Solar Radiation Index Research Articles

Photovoltaic solar energy in Brazil: a review

Brazil has a high energy potential taking into account the region with the lowest solar radiation index in our territory, located in the state of Santa Catarina, it is observed that it is higher than several other regions in the world, especially in comparison with countries that stand out in implementation and investment of the sector. The present study aims to present a brief analysis of the concept of photovoltaic solar energy generation, providing a history of implementation in our country, also presenting a current panorama, government incentives through energy policy and future perspectives. It was not intended to carry out a case study for the implementation of a system, nor to present statistical comparisons with other nations.

Modeling the Impact of Climate Change on Sustainable Production of Two Legumes Important Economically and for Food Security: Mungbeans and Cowpeas in Ethiopia

Climate change is one of the most serious threats to global crops production at present and it will continue to be the largest threat in the future worldwide. Knowing how climate change affects crop productivity might help sustainability and crop improvement efforts. Under existing and projected climate change scenarios (2050s and 2070s in Ethiopia), the effect of global warming on the distribution of V. radiata and V. unguiculata was investigated. MaxEnt models were used to predict the current and future distribution pattern changes of these crops in Ethiopia using different climate change scenarios (i.e., lowest (RCP 2.6), moderate (RCP 4.5), and extreme (RCP 8.5)) for the years 2050s and 2070s. The study includes 81 and 68 occurrence points for V. radiata and V. unguiculata, respectively, along with 22 environmental variables. The suitability maps indicate that the Beneshangul Gumuz, Oromia, Amhara, SNNPR, and Tigray regions are the major Ethiopian regions with the potential to produce V. radiata, while Amhara, Gambella, Oromia, SNNPR, and Tigray are suitable for producing V. unguiculata. The model prediction for V. radiata habitat ranges distribution in Ethiopia indicated that 1.69%, 4.27%, 11.25% and 82.79% are estimated to be highly suitable, moderately suitable, less suitable, and unsuitable, respectively. On the other hand, the distribution of V. unguiculata is predicted to have 1.27%, 3.07%, 5.22%, and 90.44% habitat ranges that are highly suitable, moderately suitable, less suitable, and unsuitable, respectively, under the current climate change scenario by the year (2050s and 2070s) in Ethiopia. Among the environmental variables, precipitation of the wettest quarter (Bio16), solar radiation index (SRI), temperature seasonality (Bio4), and precipitation seasonality (Bio15) are discovered to be the most effective factors for defining habitat suitability for V. radiata, while precipitation of the wettest quarter (Bio16), temperature annual range (Bio7) and precipitation of the driest quarter (Bio17) found to be better habitat suitability indicator for V. unguiculata in Ethiopia. The result indicates that these variables were more relevant in predicting suitable habitat for these crops in Ethiopia. A future projection predicts that the suitable distribution region will become increasingly fragmented. In general, the study provides a scientific basis of suitable agro-ecological habitat for V. radiata and V. unguiculata for long-term crop management and production improvement in Ethiopia. Therefore, projections of current and future climate change impacts on such crops are vital to reduce the risk of crop failure and to identify the potential productive areas in the country.

1H HR-MAS NMR chemical profile and chemometric analysis as a tool for quality control of different cultivars of green tea (Camellia sinensis)

Green tea is a product obtained from the processing of fresh leaves of Camellia sinensis (L.) O. Kuntze species. In this study, the influence of climatic parameters on the chemical composition of green tea cultivars ('Yabukita' and 'Yutakamidori') over the harvest was evaluated using HR-MAS NMR. 'Yabukita' showed higher concentrations of epicatechin while higher amounts of theanine and caffeine were found in 'Yutakamidori'. The decline of theanine was associated with high average maximum temperature and solar radiation index, this latter also seemed to be responsible for relevant changes in epicatechin concentrations. It was not possible to associate any trend between climatic parameters and caffeine concentration. Fluctuations in linolenic acid concentration were monitored during the harvest period and were associated with the plant's defense mechanism. Monitoring of green tea over seasons and correlating the fluctuations of compounds to climatic parameters might become an efficient strategy for establishing quality standards for green teas.

