Assessing the distribution of monthly mean hourly solar irradiation at an African Equatorial site (original) (raw)
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Journal of the Nigerian Society of Physical Sciences
The intensity of solar energy that is received by a particular location is affected by most meteorological conditions including, the solar irradiance received by the location, precipitation, extreme heat as a result of the surface or ambient temperature, etc. We obtain the monthly global solar irradiation and ambient temperature for the three (3) eco-climatic zones in the south of Nigeria (17 locations) for 12 years (2005 - 2016) from the Photovoltaic Geographical Information System (PVGIS) Satellite. The goal of this study is to understand how regional meteorological conditions affect radiation and temperature reception. Monthly and annual trends were plotted and compared for both variables in each region to show the similarity or dichotomy in their trends. The Mann-Kendall (M-K) trend test has been adopted to reveal that the changes in the variations on an annual basis, and results showed that the trend were not significant for both variables. Box plots have been used to give a be...
A comprehensive review of empirical models for estimating global solar radiation in Africa
A B S T R A C T The accurate knowledge of global solar radiation is of vital requirement for surveys in agronomy, hydrology, ecology, sizing of the photovoltaic or thermal solar systems, solar architecture, molten salt power plant and supplying energy to natural processes like photosynthesis and estimates of their performances. However, measurement of global solar radiation is not available in most locations across Africa. During the past 36 years in order to estimate global solar radiation on the horizontal surface on both daily and monthly mean daily basis, numerous empirical models have been developed for several locations in Africa. As a result various input parameters have been utilized and different functional forms used. In this study aim at classifying and reviewing the empirical models employed for estimating global solar radiation in Africa. The empirical models so far utilized were classified into six main categories and presented based on the input parameters employed. The models were further reclassified into several main sub-classes (groups) and finally represented according to their developing year. On the whole, 732 empirical models and 65 functional forms were recorded in literature for estimating global solar radiation in Africa in this review. Thus, this review would provide solar energy researchers in terms of identifying the input parameters and functional forms widely employed up till now as well as recognizing their importance for estimating global solar radiation in several locations in Africa.
Daily averages of solar radiation measured at Iju, Nigeria in 2008
International Journal of the Physical Sciences, 2012
This work presents one year data of global solar radiation flux measured at a humid tropical location in West Africa (Iju, Nigeria; 7.15°N, 5.12°E) for the period 1st January to 31st December, 2008. The collected raw data were analyzed using Origin software and Excel spreadsheet to determine the daily means, daily minima and maxima for the period under consideration. The daily mean for the year was 143.66 ± 11.79 Wm-2 day-1 while the mean of the daily maximum for the year was 653.42 ± 32.33 Wm-2 day-1. The daily mean maximum of hourly global solar radiation flux was about 620 Wm-2 for the dry season and 430 Wm-2 for the wet season. The fluctuations in the daily averages were prominent during the wet season (April to October). The data set showed a double-peak daily mean average of about 200 Wm-2 day-1 in March and November and a minimum of about 90 Wm-2 day-1 in July and August.
Solar radiation climate in Africa
Solar Energy, 2004
This work is a first attempt to propose a map of the solar radiation climate in Africa. Such a map is very useful for preliminary assessment and modeling of solar energy systems. Following the approach adopted for Europe, a data set of monthly means of the daily clearness index has been assembled for 62 sites. A cluster analysis was applied
Validation of the Accuracy of NASA Solar Irradiation Data for Four African Regions
International Journal of Sustainable Development and Planning, 2022
Unfortunately, most developing countries lack meteorological data from weather stations due to a lack of measurement instruments or the absence of these stations. Currently, a variety of spatial databases, such as NASA/Power, Meteonorm, Solargis, and others, provide solar irradiation data for various places and time intervals. The goal of this study is to verify the accuracy of solar irradiation data from the National Aeronautics and Space Administration (NASA) database (free estimated data) by comparing them with ground-based measurements taken at four distinct locations in Algeria and Mauritania. Using six statistical parameters, data downloaded from the NASA site for 34 years, from 1984 to 2017, were averaged and compared to ground-based data recorded at M'Sila, Saida, Tamanrasset, and Nouakchott for one year (365 days) on daily (n = 365), monthly (n = 30 or 31), and annual (n = 12) time scales. It has been found that in the absence of daily measured global horizontal irradiation data for one year, the estimated multi-year average NASA data can be used instead. The use of estimated data over a long period is recommended. In the absence of actual solar irradiation data, solar energy projects in Algeria and Mauritania can rely on NASA's estimates.
