles in extensive air showers which are produced by incident high energy particles (gamma rays or cosmic rays) on the Earth's atmosphere. The array consists of four 107 m2 optical telescopes and a larger 614 m2 collective surface area telescope in the center of the array. The larger telescope has the ability of detecting showers induced by lower energy gamma rays therefore, it's addition to the array meant a lower threshold for the entire array. This can be accomplished by sophisticated analysis techniques, however, the analysis techniques that have thus far been used have not increased the integral sensitivity of the array as a whole as would be expected, but perform worse than the standard analysis technique at medium and high energies. Data taken by the H.E.S.S. telescopes is analyzed by fitting parameterized shower model images to actual images produced when observing a source, (Model++ Analysis) using a goodness of fit approach. This work explores the distribution of a shower parameter introduced in 2009, the depth of first interaction. Adjustments to the primary depth selection criteria to distinguish signal against noise are made and applied for a more sensitive result. Multi-wavelength lag studies from Cygnus X-3 are also presented. Light curve correlations between hard/soft X-rays versus radio emissions over long periods are studied. These studies are layed out as supporting suggestions that, lowering energy threshold while maintaining integral sensitivity to those energies would assist in the study of micro-quasars and possibly infer properties of quasars.Item Performance evaluation of Photovoltaic (PV) modules under different deployment conditions(University of Namibia, 2021) Michael, Poland AmutenyaThe purpose of this thesis is to evaluate the performance of solar modules, comprising various PV technologies, subject to different climatic conditions. The assessed PV technologies comprises of commercially available technologies and included Cadmium Telluride (CdTe), Copper Indium diSelenide (CIS), amorphous silicon (a-Si)and polycrystalline silicon (p-Si) modules. Commercially available photovoltaic (PV) modules currently are comprised of two main groups: crystalline silicon modules and thin film modules. The thin film modules are cheaper due to lower production cost. They also exhibit lower temperature coecients compared to crystalline silicon. There is a perception in the PV industry that thin film modules exhibit superior performance in hot climates and that they show better tolerance and performance in lower solar radiation locations. Our task was to determine if there is scientificc evidence for such perceptions. Measurements were done at two stations in South Africa with different climates: Port Elizabeth (PE), having a humid, relatively cool and with high cloud cover and Johannesburg (JB), having a warm, semi-arid and low cloud cover climate. In PE, one year of operation data for power output and module temperature measured at one minute time resolution were collected from the site while the GHI and ambient temperatures were measured from the site but downloaded from the SAURAN website. In JB, the power output and module temperature data measured at one minute time resolution were collected for a period of 6 months. The assessment was based on the following performance indicators: specific yield (SY), specific yield per unit land/roof area occupied by modules (SY/A) and the relative module efficiency ( rel:) for sunny (high irradiance) days and cloudy (low irradiance) days in each location. Statistical assessment of the performance indicators for each module type was performed with ANOVA test. The Tukey post-hoc test at 5% significance level was used for comparison of the daily SY, SY/A, rel: and average module temperatures between the different technologies at each location. A regression model was created to determine the extent of the impact of ambient conditions on the energy output of the modules. Our findings indicate that the solar radiation and ambient temperature have a strong impact on the module's SY, with the SY increasing linearly with the solar radiation while decreasing linearly with the ambient temperature during sunny days. Our findings further shows that the performance of all PV technology types are comparable in cloudy conditions at both locations. Under sunny conditions, CIS shows the highest SY in both locations, CdTe shows the highest SY/A in the warm and sunny JB climate while p-Si shows the highest SY/A under the cool and cloudy climate of PE, and a-Si shows the lowest SY, SY/A and rel: in PE. Furthermore, CIS remained the coolest and p-Si the hottest in the JB location. In PE, all modules were equally cool on average. In conclusion, significant difference in performance between different PV technologies is only observed during sunny conditions. In addition, the established differences during sunny conditions were not technology specific but rather dependent of the type of performance indicator assessed. Thin film technologies have shown vast differences in performance between technologies and between climatic conditions. The superior performance of thin film technologies in cloudy conditions could not be established. These results are based only on the first year of module deployment and can be expected to change with time due to module degradation.Item Analysis of tolerable capacity limits of intermittent photovoltaic power connected to the Namibian national electricity grid(University of Namibia, 2021) Katanga, Lusia NaamboGrid-connected photovoltaic (PV) systems are being utilized at an increasing level worldwide. Even though the increasing addition of intermittent PV power to the grid systems may lead to grid instability, PV systems feeding power into the Namibian electricity grid system are on the increase. The purpose of the study was to analyse the ability of the Namibian electricity grid system to accommodate intermittent solar PV power and to determine the capacity limit beyond which the Namibian electricity grid system will become unstable due to an increase in intermittent solar PV systems feeding power into the grid system. Data of interest was obtained from collected reports, journal articles, and other documents. This data was analyzed using quantitative methodological approaches and further classified, presented, and discussed. The Namibian grid system is considered strong when certain busbars achieve the SCR of 10 and the majority of the Namibian grid busbars can only connect less than 10MWof intermittent renewable electricity capacity without violating the short circuit ratio (SCR) limit. The capacity limits of intermittent solar PV power for the Namibian national grid system was calculated to be in the range of 38% to 53.4%. This study recommends that more research work and investigation from the perspective of engineering application and academic research are clearly required for more analysis regarding the strength and capacity limits of intermittent PV power of the Namibian grid system.