Jute Fibers Synergy with nZVI/GO: Superficial Properties Enhancement for Arsenic Removal in Water with Possible Application in Dynamic Flow Filtration Systems.

Groundwater is one of the primary sources of water for both drinking and industrial use in northeastern Mexican territory, around 46% of the total, due to the lack of precipitation during the year and solar radiation index. The presence of arsenic in brackish soil and groundwater is a severe health issue, specifically in semi-arid and arid regions in the north of Mexico. Additionally, it represents the only source of drinking water in communities far from big cities, mainly due to the absence of hydric infrastructure. This work presents a new approach to treating polluted water with arsenic. The system based on activating jute fiber with nanoparticles of zero-valent iron immobilized over graphene oxide will allow nZVI particles to preserve their unique qualities for water sanitization. A dynamic flow test was designed to determine the effectivity of activated jute fibers as a water sanitation system. The results showed a reduction in the total arsenic content from 350 ppb to 34 ppb with a filtrate flow of 20 mL/min. The above represents 90% adsorption by the activated fiber. The analyzed sample corresponds to contaminated groundwater taken from Coahuila, Mexico. This sanitation system could be applied to low-income populations lacking robust infrastructure, such arsenic treatment plants.

Geospatial modeling for selection of optimum sites for hybrid solar-wind energy in Assiut Governorate, Egypt

Renewable energy resources are strategic solutions to develop remote urban areas, provide accessibility, meet the growing energy needs, prevent and mitigate adverse environmental impacts of anthropogenic activities. The purpose of the current research paper is to map and designate optimal sites for locating new hybrid solar and wind farms that fulfill suitability criteria for photovoltaic power plants and wind power in Assiut Governorate. SRTM digital elevation model was processed using the ESRI ArcGIS Area solar radiation tool to estimate and map insolation across the landscape on the topographic surface. Same data (SRTM DEM) was used together with the average wind speed map at elevation 50 m to calculate the wind power density. A geospatial model was designed based on three criteria sets covering three themes: first energy resource (climate and topography), second least cost (infrastructure and third, environmental constraints. The Analytic Hierarchy Process, Weighted Linear Combination and Binary overlay methods were applied, resulting in three sub-models. Such were further combined to produce the solar radiation and the wind power suitability indices separately. The solar radiation index values were reclassified; zones with a minimum threshold of 4 kw/m2/day were selected. From such zones, twenty optimum solar sites were selected based on a minimum area threshold. To identify potential wind zones, a minimum of wind power density equivalent to 220 W/m2 was considered. Results reveal that six potential solar sites exist within the potential wind energy zones; such sites were finally selected as candidates for allocation of hybrid solar-wind power stations.

Predicting the potential suitable habitats of forest spices Piper capense and Aframomum corrorima under climate change in Ethiopia

AbstractContinuing climate change may cause shifts in the adaptive ranges of plant species. But this impact is less understood for many species in the tropics. Here, we examined the distribution of the current and future potential suitable habitats of two native forest spices Piper capense and Aframomum corrorima. We have used MaxEnt software to predict the current and future suitable habitats of these species. Two future climate change scenarios, that is, middle (Representative Concentration Pathway [RCP 4.5]) and extreme (RCP 8.5) scenarios for years 2050 and 2070, were used. A total of 60 and 74 occurrence data of P. capense and A. corrorima, respectively, and 22 environmental variables were included. The effects of elevation, solar radiation index (SRI) and topographic position index (TPI) on suitable habitats of these species were tested using linear model in R. Precipitation of the driest quarter, SRI and TPI significantly affect future suitable habitats of P. capense and A. corrorima. Furthermore, there are significant elevational shifts of suitable habitats for both species under future scenarios (P < 0.001). These novel suitable habitats are located in moist Afromontane and Combretum-Terminalia vegetations. Our results suggest that conservation planning for these species should consider climate change factors including assisted migration.

