In this research, a multi-objective model is presented considering simulated behavior of high-efficiency rooftop Solar PV panels in a factory, which are among the largest producers of greenhouse gases. The paper proposes a simulationoptimization approach that is used to maximize the net present value (NPV) of economic benefits along with minimizing the payback period (PBP) of the investment and maximizing Solar energy consumption rate (SECR). In addition, the Solar PV panels degradation and maintenance cost, as well as the uncertainty in Solar irradiance and demand load, are also considered. The study consists of two scenarios, in the first of which both electricity tariffs and feed-in-tariffs (FiT) are fixed by a long-term contract. The second scenario investigates the situation in which subsidies on electricity tariff are removed. The best types of panels are found in each scenario considering the trade-offs between objective functions. The preferred trade-off solution in the first scenario, with a 2% increase in PBP, achieves more than 10% growth in NPV which is about $15000 in a year. In the second scenario, with only about a 0. 2% decrease in NPV and a 3% increase in PBP, the preferred solution attains a 9% increase in SECR.

The impact of Solar radiation and ambient temperature on Solar PV energy yield and its corresponding economic implication was investigated. The electrical load assessment was done by physical inspection through periodic visits to study location. Five different scenarios were investigated for two locations - Ogun and Bayelsa States: Case I considers the PV performance based on the  locations’ historical Solar radiation and temperature data, Case II considers  30 % increase in the Solar radiation data while the ambient temperature data remains fixed, Case III  focuses on when Solar radiation data is decreased by 30 % while the ambient temperature data remains constant, Case IV considers the Solar radiation data remains constant while the temperature values are  increased by 30 %, and Case V examined the same Solar radiation values with temperature data values being decreased by 30 %. The HOMER pro was used as the implementation tool, Electrical energy yield, Unmet electric load, Net present cost, Levelized cost, and Operating cost for Cases I, II, III, IV, and V in Ota, Ogun State were as follows: 28,659 kWh/y, 4.71kWh/y, $13,537, $0.166, 271.43kWh/y; 37,260 kWh/y, 1.63kWh/y, $12,417, $0.152, 290.43kWh/y; 20,058kWh/y, 3.22kWh/y, $15,663, $0.192, 293.14kWh/y; 28,659kWh/y, 4.71kWh/y, $13,537, $0.166, 271.43kWh/y; and 28,659kWh/y, 4.61kWh/y, $13,437, $0.156, 261.43kWh/y, respectively while similar trend was observed for Otuasega in Bayelsa State. The results of the analysis showed that the optimal performance of the PV module occurred at a higher Solar radiation and a lower ambient temperature.

Solar radiation is an important parameter in the study of electricity and/or thermal system installation. Direct monthly irradiance data measurements of the earth’s horizontal surface irradiance for the year 1985 to 2019 for nine stations (Sokoto, Birnin Kebbi, Maiduguri, Ilorin, Calabar, Port-Harcourt, Enugu, Iwo, and Ikeja) were collected from the achieve of HelioClim satellite website. The stationarity of the series was determined using the time plot of the irradiance data between the periods under study but the formal test of stationarity was carried out using the Augmented Dickey-Fuller (ADF) test with a p-value less than 0.05 signifying stationarity.  Different autoregressive integrated moving average (ARIMA) models were fitted to the irradiance data for each of the selected stations.  The results revealed that Sokoto, Maiduguri, and Kebbi have their maximum Solar irradiance at about  and their minimum at about , while Ilorin has its maximum Solar irradiance at about  and its minimum Solar irradiance at about . Ikeja, Iwo and Port-Harcourt, Calabar and Enugu have their maximum Solar irradiance  and their minimum Solar irradiance at about . It is therefore concluded that for Kebbi, Iwo and Maiduguri, the best model was ARIMA (3,0,3), for Calabar and Sokoto, it was ARIMA (2,0,2) while for other locations like Enugu, Ikeja, Ilorin and Port Harcourt, ARIMA (2,0,3) was the best model for forecasting irradiance in these study areas. The forecasted values of irradiance between January till December 2020 with its corresponding 95% confidence levels indicate good prediction of Solar irradiance for future occurrence.

