Photovoltaic Systems
Mustafa Arslan; Mehmet Cunkas
Abstract
Diffuse radiation is used in photovoltaic systems and other energy applications. Since global radiation is measured by local meteorological stations, it is possible to reach these radiation data. However, diffuse radiation is not usually measured, so it is not possible to obtain regular data on diffuse ...
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Diffuse radiation is used in photovoltaic systems and other energy applications. Since global radiation is measured by local meteorological stations, it is possible to reach these radiation data. However, diffuse radiation is not usually measured, so it is not possible to obtain regular data on diffuse radiation. For this reason, efforts are underway to develop various empirical models to estimate diffuse radiation. This paper aims to develop new empirical models to estimate the diffuse radiation values for Konya, Türkiye. The empirical models are used to determine the relationship between the diffuse fraction and the clearness index. Data from NASA-Surface meteorology and Solar Energy and the measured global solar were used. The three most suitable developed models were selected, and it was suggested to estimate the diffuse radiation. The developed models consist of 2nd, 3rd, and 4th-order polynomial regression models. The proposed models were tested to evaluate their performances by using eight statistical methods. These are Mean Bias Error (MBE), Mean Absolute Error (MAE), Mean Squared Error (MSE), Root Mean Squared Error (RMSE), Sum Squared Relative Error (SSRE), Relative Standard Error (RSE), Coefficient of determination (R2) and Correlation Coefficient (r). For the suggested models, the statistical parameters R2 value were calculated as 0.999705413, 1, and 1, and the RSE values were determined as 0.0084537, 0.000122, and 6.05E-06. The proposed models can contribute to researchers working on the applications of photovoltaic systems. The approaches could be used to estimate diffuse radiation elsewhere under similar climatic conditions.
Photovoltaic Systems
N.O. Adeniji; J.O. Adeniji; O. Ojeikere
Abstract
Global solar radiation is the sum total of all radiation reaching the earth surface i.e. it includes: the direct and the diffused solar radiation reaching the earth surface. The instrument used for measuring this very important component arriving from the whole hemisphere is the pyranometer. This is ...
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Global solar radiation is the sum total of all radiation reaching the earth surface i.e. it includes: the direct and the diffused solar radiation reaching the earth surface. The instrument used for measuring this very important component arriving from the whole hemisphere is the pyranometer. This is one of the most important parameter for applications, developments and researches related to alternative source of clean and renewable energy. In cases where these data are not available, it is very common to use computational models to estimate the missing data, which are based mainly on the search for relationships between weather variables, such as temperature, humidity, precipitation, cloud cover and sunshine hours, among others. In this research work, the baseline data for mean monthly global solar radiation and sunshine hours for three (3) geopolitical zones of Nigeria (sub-sahara regions of Nigeria) with Sokoto (North-western Nigeria) (12.910N, 5.200E), Maiduguri (North-eastern Nigeria) (11.850N, 13.080E) and Ilorin (North- Central Nigeria) (8.430N, 4.500E) were obtained from the Nigeria Metrological Agency (NIMET), Nigeria which spread from 1996 to 2010. A linear regression correlation model was developed and clearness index estimated for each station in this study. The result shows the Angstrom coefficients and for estimating global solar radiation for zone respectively, using the Angstrom-Prescott model. The average global solar radiation for these stations was estimated, results subjected to statistical tests proven to be good estimates. The study concluded that the Angstrom- Prescott model plays a significant role in predicting and estimating solar energy potentials in these regions