Vitamin D and Cancer: An Historical Overview of the Epidemiology and Mechanisms.

This is a narrative review of the evidence supporting vitamin D’s anticancer actions. The first section reviews the findings from ecological studies of cancer with respect to indices of solar radiation, which found a reduced risk of incidence and mortality for approximately 23 types of cancer. Meta-analyses of observational studies reported the inverse correlations of serum 25-hydroxyvitamin D [25(OH)D] with the incidence of 12 types of cancer. Case-control studies with a 25(OH)D concentration measured near the time of cancer diagnosis are stronger than nested case-control and cohort studies as long follow-up times reduce the correlations due to changes in 25(OH)D with time. There is no evidence that undiagnosed cancer reduces 25(OH)D concentrations unless the cancer is at a very advanced stage. Meta-analyses of cancer incidence with respect to dietary intake have had limited success due to the low amount of vitamin D in most diets. An analysis of 25(OH)D-cancer incidence rates suggests that achieving 80 ng/mL vs. 10 ng/mL would reduce cancer incidence rates by 70 ± 10%. Clinical trials have provided limited support for the UVB-vitamin D-cancer hypothesis due to poor design and execution. In recent decades, many experimental studies in cultured cells and animal models have described a wide range of anticancer effects of vitamin D compounds. This paper will review studies showing the inhibition of tumor cell proliferation, dedifferentiation, and invasion together with the sensitization to proapoptotic agents. Moreover, 1,25-(OH)2D3 and other vitamin D receptor agonists modulate the biology of several types of stromal cells such as fibroblasts, endothelial and immune cells in a way that interferes the apparition of metastases. In sum, the available mechanistic data support the global protective action of vitamin D against several important types of cancer.

Analysis of Solar Ultraviolet radiation Index over Nigeria, West Africa

UV solar radiation are essential for living here on earth, however, at extreme levels, it becomes harmful to all organism with negative effects on humans due to UV-A and UV-B penetrating the earth’s surface. UV radiation index was analyzed over Nigeria, using ten years daily data extracted from the archive of the Ozone Monitoring Instrument (OMI) on-board the EOS Aura spacecraft at a coordinate of 9.08° N, 9. 67° E. The result showed that solar UV radiation is at its peak at local noon time from January 2010 to December 2019. The peak value was observed in the month of November, December, January, February, and March. Hence, the study revealed that the ultraviolet index over Nigeria's varies from high to extreme (i.e., from the Southern to the Northern regions). In conclusion, our findings will create an awareness on those regions with extreme UV radiation and measures such as using sun glasses, umbrellas and putting on protective clothes against the harmful effect of UV radiation.

Climatology and modeling of ionospheric irregularities over Greenland based on empirical orthogonal function method

This paper addresses the long-term climatology (over two solar cycles) of total electron content (TEC) irregularities from a polar cap station (Thule) using the rate of change of the TEC index (ROTI). The climatology reveals variabilities over different time scales, i.e., solar cycle, seasonal, and diurnal variations. These variations in different time scales can be explained by different drivers/contributors. The solar activity (represented by the solar radiation index F10.7P) dominates the longest time scale variations. The seasonal variations are controlled by the interplay of the energy input into the polar cap ionosphere and the solar illumination that damps the amplitude of ionospheric irregularities. The diurnal variations (with respect to local time) are controlled by the relative location of the station with respect to the auroral oval. We further decompose the climatology of ionospheric irregularities using the empirical orthogonal function (EOF) method. The first four EOFs could reflect the majority (99.49%) of the total data variability. A climatological model of ionospheric irregularities is developed by fitting the EOF coefficients using three geophysical proxies (namely, F10.7P, Bt, and Dst). The data-model comparison shows satisfactory results with a high Pearson correlation coefficient and adequate errors. Additionally, we modeled the historical ROTI during the modern grand maximum dating back to 1965 and made the prediction during solar cycle 25. In such a way, we can directly compare the climatic variations of the ROTI activity across six solar cycles.