The temporal variation in the direct normal irradiance, diffuse horizontal irradiance, global horizontal irradiance, and ambient temperature was quantified during the 21 August 2017 Solar eclipse. The magnitude and obscuration of the eclipse at the observation location were 0. 97 and 96. 94%, respectively. A two-axis sun tracker equipped with a pyrheliometer, a shaded pyranometer, an unshaded pyranometer, and a pyrgeometer were utilized to obtain the Solar irradiance measurements. Thermistors contained within the pyrheliometer and the pyrgeometer were used to quantify changes in temperature. Unfortunately, on the day of the eclipse, the weather conditions were not ideal and periodic cloud coverage impacted measurements of the direct normal irradiance. As such, Solar irradiance and temperature data from 2 days prior, when the weather conditions were near-ideal, are presented for comparison. The temperature of the air as measured by the thermistors enclosed within the pyrheliometer and pyrgeometer recorded an average temperature drop of 8. 49 ° C. The minimum temperature was recorded approximately 47 min after totality. The diffuse horizontal irradiance reached a maximum value of 495. 9 W/m2 shortly after the start of partial eclipse and dropped to a minimum value of 0 W/m2 near totality. Similarly, the global horizontal irradiance reached a maximum value of 1138 W/m2 and dropped to a minimum value of 1. 54 W/m2 near totality. For reference, at the same time of day, but 2 days prior, the diffuse horizontal irradiance and global horizontal irradiance were at values of 89. 2 W/m2 and 962 W/m2, respectively, under clear sky conditions. The rate of decrease in the temperature of the air as well as in the diffuse and global horizontal irradiances after first contact and before totality was greater than the rate of increase in these parameters after totality. The difference in the magnitude of these gradients before and after totality is largely attributed to normal diurnal variations as the Solar eclipse occurred in the afternoon.

The use of concentrating Solar collectors which are used in Solar thermal power plant and concentrated photovoltaic systems implies that these systems only work with the direct normal irradiance (DNI). Unfortunately, DNI ground-based measurements are rarely available at the location of interest, this lack of DNI data contrasts with the availability of global and diffuse horizontal irradiance data (GHI, DHI). Nowadays, several spatial databases that estimate DNI have been developed; however, these databases present uncertainty and provide different values of DNI. In this present study, a proposed methodology for estimating the hourly, monthly mean daily, monthly and annual direct normal irradiance DNI in the presence or absence of measured global and diffuse horizontal irradiances. When applying the proposed method for calculation of DNI for three Algerian ground stations (Algiers, Ghardaia, and Tamanrasset), we obtained better performances than those of the five spatial databases’ data, especially for the monthly values. The methodology seems to give a very appropriate way for management and exploitation of DNI resources for the design and analysis of concentrating photovoltaic and thermal systems; and can be applicable to other worldwide locations using empirical equations with new correlation coefficients for estimating direct normal irradiance.

The extraterrestrial radiation is the Solar radiation received at the top of the earth’s atmosphere on horizontal surface. This quantity over selected stations in the tropics was investigated. Daily data of the extraterrestrial radiation on the earth horizontal surface for the year 2018 for stations: Iwo, Abuja, Enugu, Port-Harcourt, Sokoto and Maiduguri obtained from the archive of HelioClim website were analyzed using MATLAB and Statistical Packages for Social Science (SPSS Version 20.0) to estimate the extraterrestrial radiation of the station considered. The results of the MATLAB revealed that the value of the coincidence is  across all stations. In January, the values between 15 - 20 peaks were observed in the year with the Irradiation ( ) and the maximum ( ). The results revealed the Root Mean Square Error RMSE for Sokoto (139.99), Abuja (162.72), Iwo (177.07), Maiduguri (171.34), Enugu (191.07), Port-Harcourt (212.27). The results also revealed that quadratic trend equation which accounted in the range 95.9% - 41.9%. The results then concluded that Sokoto and Maiduguri have the highest Solar irradiance as revealed by the result.