February 24, 10:01 am

Seminar room, Department of Physics


Seminar room, Department of Physics

SPEAKER 1: Samuel Munialo Wafula


TITLE:  Deposition and Characterization Of Titanium (Ii) Oxide/ Iron (Iii) Oxide /Niobium (V) Oxide Composites For Dye Sensitised Solar Cell Applications


SUPERVISORS: Dr. S. Waita & Dr. A. Ogacho



Titanium dioxide (TiO2) is one of the most commonly used semiconductor materials in a dye sensitized solar cells today. From literature, TiO2, is a material with wide band gap energy, low electrical conductivity and in its pure state, it has low light absorption. These properties limit it in the application as a solar material. Much effort has been done to narrow the band gap energy of TiO2 by doping it with other materials like ZnO, FeO, Al2O3, Nb2O5 etc., but still much has not been achieved. In this project, TiO2 materials will be doped with Fe+3 and Nb+5 ions in the optimized ratios, which will then be deposited on FTO glass substrates using electrophoretic method at a temperature of about 300C.The doping % will be varied from  5%, 10% and 15%. Four different categories of samples will be prepared i.e. TiO2, TiO2/Nb2O5, TiO2/Fe2O3 and TiO2/Nb2O5/Fe2O3.The ion concentrations, annealing temperatures, voltage quantity and deposition time will be optimized. The effect of the optimized parameters on the optical properties will be investigated using a double beam UV-VIS-NIR spectrophotometer. From the optical measurements, the optical properties like refractive index (n), extinction coefficient (K), absorption coefficient and band gap energy (Eg) will be estimated. The energy band gap will be approximated using Tauc plots. The structural properties of the films will be investigated using of Energy Dispersive X-ray fluorescence and X-ray diffraction. SCOUT software will be used to analyze the thickness of the film from the measured reflectance and transmittance. Electrical properties will be analyzed using a four-point probe.






SPEAKER 2: Rita Mwende


TITLE: Photovoltaic (PV) System Performance Forecasting And Modelling Using Real -Time Observation And Weather Data 


SUPERVISORS: Dr. S. Waita & Dr. G. O. Okeng'o



Photovoltaic (PV) systems have become an indispensable source of power for both commercial and domestic use in many developing countries including Kenya. However, it is difficult to fully integrate solar energy into the power grid and realize its full potential without proper modelling of the impact of selected environmental variables on PV system performance. This is because PV systems power output is intermittent and highly sensitive to weather conditions. Hence, proper evaluation, analysis and modelling of Photovoltaic (PV) systems performance is important for financing, design, installation, operation, budgeting and technical success. This research work aims at studying and modelling the effects of relative humidity, ambient temperature, wind speed, irradiance and PV module surface temperature on PV performance in order to come up with more accurate, flexible and customized models that can be used to predict solar power generation using weather forecasts data and real-time measurements. Machine learning techniques including several regression and Artificial Neural Networks will be implemented for PV systems performance forecasting. As an output, this work is expected to yield models for performing detailed analysis of PV systems performance with fewer errors. Such models harbor great economic benefits such as enabling reliable operational planning and proactive power trading within the private sector, municipalities, cities and regions in Kenya.


SPEAKER 3: Yoves Munala

TITLE: Underwater Solar Photovoltaic (PV) Systems Performance Analysis And Modelling

SUPERVISORS: Dr. S. Waita & Dr. G. O. Okeng'o


Photovoltaic (PV) systems are currently most favored as the longest-endurance solar energy sources for powering autonomous systems widely used in provision of situational analysis and environmental monitoring data. However, to date, use of PV systems power devices have only been limited to dry-land and space applications, with important underwater devices making use of shore-power and batteries that often lack long term endurance. Recently, research geared towards development of PV solar cells “tuned” to detect filtered penetrating underwater has been proposed as an alternative reliable source to provide power for underwater unmanned vehicles, sensors and cameras. Sunlight penetrating underwater experiences a decrease in its intensity due to a shift in the spectral energy towards blue light, making conventional solar cells to lose efficiency. High band-gap solar cells designed for space applications have been proposed as a viable alternative due to their possible high sensitivity to the bluer spectrum experienced underwater. However, a detailed and proper investigation of the performance of ordinary silicon PV solar cells is needed in order to generate reliable baseline data to steer ongoing research.  In this research work, we propose to carry out a performance analysis of PV solar cells placed at different depths under water in order to obtain a performance model for possible underwater power generation applications. Underwater photovoltaics have the potential of providing continuous power for long duration for unmanned remote sensor missions within depths up to several meters, and this will make recharging of the batteries easier, making them longer lived and finally reducing the overall cost of missions.

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Dr. G. Okengo