Projected Impact of Climate Change on Habitat Suitability of a Vulnerable Endemic Vachellia negrii (pic.serm.) kyal. & Boatwr (Fabaceae) in Ethiopia

Species tend to shift their suitable habitat both altitudinally and latitudinally under climate change. Range shift in plants brings about habitat contraction at rear edges, forcing leading edge populations to explore newly available suitable habitats. In order to detect these scenarios, modeling of the future geographical distribution of the species is widely used. Vachellia negrii (Pic.-Serm.) Kyal. & Boatwr. is endemic to Ethiopia and was assessed as vulnerable due to changes to its habitat by anthropogenic impacts. It occurs in upland wooded grassland from 2000–3100 m.a.s.l. The main objective of this study is to model the distribution of Vachellia negrii in Ethiopia by using Maxent under climate change. Nineteen bioclimatic variables were downloaded from an open source. Furthermore, topographic position index (tpi), solar radiation index (sri) and elevation were used. Two representative concentration pathways were selected (RCP 4.5 and RC P8.5) for the years 2050 and 2070 using the Community Climate System Model (CCSM 5). A correlation analysis of the bioclimatic variables has resulted in the retention of 10 bioclimatic variables for modeling. Forty-eight occurrence points were collected from herbarium specimens. The area under curve (AUC) is 0.94, indicating a high-performance level of the model. The distribution of the species is affected by elevation (26.4%), precipitation of the driest month (Bio 14, 21.7%), solar radiation (12.9%) and precipitation seasonality (Bio15, 12.2%). Whereas the RCP 8.5 has resulted in decrease of suitable areas of the species from the current 4,314,153.94 ha (3.80%) to 4,059,150.90 ha (3.58%) in 2050, this area will shrink to 3,555,828.71 ha in 2070 under the same scenario. As climate change severely affects the environment, highly suitable areas for the growth of the study subject will decrease by 758,325 ha. The study’s results shows that this vulnerable, endemic species is facing habitat contraction and requires interventions to ensure its long-term persistence.

Forecasting of Energy Production for Photovoltaic Systems Based on ARIMA and ANN Advanced Models

Accurate forecasting of solar energy is essential for photovoltaic (PV) plants, to facilitate their participation in the energy market and for efficient resource planning. This article is dedicated to two forecasting models: (1) ARIMA (Autoregressive Integrated Moving Average) statistical approach to time series forecasting, using measured historical data, and (2) ANN (Artificial Neural Network) using machine learning techniques. The main contributions of the authors could be synthetized as follows: (1) analysis and discussion of the experimental and simulated results regarding solar radiation forecast, as well as energy production prediction and forecasting based on ARIMA and ANN models for two case studies: (a) laboratory BIPV system developed at the Polytechnic University of Bucharest and (b) large PV park placed in a specific site of the south of Romania. A variability index of solar radiation was introduced for the model improvement; (2) comparison between the ARIMA and ANN results to highlight the ARIMA model which is more efficient than the ANN one; (3) optimized method defined by the GMDH model (Group Method of Data Handling) proposed to provide a software program for calculation of the PV energy production.

How the global health security index and environment factor influence the spread of COVID-19: A country level analysis

The progress of viral diseases such as the new coronavirus (COVID-19) can be influenced not only by social isolation policies, but also by climatic factors. Understanding how these factors affect the progress of the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be essential to know the risks each country is facing because of the disease. In this study, we verified the existence of a relationship between the basic reproduction number (R0) of SARS-CoV-2 with different climate variables, while also considering the Global Health Security Index (GHS). We collected data from confirmed cases of COVID-19 along with their respective GHS notes and climate data, from December 31, 2019 to April 13, 2020, for 52 countries. The generalized additive model (GAM) was applied to explore the effect of temperature, relative humidity, solar radiation index, and GHS score on the spread rate of COVID-19. The countries that showed similarity to each other were grouped into clusters using the Kohonen self-organizing map methodology to investigate the importance of each variable in the dissemination of the disease. The temperature variable presented a linear relationship (p < 0.001) with the R0, with an explained variation of 36.2%, while the relative humidity variable did not present a significant relationship with the R0. The response curve of the solar radiation variable presented a significant nonlinear relationship (p < 0.001) with an explained variation of 32.3%. The GHS index variable, with a significant nonlinear relationship (p < 0.001), presented the largest explanatory response in the control of COVID-19, with an explained variation of 38.4%; further, it was observed that the countries with the largest GHS index scores were less influenced by climate variables.

