Correlation Analysis between Meteorological Parameters and Solar Radiation for Utility-scale Photovoltaic Farm Development in Imo State, South-Eastern Nigeria

Abstract

Solar photovoltaic (PV) technology has become a technically feasible and economically viable option for addressing electricity supply deficits in Imo State and Nigeria. This research paper presents a correlation analysis between some major meteorological variables, including maximum temperature, minimum temperature, rainfall rate (the intensity of rainfall at a given time measured in mm/hr), relative humidity, rainfall amount, and sunshine duration in Imo State, South-Eastern Nigeria, over a period of six years (2015-2020). The study describes the solar energy potential and evaluates the technical potential to develop utility-scale photovoltaic (PV) solar farms. Data were sourced from the Nigerian Meteorological Agency (NiMet) and Tropospheric Data Acquisition Network (TRODAN). Statistical findings from one-way ANOVA, Tukey HSD pairwise comparisons, linear regression trend analysis, and Pearson correlation are employed in this analysis. Findings showed that the sunshine hours registered a mean of 8.9hours/day, and were strongly and positively correlated with maximum temperature (r = +0.6912), strongly negatively correlated with relative humidity (r = -0.9372) and rainfall amount (r = -0.6923).  A capacity factor of 17.58% during the dry season, 16.47% during the early period of the rainy season, 15.42% during the peak rainfall and 14.92% during the rainfall retreat resulted in an annual average capacity factor of 16.1%. This shows that Imo State has a very good economic potential to develop utility-scale solar Photovoltaic projects. The peak generation potential expected is about 68.02 MW during the dry season (November-March) with a capacity factor of 17.58%, and the lowest capacity factor of 14.92% is observed during the late rainfall/transition period, which indicates a manageable seasonal variability of about 7.92%. Although the results demonstrate strong solar potential in Imo State for utility-scale PV development, the study highlights the need for further investigation using long-term multi-decadal meteorological datasets to improve the reliability of solar resource estimation, reduce uncertainty in interannual climate variability and enhance the accuracy of long-term PV performance prediction. The study is significant as it provides a local empirical basis for assessing solar potential in Imo State, supports the planning and design of utility-scale PV systems, improves energy forecasting, and helps fill the gap in state-level solar resource studies in South-Eastern Nigeria.