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The cost of manufacturing and electricity consumption are key considerations in encouraging the adoption of solar air heaters (SAH) in sunny and low‐income areas. These parameters can have a significant impact on promoting the use of these devices. In this study, solar air heating was designed with the objective of achieving the highest possible efficiency/cost ratio. It is a corrugated channel SAH whose structure is equipped with two barriers perforated with a sufficient number of holes for a good airflow distribution. A new model was developed to evaluate the qualitative parameters that describe the thermos‐energetic behavior of a heating system. These parameters were measured using experimental data obtained under real operating conditions. The thermal model assumes a uniform temperature for the glass, absorber, and insulation of the collector, while the temperature of the circulating air is assumed to vary linearly along the collector. To ensure that these assumptions were valid, the collector was cut into a number of 0.1 m sections in the direction of flow. By comparing the numerical results with the experimental data, the model was validated and then used to calculate the temperature profiles of the different elements of the collector, as well as to estimate the impact of certain operational parameters on its thermal performance. Relative percentage error values, between the numerical and the experimental results, of 1.7517%, 1.0750%, 0.8577%, 2.2371%, and 2.3637% for absorber plate temperature, outlet airflow temperature, useful power, thermal, and effective efficiencies, respectively, are recorded. [ABSTRACT FROM AUTHOR]

This paper presents a bibliometric analysis of scientific research on renewable energy in Africa, a rapidly growing field driven by the need for sustainable and accessible energy solutions. It highlights Africa's role as a hub for renewable energy innovation, with local researchers collaborating with global institutions to address the continent's unique energy challenges. This synergy is enhancing energy access in African communities and contributing to the global advancement of renewable technologies. The study meticulously examines 3,109 scientific publications from the Scopus database, spanning from 1979 to 2022. It analyzes the evolution, geographical distribution, and impact of these publications, with a focus on international collaborations and scientific output. Findings indicate that South Africa leads in productivity with 962 publications and hosts the top affiliating institutions in this domain. The study also reveals an exponential increase in renewable energy research, particularly from South Africa, the United States, and the United Kingdom, emphasizing the need for more collaborative efforts and knowledge exchange globally. This analysis provides critical insights into the current landscape of renewable energy research and pinpoints areas ripe for further exploration and development in this vital sector. [ABSTRACT FROM AUTHOR]

The performance of photovoltaic (PV) modules is affected by the increase in their operating temperature. Accurate and reliable prediction of the PV module operating temperature (TM) is useful for evaluating their electrical performance and productivity and predicting the maximum power point under changing weather conditions. Based on experimental measurements collected during 1 year by a station placed in a semi-arid coastal region, in Morocco, several models are investigated to predict TM of polycrystalline PV modules. Starting from existing models in the literature, models have been developed to improve the accuracy of their prediction in the studied climate. The results show that irradiance (G) and ambient temperature are the most influential parameters for estimating the TM of the studied PV module. The accuracy of the prediction can be improved by introducing the effects of Vw and RH in the proposed models. In addition, using the physical parameter extraction results of the studied modules, equations are established to approximately predict their behavior as a function of TM and G. Taking into account the proposed TM models, these equations describing the physical parameter evolution can constitute an important basis for predicting PV module performance under real operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents the design of highly efficient rectifiers that can operate at WiFi frequencies (2.45 GHz and 5.8 GHz) and match low input power. The designed dual-band rectifiers use multi-stage dickson voltage multipliers (DVM) (from 1 to 6 stages), and the main idea of this paper is to find the number of stages that offers the best performance and that can be used by applications that operate within the same constraints (operating frequencies, input power). The efficiency and the output voltage (Vout) are the parameters studied to analyze the designed rectifiers. The results showed that as the number of DVM stages increased, the efficiency curves for both frequencies shifted to the higher input power range, even when using the same diode (SMS7630) and the same load (5 KO). We concluded that the rectifier with 1-stage DVM is the most suitable to be used for low input power at the selected frequencies since it provides an efficiency of 57.734% at 0 dBm for 2.45 GHz and 36.225% at 1 dBm of input power for 5.8 GHz. [ABSTRACT FROM AUTHOR]