Potabilização de água salobra por meio de um dessalinizador solar portátil com refletores de radiação integrados

Um dessalinizador solar portátil com refletores de radiação integrados foi utilizado com o intuito de obter uma água tratada conforme os padrões de potabilidade para o consumo humano. Este trabalho teve como objetivo analisar o desempenho térmico do dessalinizador solar para produção de água dessalinizada e a qualidade físico-química da água antes e após o processo de dessalinização. A água salobra foi coletada no poço no Sítio Poço de Pedra, no município de Juazeirinho – PB. Foi observado uma produção máxima de água potável de 2730,8 mL m-2 dia-1 para um índice de radiação solar média de 660,42 W m-2. Os resultados obtidos das análises físico-químicas das águas salobra e dessalinizada apresentaram reduções no teor de cloreto de 99,72%, o sódio de 99,88% e nos sólidos totais dissolvidos de 99,73% após o processo de dessalinização, atingindo valores de acordo com os padrões de potabilidade exigidos pela Portaria do Ministério da Saúde vigente no país.

Determination of the optimal solar photovoltaic (PV) system for Sudan

Electricity access in Africa is a major challenge in rural areas. Despite considerable potential for the use of solar energy, investments in renewable energy projects are minimal due to poor promotion of solar energy. As a result, many people still rely on private diesel generators, which release significant levels of pollutants, and have negative effects on both humans and the environment. Situated in the sunbelt, Sudan is one of the largest countries in Africa endowed with an extremely high solar irradiation potential. However, no work has been done in the literature with a strategic context to study specifically the feasibility of renewable energy systems in Sudan despite the abundance of solar resource. The aim of this study was to utilize Hybrid Optimization Model for Electric Renewables (HOMER) to identify the optimal solar photovoltaic (PV) system for Sudan’s conditions, identify the best locations, and analyze the costs and the pollution that might be avoided by employing a PV system in place of a diesel system. HOMER simulation results demonstrated that the optimal type of PV for Sudan is the Studer VarioTrack VT-65 with Generic PV. The utilization of a solar PV system will avoid the production of approximately 27 million kg/year of pollutants and will reduce the cost of energy to USD$ 0.08746/kWh. The optimal locations found in Sudan for utilizing solar energy were Wawa, followed by Kutum, Wadi Halfa, Dongola and Al-Goled due to their low costs of electricity, high clearness index and high levels of solar radiation. Given the recent rapid decrease in PV pricing and predictions for continued reductions, the costs of PV were varied to deliver an understanding on the impact of PV costs on the project economics. Reducing the PV costs by 25% has a significant impact; the cost of energy produced reduces in the range of USD$ 0.06697/kWh and USD$ 0.06808/kWh, while a reduction in PV costs of 50% further reduces the cost of energy, ranging between USD$ 0.05273/kWh and USD$ 0.05361/kWh in the top five locations in Sudan. The output of this study is projected to raising the potentiality awareness of renewable energy in Sudan and delivering a valuable reference regarding the optimal utilization of solar PV system in energy sector.

