Technical Performance Assessment Of The Garissa Solar Power Plant in Kenya

Abstract

The Garissa Solar Power Plant is a significant contributor to Kenya's goal of achieving 100% clean energy by 2030. Despite its significance, the lack of publicly available analyzed technical performance data limits optimization of the plant’s efficiency and output. The main objective of this study was to assess the plant's technical performance based on key performance indicators. The study employed a structured approach to evaluate the plant's performance, adhering to the IEC61724-1 international standards. It focused on key indicators, namely; capacity utilization factor, specific yield, array yield, and performance ratio. The monthly and daily energy generation data were obtained from the Rural Electrification and Renewable Energy Corporation, while meteorological data were collected from the Photovoltaic Geographical Information System and the National Solar Radiation Database. Microsoft Excel software was utilized to apply theoretical formulas for computing and analyzing data. System Advisor Model software was used to conduct a performance analysis by integrating weather data, optimizing tilt and orientation, and simulating system design to determine the most efficient system. Lastly, the study compared the simulated and computed results based on the selected performance indicators. The power plant was analyzed over five years from 2019 to 2023. It exhibited an average annual performance ratio of 71.8%, capacity factor of 18.11%, system efficiency of 11.62% and specific yield of 1586.09 kWh/kWp. Analysis of irradiance data demonstrated a direct correlation with energy output: the highest recorded energy output was 7721 MWh at an irradiance of 204.34 kWh/m²/month, while the lowest was 6469 MWh at 169 kWh/m²/month. The wind speed and ambient temperature highlighted additional factors influencing solar power plant performance: variations in cell temperature from 37˚C to 41˚C and up to 49˚C correspond to energy outputs of 6469 MWh, 7812 MWh, and 7721 MWh, respectively. The tilt angle of 4˚, closely aligned with the latitude of 0.34˚S that was optimal and facilitated self-cleaning during rainy seasons. The study found the applied azimuth angle of 140˚ to be suboptimal for a location in the southern hemisphere, where the azimuth angle should face north to maximize exposure to sunlight throughout the day. The actual Ground Coverage Ratio (GCR) of 0.625 exceeded the recommended range of 0.3–0.5 and the optimal row spacing was calculated as 0.4 meters, less than the current 2 meters, indicating potential for increasing the number of arrays by reducing row spacing. Comparative analysis of actual versus simulated data revealed discrepancies, with simulated values indicating marginally higher performance metrics—specifically, a performance ratio of 80%, a capacity factor of 20.5%, system efficiency of 13.17%, and a specific energy yield of 1797 kWh/kWp. In conclusion, while the power plant's performance was average, significant opportunities for optimization existed to enhance efficiency and energy output. Recommendations included adjusting the azimuth angle to 0°, reducing inter-row spacing to 0.4 meters to accommodate more arrays, and implementing tailored maintenance strategies to mitigate soiling and vegetation growth, thereby improving the overall system efficiency of the solar power plant.