In this paper, a study on photovoltaic module physical parameters behavior depending on irradiance G and module temperature TM is presented. From this investigation, new equations translating physical parameters behavior depending on TM and G are developed. The new proposed laws, which combine the effects of G and TM in a correlated manner, have the advantage of incorporating G effect on the temperature coefficients by including specific terms. The developed laws form a basis for predicting PV module performance and can be incorporated into maximum power point tracking (MPPT) programs to extract peak power output under different operating conditions. This study is conducted by examining the electrical performances at the maximum power (Im, Vm), the open circuit (0, VOC), and the short circuit (ISC, 0) points measured using an elaborate experimental platform. The photovoltaic module used is a monocrystalline type exposed to four G values of 700, 800, 880 and 1000 W.m-2 for temperatures TM between 16°C and 48°C. [ABSTRACT FROM AUTHOR]

In this manuscript, we have theoretically reanalyzed data prepared and already published by Foroughi et al. (RSC Adv 2016;6:46427–32). These data concern the thermal energy dependence of the electrical conductivity of the samples: graphene fiber, graphene/poly(3,4-ethylenedioxythiophene) (graphene/PEDOT), graphene/carbon nanotube (graphene/CNT) and graphene/carbon nonotube/poly(3,4-ethylenedioxythiophene) (graphene/CNT/PEDOT) composite fibers. We investigate the behavior of the thermal conductivity for these four samples. These samples are considered as thermoelectric materials or green energy conversion materials using the Seebeck effect to transform heat into electrical energy and vice versa. In this context, the optimization of the merit factor ZT remains a challenge for the scientific community. The objective of this investigation is to evaluate and characterize the thermoelectric efficiency of the above-mentioned samples. We confront the experimental data with the existing theoretical models. The thermoelectric efficiency is generally characterized by the merit factor ZT. The maximum ZT of about 1,2 is obtained in the graphene fiber and between 0,1 and 0,2 in the others samples. The performance of the material depends on ZT; indeed a high ZT (⁠|$\mathrm{ZT}\ge 1$|⁠) corresponds to a better optimization of the composite. [ABSTRACT FROM AUTHOR]

The islanding of grid-connected photovoltaic (PV) installations is a difficult problem that leads to many protection and security problems. A variety of islanding detection methods (IDMs) are proposed in several studies and these techniques are categorized into passive, active and communication based methods. This study describes the IDM adopted to detect islanding situation in the new PV installation connected to LVs grid of OCP Group (Cherifian Office for Phosphates in Morocco), global leader in the phosphate and phosphate derivatives markets. After having defined the way in which the PV generators will be integrated within the OCP Group grid, the causes that could lead to islanding situation are established. The comparison on the most used methods for islanding detection in the grid connected photovoltaic system (PV) is based on three parameters: the Non-Detection Zone (NDZ), the Detection Duration Time (DDT) and Total Harmonic Distortion (THD) of each method. These performance criteria are compared with the limit thresholds authorized by the IEEE 1574 standard, which are 5% for THD and 2 seconds for DDT. The Slip Mode Frequency Shift (SMS) method is demonstrated to be the most effective, for our installation, among the simulated methods, with THD and DDT of 1.3% and 0.28s, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a new method of modeling PV modules in the Pspice simulator is proposed. This method consists in describing the behaviour of PV modules and the evolution of their I-V characteristics as a function of the temperature and the solar irradiance. The developed modelling technique is based on the internal physical parameters (photogenerated current (Iph), saturation current (Is), ideality factor (n) of the diode, series resistance (Rs) and shunt resistance (Rsh)) extracted using a high performance extraction method based on the experimental characteristics of the studied module. Experimental measurements of I-V characteristics were taken, under real operating conditions, using a high-precision I-V curve plotter. The values of these parameters are injected into the single diode model established under the Pspice simulator. This technique allows to construct with satisfactory simplicity the I-V curve of different PV module technologies under different environmental conditions. The comparison of simulation results and those obtained experimentally shows the accuracy of the used method. Furthermore, based on measured data, extracted saturation current, series resistance and ideality factor seem to be not influenced by the variation of the irradiance. Then, the comparison of the extracted parameters with those calculated by empirical laws proposed in literature, shows the reliability of these laws and this for the studied monocrystalline PV module. Moreover, it has been studied, experimentally and with empirical laws, the evolution of the efficiency and the power, of the studied PV module, as a function of the temperature. It appears that the rise of temperature from 25° C to 55° C deals with an electrical efficiency drop of about 2.2 %. [ABSTRACT FROM AUTHOR]