Estudo experimental de um dessalinizador solar do tipo bandeja com dupla inclinação para potabilização de água no semiárido paraibano

A escassez hídrica tem atingido significativamente a região nordeste do Brasil. Embora esta região não possua grande disponibilidade de água potável para o consumo humano, há águas salobras, que ao passar por processo de dessalinização tornam-se adequadas para o consumo humano. Um dessalinizador solar tipo bandeja com dupla inclinação foi utilizado com o intuito de obter uma água tratada conforme os padrões de potabilidade para o consumo humano. O objetivo deste trabalho foi analisar o desempenho térmico e a qualidade da água antes e após o processo de dessalinização. As águas brutas foram oriundas de três poços de comunidades rurais, Sítio Escurinha do Meio (Poço P1), Sítio Poço da Pedra (Poço P2) e Sítio Escurinha de Baixo (Poço P3) no município de Juazeirinho – PB. Foi observado uma produção média de água potável de 1583,3 mL.m-2.dia-1 para um índice de radiação solar média de 1.005,4 W.m-2. Os parâmetros físico-químicos da água bruta e dessalinizada foram monitorados, ocorrendo reduções significativas, principalmente no teor de sódio de 98,33%, 99,92% 97,83% e na condutividade elétrica de 97,79%, 99,13% e 97,69%, para os poços P1, P2 e P3 respectivamente.

Experimental Comparison of Passive Heating/Cooling Space in Lightweight Buildings with Potential Application in Mining Camps

The total energy consumption in a house in Chile includes 30% of heating expenses, increasing to 60% in the winter period. The current energy source are fossil fuels, which can be replaced by the sun, with an efficient implementation of the use of PCM for passive cooling/heating space from solar radiation, benefiting the environment. In the north of Chile there is a solar radiation index of approximately 2750 kWh·m−2, low cloudiness and low precipitation rates, indicating an important source of energy and great opportunity for improvement in the use and management of energy resources. Moreover, mining camps present in large numbers in the northern zone require a lot of energy to cool and heat the space. This research shows the thermal behavior in summer and winter of two lightweight constructions, similar to the type used in mining camps, with dimensions of 2.5 × 2.5 × 2.5 m at pilot scale installed at the University of Antofagasta, Chile. One of these modules contains PCM on the inside of the walls and ceiling, while the other does not, to analyze the effect of PCM by comparison. The results of this work show that in winter (August) the application of PCM favors the permanence within the thermal comfort zone, with a difference of 5°C. In summer there is an opposite effect (January), experiencing a higher temperature increase inside the container with PCM, with a difference of 4°C. According to the constructive characteristics, properties and quantity of PCM used, and the effect of solar radiation on the structure and environmental conditions, there are benefits in energy saving and efficiency in the winter period, while summer shows results that enhance the study and analysis of the applied technology to solve the thermal behavior shown in this season.

Prospects of the development of the solar energy industry on the territory of the former water area of the Aral Sea

The article is devoted to the analysis of the prospects of the development of the solar energy industry in the Aral Sea region. The main purpose of the article is to identify key conditions conducive to the development of solar energy in the Aral Sea region, to assess the expected energy production by power plants located in this territory. This article is based on a set of research methods: analytical, statistical, comparative, which allowed assessing the potential energy production by solar panels. Also, the Methodology for calculating the water balance of water bodies of the Ministry of Natural Resources and Environment of the Russian Federation was used for the calculations presented in the article. The authors obtained the following results: analysis of climatic conditions and solar radiation indices made it possible to conclude that this region is characterized by a high potential for the development of solar energy, the presence of extensive mineral resources allows to form a high-tech cluster of the energy industry in the region. The development of solar energy in the territory of the former Aral Sea will have a complex positive impact on the economy, the social sphere and the environment of the Aral Sea region. The result of the implementation of projects is the creation of new jobs, attracting investment in the Aral Sea regions. The research results can be used in the development of regional and local investment promotion programs in the field of renewable energy.

