| dc.description.abstract | Abstract In Nigeria, the rapid population increase and the overreliance on fossil fuel have created significant environmental, health, political and economic consequences leading to severe socio-economic drawbacks. These factors have developed a wide gap between energy demand and supply due to insufficient local production, necessitating the need for a clean energy supply for all. The photovoltaic device's economic and environmental merits have made it the most suitable clean energy alternative to help developing countries such as Nigeria achieve the SDG-7. However, apart from the device's low efficiency, which is undergoing intensive study across the globe, another omnipresent factor is surface soiling, which is grossly underestimated and has a deleterious impact on a solar cell's performance. The accumulation of dust on photovoltaic (PV) devices adversely impacts their performance and is grossly underestimated. It is location-dependent and influenced by a number of factors, which raises concern for the potential investor, policymakers, engineers, and local populace in regions where the soiling rate and potential threats remain relatively unexplored. Energy losses from PV due to dust is an issue that cannot be ignored and can be an obstacle to achieving renewable energy targets in Nigeria. In this context, this thesis presents several mitigation techniques available to maintain a certain level of performance. This research begins with a systematic review of related literature on the country's energy crisis and renewable energy potential, leading to an overview of solar energy potential and penetration in the country, resulting in a comprehensive literature review on the effect of dust on PV performance. Several studies investigating factors influencing dust accumulation were conducted: First, indoor research investigated soiling on photovoltaic modules, focusing on dust properties and PV surface materials as influencing factors. Solar simulators, the spectrometer and SEM/EDX, were used to characterise the effect of accumulation of 13 different samples (ash, bird droppings, carpet dust, cement, charcoal, clay, coarse sand, laterite, loam soil, salt, sandy soil, stone dust and wood dust) on PV performance. Besides, the same experiment examines the performance of two leading PV covering materials (low iron glass and acrylic plastic). Outdoor studies investigated the influence of angular dependencies and optical losses in Abuja and across the country's six geopolitical zones by employing a low-cost coupon holder to expose low iron glass (50 mm x 50 mm) considering time stamp (annual, seasonal, and monthly variation). Soiled coupons were subjected to optical characterisation using a spectrometer and imaging analysis by employing SEM/EDX. Four PV modules (Monocrystalline Silicon, Polycrystalline Silicon, Cadmium Telluride and amorphous Silicon) were exposed in the Northern region to investigate PV yield reduction and correlate with yield measured under standard conditions. Low iron coupons were also exposed at the same period to determine the optical losses using a spectrometer and minerals morphology employing SEM/EDX. Finally, a correlation in-situ study to examine five cost-effective PV soiling mitigation techniques was conducted to determine the most effective and suitable approach by employing two types of PV surface covering materials (low iron glass and acrylic plastic) considering seasonal variation. The findings confirm that the country is blessed with enormous solar energy potential. However, its penetration is low, and the majority of the population is suffering from energy starvation. Findings from the review highlight dust accumulation on PV as one of the main obstacles preventing solar energy penetration. The indoor study findings reveal alarming losses showing that charcoal has the worst degradation effect on PV performance with approximately 98% reduction in short circuit current, while salt seems to have the most negligible impact with about 7%. It shows that acrylic plastic accumulates more dust than low iron glass and wet deposition promotes more adhesion on coupons than dry deposition. The outdoor studies' results revealed that the highest reduction in transmittance was recorded on a horizontally positioned coupon with a significant decrease of about 88% and lowest on a vertically positioned coupon with a reduction in the region of 1%. Similarly, the most significant mass of 12.56 g/m2 was recorded on a horizontally exposed coupon. It is observed that higher losses were recorded on a coupon positioned in the horizontal plane. Optical losses findings were used to develop soiling, which was correlated with another map revealing a significant variation. The PV performance experiment results reveal a significant decrease of ISC on all the modules with 73% on a-Si and the lowest of about 65% Si. It shows a yield loss of 78.3% for a-Si, 77% for CdTe, 70% for pc-Si, and 68.6% for the mc-Si module. Efficiencies decline of 78% for a-Si, 77% for CdTe, 71% for pc-Si and 71% for mc-Si. The optical loss results validated the output performance losses with a similar trend. The cleaning technique experimental findings show that the self-cleaning approach provides high preventive and restorative performance during the wet season, with about 99% on a low iron glass. Both manual cleanings with squeegee/water and self-cleaning demonstrated a 95% performance during the dry season on a low iron glass coupon. The least effective performance was recorded on the natural cleaning during the dry season with about 28% reduction in a month. The ramifications caused by soiling cannot be overlooked or overemphasised; thus, it is recommended to deploy PV modules in outdoor conditions and further examine each soiling mitigation technique's effectiveness and cost analysis over a longer duration in different regions. | en_GB |
