Renewable Energy Resources and Technologies
Stephen Ndubuisi Nnamchi; Onyinyechi Adanma Nnamchi; Kevin Nnanye Nwaigwe; Zaid Oluwadurotimi Jagun; Johnson Ugochukwu Ezenwankwo
Abstract
This study conducts a comparative evaluation of the performance of modules and the arrays under standard test conditions. An equivalent circuit model was developed alongside a computational scheme. The model input data were obtained from the manufacturer’s specification datasheets. They were used ...
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This study conducts a comparative evaluation of the performance of modules and the arrays under standard test conditions. An equivalent circuit model was developed alongside a computational scheme. The model input data were obtained from the manufacturer’s specification datasheets. They were used to analyse the maximum Fill Factor (FF) and Relative Power Losses (RPL) for Parallel (P), Series (S) and Series-Parallel (SP) configurations. For matching modules, the RPL was insignificant, but for mismatched modules, the parallel configuration (P) and series-parallel (SP) yielded RPL of 1.3 %, while the series configuration (S) produced RPL of 2.6 %. Thus, short circuit defects associated with the P and SP configuration were well below the open circuit defects associated with the series configuration (S). These results clearly show that the large photovoltaic plant needs to be configured with multiple blocks or strings of SP configuration in order to suppress RPL. In addition, the designer and installers of large solar power plants should adopt modules with uniform electrical and thermal properties in the construction of large solar power plants. The trivial RPL associated with the matched modules should be taken into consideration, as well.
Renewable Energy Resources and Technologies
Muhamad Mustafa Mundu; Stephen Ndubuisi Nnamchi; Onyinyechi Adanma Nnamchi
Abstract
The present study is concerned with the development, estimation and validation of sunshine hours models (SHM) in Uganda. The SHM is based on geographical (latitude) and climatological (clearness index) indices. The meteosat data (1984-2018) acquired from the National Aeronautics and Space Administration ...
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The present study is concerned with the development, estimation and validation of sunshine hours models (SHM) in Uganda. The SHM is based on geographical (latitude) and climatological (clearness index) indices. The meteosat data (1984-2018) acquired from the National Aeronautics and Space Administration were used to compute the coefficients of the models which, yielded a coefficient of determination close to unity, signifying a good association between the sunshine hours (SH) and the associated indices. The models become distributed by introducing a longitudinal function of clearness index into the primary SHM developed. Moreover, the models were subjected to statistical validation using; mean absolute relative error (MARE), root mean square error (RMSE) and mean absolute percentage difference (APD). Consequently, the primary SHM showed strong agreement with the measured SH data in the three regions with the exception of the northern region with flawed on-station data. Also, validation of the models by; {MARE, RMSE, APD} for Eastern, Central and Western regions, yielding the following results; {0.0788,0.5441,7.8778},{0.0390,0.1453,3.9013} and {0.0124,0.0528,1.2436}, respectively. The following maximum SH; 11.16, 7.87, 9.52, 8.86 and 6.06 h were recorded for Non-regional, Northern, Eastern, Central and Western regions, respectively. Further, comparative validation with redeveloped global SHM showed that the present model stands in all the regions, whereas the global models validated only in the Eastern region. This is attributed to the synergy of geographical and climatological indices against the global models only based on climatological index. The model results show the order of regional SH distribution; eastern>northern>central>western region. These results could be employed in solar power, exploitation and agrometeorology development. This study further recommends for adoption of the present model to non-equatorial regions upon redevelopment as a meaningful extension of this work.