Tag Archives: Solar Radiation

Global Solar Radiation Modeling on a Horizontal Surface Using Polynomial Fitting (Published)

An attempt has been made to use a polynomial fitting to model global solar radiation on a horizontal surface that was observed by using Pyranometer at University of Ghana Legon, (U.G), situated in Accra, Ghana. The observed solar radiation data was filtered by using fitting and smoothing methods. The polynomial data fitting method was tested by using different degrees of polynomial curve fittings. The root mean square error (RMSE) was used to calculate the error and the R2  (coefficient of determination) value was also determined. The polynomial fittings were carried out for various periods (pre- harmattan, early harmattan and late harmattan period) of the year. 

Keywords: Coefficient of Determination, Curve Fitting, Error, Polynomial, Pyranometer, RMSE, Smoothing, Solar Radiation

Global Solar Radiation Measurement in Abakaliki Ebonyi State Nigeria Using Locally Made Pyranometer (Published)

This research work focused on the variability of global solar radiation over the area of Abakaliki, Ebonyi State (6o20’N, 8o06’E) located in South Eastern part of Nigeria for the rainy and dry seasons. The Pyranometer used for this measurement was locally developed and calibrated against a standard pyranometer, it competed favorably with the standard Einstrain Lungs Sensor. The global solar radiation was measured every five minutes from 08:00hours to 18:00hours during the dry season 2011 and rainy season in 2012. The measurements were carried out near the New Physics Laboratory Complex Ebonyi State University Abakaliki, Nigeria. Maximum Irradiances of 1095.10Wm-2 and 689.48Wm-2 recorded in Abakaliki during dry and rainy seasons respectively occurred between 12:00 – 14:00hours local time, whereas the minimum values of 9.20Wm-2 and 9.86Wm-2 respectively are recorded during the sunrise and sunset. Partly cloudy conditions in Abakaliki cause conspicuous oscillations in global solar radiation. This can be attributed to multiple reflections by nearby cloudy layers. The seasonal difference in the observed global solar radiation was 405.62Wm-2. Therefore solar energy devices can operate continuously in Abakaliki for up to 10 hours in a solar day from 8:00hours to 18:00hours which was the period covered during this investigation.

Keywords: Irradiance, Measurement, Pyranometer, Solar Energy, Solar Radiation

SURVEY OF THE REFLECTIVITY OF THE EARTH’S ATMOSPHERE OVER SOME SELECTED CITIES IN NIGERIA (Published)

Solar radiation is rapidly gaining ground as a supplement to the non renewable sources of energy, which have a finite supply. But the amount of solar radiation reaching the Earth’s surface depends on the climatic and atmospheric conditions of the locations. This work evaluates the temporal and spatial variability of the reflectivity of the Earth’s atmosphere over Ibadan, Enugu, Sokoto and Kano, in order to access the effect of the atmospheric conditions on solar radiation in the areas. The data used for this study were obtained from the International Institute of Tropical Agriculture, Ibadan (1980-2010). The model for shortwave solar energy balance at the edge of the Earth’s atmosphere was adopted in this work. The results show that seasonally, the reflectivity obtained in this work ranged from 0.52 – 0.64, 0.46-0.55, 0.38-0.53, and 0.41-0.57 for Oyo, Enugu, Sokoto and Kano respectively. Annually, the reflectivity obtained ranged from 0.48-0.65, 0.36-0.64, 0.22-0.50 and 0.36-0.60 for Ibadan, Enugu, Sokoto and Kano respectively. This result may be due to the influence of the dry, dusty tropical-continental air mass and the warm, tropical-maritime air mass which control the atmospheric conditions of Nigeria. The atmospheric conditions of the selected cities for the period under review vary from being cloudy, heavily laden with harmattan dust, cloudless (clear) to dustless (clean), hence there is high prospect of solar technology in the areas. This information is useful to solar energy technology, environmental engineers and for climatic modeling. The results obtained were compared with the results of other places having almost latitudinal location and co-ordinates similar to the selected cities.

Keywords: : Reflectivity, Earth’s atmosphere, Nigeria, Renewable Energy, Solar Radiation

THE INFLUENCE OF VEGETATION ON MICROCLIMATE IN HOT HUMID TROPICAL ENVIRONMENT-A CASE OF ENUGU URBAN (Published)

Controlling direct solar radiation and increasing wind velocity to its Optimum capacity are part of planning strategies employed in the design of urban open spaces especially in hot humid tropical environment. Vegetation has the ability to reduce excessive air temperature through sunlight interception. Its geometric configuration influences the amount of solar radiation, air temperature, humidity and wind velocity on microclimate of a given area. Panning strategies aimed at reducing solar heat through application of vegetation were discussed. It also discussed the problem of thermal heat stress affecting the residents of Enugu Urban. The results were analyzed and solutions recommended

Keywords: Open Space, Planning Strategies, Solar Radiation, Tropical Environment, Urban Microclimate.