Abstract
This study analyzed the inter-annual variability in solar radiation at Port Harcourt and Calabar, aiming at improving knowledge of solar resources. For the investigation, monthly mean global solar radiation data for fifteen years (2000 – 2014) was collected from Nigerian Meteorological Agency (NIMET), and the monthly mean extraterrestrial solar radiation was determined using globally recognized standard relation. The clearness index parameter was employed for characterizing the spatial variability of solar radiation for Calabar and Port Harcourt. The statistics of the monthly mean solar radiation deviations of Port Harcourt and Calabar was tested using the Kolmogorov–Smirnov method. The test results showed that they are normally distributed random variables. Furthermore, the analysis of sequential properties showed that the coefficients of the auto-correlation with lag 1 are significant for both stations. The auto-correlation coefficients with lag 1, though usually not significant, are negative for both stations. The auto regression lag 1 (AR-1) is the recommended procedure (model equation) for generating monthly solar radiation synthetic time series, with auto-correlation coefficients varying from 0.30 to 0.47 for both stations in the South-South of Nigeria. Citation: Amadi, S. (2020). Global Solar Radiation Characteristics at Calabar and Port Harcourt Cities in Nigeria. Trends in Renewable Energy, 6, 101-120. DOI: 10.17737/tre.2020.6.2.00114
Highlights
A wide range of solar energy applications, including modeling, design of solar crop dryers, and photovoltaic system sizing, requires a huge amount of knowledge of global solar radiation
4.1 Results The descriptive statistics of measured global solar radiation, calculated extraterrestrial solar radiation, and evaluated clearness indices for Port Harcourt and Calabar are shown in Tables 3 – 5
The characteristics of inter-annual variability of solar radiation were analyzed for Port Harcourt and Calabar
Summary
A wide range of solar energy applications, including modeling, design of solar crop dryers, and photovoltaic system sizing, requires a huge amount of knowledge of global solar radiation. The important role played by knowledge sharing in the subject of solar radiation and its subsequent exploitation has necessitated the need to develop ways of predicting the incident solar radiation in the interest of the regions of the globe like tropical Africa, where routine measurements are lacking in spite of the huge availability of solar energy in the region [1]. For sub-Saharan African countries such as Nigeria, the economic and efficient utilization of solar energy has become inevitable because of the abundance and reliability of solar energy resource. Offiong [4] stated that the mean daily solar radiation received in Nigeria is up to 20MJ/m2/day.
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