GLOBAL SOLAR RADIATION STUDIES DUE TO SUNSHINE HOURS AND OTHER METEOROLOGICAL PARAMETERS
American Journal of Engineering and Applied Sciences, 2013
Multiple linear regression models were developed to estimate the monthly daily Sunshine Hours using four parameters during a period of eleven years (1997-2007) for locations in South Eastern Nigeria. These locations include Uyo (Latitude 5°18’53.7’’N), Calabar (Latitude 5°16’07.6’’N), Port Harcourt (Latitude 4°56’26.2’’N), Warri (Latitude 5°34’21.0’’N), Enugu (Latitude 6°27’42.42’’N), Owerri (Latitude 5°38’05.1’’N). The parameters include Relative Humidity, Maximum and Minimum temperatures, Rainfall and Wind Speed. The result of the correlations show that four variable correlations with the highest value of R for each of the six locations give the best result when considering the error term (RMSE). The models are Uyo (S = -16.876-2.065RF+0.237W+1.278T+0.129RH), Calabar (S = -11.049-6.540RF- 0.534W+0.142RH+1.127T), Portharcourt (S = -27.306+0.270RH+1.806T-0.281RH-1.114W), erri (S = 0.677+9.776RF-0.689W-0.057RH+0.900T), Enugu (S = 10.279+5.519RF-0.586W-0.079RH+0.217T), Warri (S = -22.424+0.272RH+1.388T-9.791RF-0.623W). But when considering average values for the six locations, the correlation gives (S = 15.395+0.159RH-0.131T+0.714RF+0.187W). Where RH is Relative humidity, T is the Difference in maximum and minimum temperature, RF is RainFall and W is wind speed. The developed models can be used in estimating Global solar radiation for the six locations under study. It can also be used to estimate Global solar radiation for other places in South Eastern Nigeria where only sunshine records are available.
A model for determining the global solar radiation for Makurdi, Nigeria
Renewable Energy, 2011
An empirical model for determining the monthly average daily global solar radiation on a horizontal surface for Makurdi, Nigeria (Latitude 7 7 0 N and Longitude 8 6 0 E) was developed using the AngstromePage equation. The solar radiation (W/m 2), hours of bright sunshine and cloudiness were measured hourly from 0600 H to 1800 H daily for 18 months. The constants 'a' and 'b' of the Angstrom linear type equation were determined by plotting the clearness index (H/H o) against the possible sunshine hours (n s /N) to obtain the line of best fit. The constant 'a' was obtained from the intercept of the line on the y-axis while the constant 'b' was obtained from the slope of the line. The developed model for determining the global horizontal solar radiation at the location was H ¼ H o [0.17 þ 0.68(n/N)] with a coefficient of correlation of 0.78. The mean bias error and root mean square error that were used to test the performance of the constants were 0.17% and 1.22% respectively. The measured solar radiation was compared with the solar radiation predicted by the model and no significant difference was found between them using F-LSD at P 0.05.
Analysis of solar radiation data for Port Harcourt, Nigeria
Solar Energy, 1992
The data on global irradiation incident on a horizontal surface in Port Harcourt during the 13year period 1977-1989 are analyzed and shown to vary with the climatic changes of the year. The range of variation is found to be greatest in August. Based on the calculated average monthly clearness index values only five seasonal patterns are identified for Port Harcourt. The percentage of days with duration of sunshine less than 1.5 h is 28.3% while that greater than 9 h is 4.3%. The Angstrom type of regression model relating total global irradiation to sunshine duration has been found to be reasonably adequate only if long-term average monthly values are used.
Open Journal of Modelling and Simulation, 2021
The importance of accurate knowledge about available global solar radiation in the design and development of various solar energy systems cannot be overemphasized. Most of the available models for predicting global solar radiation involve a plethora of input factors, some of which require special skills and equipment to measure. Such multi-factor models are complex and computationally demanding. To remove some burdens associated with such models, the use of simplified prototypes with reduced input factors has been proposed. It has been shown that a model with fewer input factors, that can be determined in a definite manner or whose attributes are directly observable, is often a better alternative. Therefore, the main object of this paper is to have models with a few variables that can easily be measured, developed for predicting global solar radiation. Two input factors, geographical location and season of the year, were considered. Using a 22-year interannual average daily insolation data from the database of the National Aeronautics and Space Administration (NASA) blended with the art of interpolation, empirical models were fashioned with the data for the five subregions of Africa. The results of the models' analysis indicate that the latitude component is the dominant locational factor. Furthermore, the new models exhibit optimal performance in comparison with existing models and constitute reliable predictive tools that are suitable for estimating global solar radiation for any practical application.
Estimation of Diffuse Solar Radiation in the North and Far North of Cameroon
European Scientific Journal, 2013
The successful design and effective utilization of solar energy systems and devices for application in various facets of human endeavors, such as power and water supply for industrial, agricultural and domestic uses, largely depend on the availability of information on solar radiation characteristic of the location in which the system and devices should be situated. The diffuse radiation of four stations in North and Far North of Cameroon was estimated. A statistical analysis of monthly mean correlation was examined, using a 20 years recorded (1985-2005) of monthly mean diffuse solar radiation obtained at the four selected meteorological stations throughout the area of North and Far North of Cameroon. The accuracy of the candidate correlations were performed in terms of the three widely used statistical indicators, mean bias (MBE), root mean square errors (RMSE) and t-statistic (TS). The results indicated the correlations relating the diffuse fraction (k d) with the clearness index (k t) and the estimated diffuse monthly solar radiation.