Analysis of solar photovoltaic module performance under tropical savannah climatic conditions of Kenya (Uasin Gishu County)

Abstract

Solar Photovoltaic (PV) is essential for the transition to clean and renewable energy in Kenya. However, it remains underutilized accounting for only 2.2 % of the country’s electricity generation mix as of December 2020. The obstacle in harnessing solar PV in Kenya has been linked to a lack of site specific design parameters and limited data on solar PV performance under different climatic conditions. This has been exacerbated by the overdependence on imported solar PV modules that are tested under standard conditions by manufactures. Therefore, the main objective of this study was to analyse solar PV module performance under Uasin Gishu County climatic conditions. The specific objectives were: To measure the power output of the PV modules under combined effect of temperature and irradiance, measure the I-V, P-V characteristics of the PV modules and simulate the PV modules performance using MATLAB/Simulink. The methodology involved rooftop installation of two 100W solar PV modules, one of mono-crystalline and the other of poly- crystalline technology, at Moi University (0.2861° N, and 35.2943° E). Data was collected daily from 7.00am to 6.00pm for five months (November 2020 - March 2021). The data on solar irradiance and module temperature was captured using light intensity and temperature sensors respectively while the data on voltage and current from the solar PV modules was captured by the electric power sensors. Analysis of the data collected indicated that both mono-crystalline and poly-crystalline modules were affected by module temperature and solar irradiance variation. As the temperature increased beyond 25 °C the current increased slightly while the power output and voltage dropped. However, the increase in solar irradiance increased the power output, current and voltage. At irradiance of 1023 W/m 2 , the results revealed a higher current and power output by mono-crystalline module at 6.27% and 5.62% respectively above the poly-crystalline while at irradiance of 702 W/m 2 , the current was 3.6% and power at 2.86% above that of polycrystalline. In the case of module temperature the mono-crystalline module still performed better. The current and power output increased by 3.87% and 6.7% respectively above the polycrystalline performance at 13 °C while at 28.5 °C the current of 4.11% and power of 2.97% above the poly-crystalline performance was recorded. In conclusion, the cell temperature and solar irradiance have a strong influence on the performance of solar PV modules and this varies with the type of solar cells technology. Based on the findings of this study the mono-crystalline solar PV technology is recommended for the Kenyan tropical savannah climate of Uasin Gishu.