Different configurations of on/off-grid-connected hybrid renewable energy systems (HRESs) are analyzed and compared in the present research study for optimal decision making in Sub-Saharan Africa, facing the problems of electricity deficit. A multi-criteria analysis is performed for this purpose using MATLAB software for simulation. The obtained results show that the levelized cost of energy (LCOE) corresponding to 0% power supply deficit probability (PSDP) is 0.0819 USD/kWh, 0.0925 USD/kWh, 0.3979 USD/kWh, 0.3251 USD/kWh, 0.1754 USD/kWh, 0.1641 USD/kWh, 0.5385 USD/kWh, and 1.4515 USD/kWh, respectively, for the Grid-PV/Wind/Battery, Grid-PV/Battery, Grid-Wind/Battery, Grid-Wind, PV/Wind/Battery, PV/Battery, Wind/Battery, and stand-alone Wind systems. The CO₂ emissions are 14,888.4 kgCO₂/year, 16,916.6 kgCO₂/year, 13,139.7 kgCO₂/year, 6430.4 kgCO₂/year, 11,439 kgCO₂/year, 14,892.5 kgCO₂/year, 10,252.6 kgCO₂/year, and 1621.5 kgCO₂/year, respectively, for the aforementioned systems. It is found that the Grid-connected PV/Wind/Battery is the most cost-effective system leading to a grid energy cost reduction of 30.89%. Hybridization of different renewable energy sources (RESs) could significantly improve the electricity cost and reduce the CO₂ emissions. However, this improvement and this reduction depend on the used RES and the system configuration. On-grid-connected HRESs are more cost-effective than off-grid-connected HRES. The least polluting energy system is the stand-alone Wind system, which allows a reduction in the grid CO₂ emissions by 93.66%. The sensitivity analysis has proven that the long-term investment, the decrease in the battery cost, and the decrease in the discount rate could lead to the reduction in the LCOE.

Extending the public electricity grid to rural or peri-urban areas is sometimes very costly and unprofitable due to their remoteness, low population density and sometimes difficult accessibility. In view of this, and in the concern of a sustainable development, the autonomous PV and/or wind power systems is increasingly used. However, these fluctuating source systems remain unreliable due especially to their intermittent nature, what justifies the integration of battery storage systems to them. They are also still expensive, particularly in the African context, limiting their access to the greatest number of the population. In addition to these problems of cost and reliability, the issue of optimal sizing of such systems is essential. In this paper, energy storage technologies, performance criteria, basic energy production and storage models, configuration types, sizing and management techniques discussed in the literature for the study of stand-alone solar and/or wind power systems in isolated sites are reviewed. The findings of the present study reveals that electrochemical battery is the main technology used for energy storage in stand-alone PV-wind systems due in particular to their maturity compared to the other storage technologies. However, it also shows that while batteries are the most widely used energy storage technology for solar and wind power systems, they are still expensive. The paper also revealed that traditional methods of optimal sizing and management of autonomous solar and wind power generation systems are being used less and less, in favor of artificial intelligence methods, due mainly to their limited flexibility and inability to solve complex problems.

This work presents the regulation of temperature in an indirect multitrays solar dryer with oriented flux under the irradiance fluctuation. The temperature regulator using a negative temperature coefficient (NTC) as a sensor and fans is designed, and a similar device is also used to measure humidity through a sensor. Inlet and outlet dryer temperature and temperature on the three trays have been recorded with the regulation system according to different airflow modes. Irradiance and humidity have also been recorded. The model of outlet temperature with energy storage was given by using heat transfer equations. The results have shown that in the linking airflow mode, the average temperature on the three trays is 51.3±1.5^a°C, 52.18±1.4^a°C, and 51.9±1.2^a°C, respectively, with 52°C as setpoint temperature and NTC fixed on tray number 2. With temperature sensor in the same tray and 51°C as setpoint temperature, the average temperatures on the three trays are 51.86±1.54°C, 51.60±1.16°C, and 50.42±1.13°C, respectively, in mixed mode, whereas in crossing airflow mode, the temperature gradient does not allow regulation on all trays. The regulation is possible when the temperature in the dryer chamber exceeds the set point temperature by more than 5. The proportional type corrector is suitable for the temperature controller in indirect solar dryers. When the energy source is unstable, humidity which is a variable parameter is used to mark the end of drying instead of time.

The purpose of the present work is to investigate transient behaviour of a parabolic trough solar collector in the climate conditions of Sahel through the energetic and exergetic analysis. An unsteady state approach of the first and second law of thermodynamic is applied on the heat collector element. The Finite Volume and Gauss quadrature methods, and Tri-Dimensional Matrix Algorithm were used as computational methods. Synthetic oil was considered as thermal fluid. The incident solar radiation and solar radiation availability were estimated respectively by Capderou and Petela models for different tracking modes. Furthermore, the optical, thermal and exergetic fluxes and efficiencies were computed. Based on numerical results, it was concluded that, by realising 14.04 GJ/m(2), 71.62%, 71.47% and 9.08%, respectively the annual solar irradiance, optical, thermal and exergetic efficiencies, the polar East-West is the suitable one axis tracking mode. The decrease of the collector's thermal efficiency is monotonous with inlet temperature of fluid, while his transient exergetic efficiency varies toward an optimum point over the year,, corresponding to 150 degrees C.

The depletion of fossil energy and his consumption in cooking as the use of firewood are contributing to increase the problem of climate change. It is urgent to find alternative energy sources to take over the situation when the areas are being blessed with higher solar energy potential. The present work concerns design and realization of a mixed solar cooker. It consists of a parabolic reflector of 1m diameter and 0.24m focal point and a box type size of 8.064 dm3. The temperature and irradiance measurements were carried out using a pyranometer and PT 100 sensors. The data were recorded using an acquisition unit (ALMEMO 2390). The design was made by a basic theoretical model developed from the heat transfer equations and simulated using MATLAB software. The tests carried out show that without a sun tracking and without regulating, the temperature inside the cooker rises and reaches the maximum of 95.5°C for a day during which the average irradiance is 690.13 W⁄m2. Without temperature regulation and with manual sun tracking, the temperature is not constant and the maximum value obtained in the cooker is 168°C for an average irradiance of 716.86 W⁄m2. The cooking of 2 litres of sorghum wort was carried out through manual temperature regulation of 80°C for 1 hour and 16 minutes under an average irradiance of 555.52 W⁄m2.