LiDAR-derived topography and forest structure predict fine-scale variation in daily surface temperatures in oak savanna and conifer forest landscapes

In mountain landscapes, surface temperatures vary over short distances due to interacting influences of topography and overstory vegetation on local energy and water balances. At two study landscapes in the Sierra Nevada of California, characterized by foothill oak savanna at 276–481 m elevation and montane conifer forest at 1977–2135 m, we deployed 288 near-surface (5 cm above the surface) temperature sensors to sample site-scale (30 m) temperature variation related to hillslope orientation and vegetation structure and microsite-scale (2–10 m) variation related to microtopography and tree overstory. Daily near-surface maximum and minimum temperatures for the 2013 calendar year were related to topographic factors and vegetation overstory characterized using small footprint LiDAR imagery acquired by the National Ecological Observatory Network (NEON) Airborne Observation Platform (AOP). At both landscapes we recorded large site and microsite spatial variation in daily maximum temperatures, and less absolute variation in daily minimum temperatures. Generalized boosted regression trees were estimated to measure the influence of tree canopy density, understory solar radiation, cold-air drainage and pooling, ground cover and microtopography on daily maximum and minimum temperatures at site and microsite scales. Site-scale models based on indices of understory solar radiation and landscape position explained an average of 61–65% of daily variation in maximum temperature; site-scale models based on tree canopy density and landscape position explained 65–83% of variation in minimum temperatures. Models explained <15% of variation in microsite-scale maximum temperatures but within-site heterogeneity was significantly correlated with within-site heterogeneity in modeled understory radiation at both landscapes. Tree canopy density and slope explained 33% of microsite-scale variation in minimum temperatures at savanna sites. Our results demonstrate that it is feasible to model site-scale variation in daily surface temperature extremes and within-site heterogeneity in surface temperatures using LiDAR-derived variables, supporting efforts to understand cross-scale relationships between surface microclimates and regional climate change. Improved understanding of topographic and vegetative buffering of thermal microclimates across mountain landscapes is key to projecting microclimate heterogeneity and potential species’ range dynamics under future climate change.

Estimation of Global Solar Radiation and Clearness Index in Coast of Gulf of Guinea, Nigeria

The concept of solar energy and its applications in present day would come to be one of the solutions to our Nigerian problem of instability and epileptic power supply. In this study, data for mean monthly sunshine hours and global solar radiation for Ikeja, Lagos state capital (6.580N, 3.320E) were obtained from Nigeria Metrological Agency (NiMeT), Oshodi Lagos, Nigeria and spanned 1996 to 2010. The data for global solar radiation were measured using a Gunn-Bellani radiometer. A linear regression correlation model was developed for Ikeja and other surrounding area in south-western part of Nigeria with similar meteorological conditions. The results of estimated global solar radiation ranged from 5.1 MJm-2 day-1 on average for August and 13.1 MJm-2 day-1 for March for Lagos. The Angstrom constants a and b of Angstrom-type correlation to estimate monthly average global solar radiation was estimated to be 0.25 and 0.63 respectively. The result for global solar radiation were then subjected to statistical tests [MBE, RMSE, MPE] and proved to be good estimates. The value of clearness index was also estimated to range from 0.31 to 0.59 showing Lagos as a partly clear sky city.

Classification of Hourly Clearness Index of Solar Radiation in the District of Yamoussoukro

The exploitation of systems using solar energy as a source of energy is not fluctuations free because of short passage of clouds on solar radiation. The amplitude, the persistence and the frequency of these fluctuations should be analyzed with appropriate tools, instead of focusing on their location over time. The analysis of these fluctuations should use the instantaneous clearness index whose distribution is given as a first approximation which is independent not only of the season but also of the site. It is important to evaluate the potential solar energy in a region. Indeed such evaluation helps the decision-makers in their reflections on agricultural or photovoltaic solar projects. Then this study was conducted for a predictive purpose. The method used in our work combines the classification method which is the hierarchical ascending classification and two partitioning methods, the principal component analysis and the K-means method. The partitioning method enabled to achieve a number of well-known situations (in advance) that are representative of the day. The study was based on the data of a climatic weather station in the district of Yamoussoukro located in the center region of Cote d’Ivoire during the 2017 year. Using the clearness index, the study allowed the classification of the solar radiation in the region. Thus, it showed that only 346 days of the 365 days in 2017 were classified (95%). We identified three clusters of days, the cloudy sky (29%), the partly cloudy sky (32%) and the clear sky (39%). The statistical tests used for the characterization of these clusters will be detailed in a future study.