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For silicon solar cells simulation studies, one dimensional (1D), two dimensional 2D) and t hree dimensional (3D) models are used. Depending of model proposed and assumptions done for the study, the electronic and electrical parameters and then the performance of the solar cell can be influenced. This situation raises the problem of the relevance of the choice of the study model and the quality of the resulting results. This work, propose comparative study of the electronic and electric parameters of 1D model, 3D analytical model and 3D empirical model. In this study, continuity equations of excess minority electrons are solved for 1D and 3D models and analytical expressions of electronic parameters (density of electrons δ, intrinsic junction recombination velocity Sf0 and recombination velocity at back surface Sb) and electric parameters (Jsc, Voc, η) are derived. The influence of the model chosen on the electric and electronic parameters of the PV cell have been presented. It appears in this study that the choice of the simulation model has a large influence on the electronic and electrical parameters the PV cell. The one-dimensional formulation (1D) overestimates the solar cell efficiency comparatively to the three-dimensional (3D) formulations. The study put in evidence also that for the same grain size, the solar cell efficiency resulting of 3D classical formulation is overestimates than one resulting of 3D empirical formulation.

This paper is an assessment of radiative forcing caused by atmospheric aerosols in an urban city in West Africa. It is carried out in Ouagadougou in Burkina Faso and is an illustration of the radiative impact in most of the large Sahelian urban cities which are under the same climatic influences and whose populations present similarities in their socio-economic aspects. Using the GAME code, the radiative forcing was calculated at the top of the atmosphere, in the atmospheric layer and at the earth’s surface. The results showed overall a cooling effect at the top of the atmosphere due to the backscattering in space of the incident radiation, a heating in the atmospheric layer due to the absorption effect and a surface cooling justified by the attenuation of radiation crossing the atmosphere. Using monthly average values of optical properties, vertical temperature and humidity profiles, daily temperatures and surface albedo, the simulation yielded forcing values ranging from -6.77 W/m2 to -2.56 W/m2 at the top of the atmosphere, from 15.8 W/m2 to 34.7 W/m2 in the atmospheric layer and from -41.00 W/m2 to -21.68 W/m2 at the earth’s surface. In addition, the warming was simulated in the first atmospheric layer (in contact with the surface), and the results show values ranging from 0.8°C to 1.8°C. The study of the annual variability of the results showed a strong correlation between the radiative forcing and the seasonal succession characteristic of the climate in West Africa with the extreme values in the month of March (characteristic of the dry and hot season) and in the month of August (characteristic of the rainy season).

It is well known that temperature acts negatively on practically all the parameters of photovoltaic solar cells. Also, the solar cells which are subjected to particularly very high temperatures are the light concentration solar cells and are used in light concentration photovoltaic systems (CPV). In fact, the significant heating of these solar cells is due to the concentration of the solar flux which arrives on them. Light concentration solar cells appear as solar cells under strong influences of heating and temperature. It is therefore necessary to take into account temperature effect on light concentration solar cells performances in order to obtain realistic results. This one-dimensional study of a crystalline silicon solar cell under light concentration takes into account electrons concentration gradient electric field in the determination of the continuity equation of minority carriers in the base. To determine excess minority carrier’s density, the effects of temperature on the diffusion and mobility of electrons and holes, on the intrinsic concentration of electrons, on carrier’s generation rate as well as on width of band gap have also been taken into account. The results show that an increase of temperature improves diffusion parameters and leads to an increase of the short-circuit photocurrent density. However, an increase of temperature leads to a significant decrease in open-circuit photovoltage, maximum electric power and conversion efficiency. The results also show that the operating point and the maximum power point (MPP) moves to the open circuit when the cell temperature increases.

In earlier studies, we have shown theoretically and experimentally that magnetic fields (MFs) have negative impact on silicon PV module (photovoltaic module). A noticeable decline in photocurrent with a slight increase in photovoltage was observed. Also, how those fields affected other key module’s parameters was also studied. These studies concluded that an increase in the magnitude of the MF resulted in the decrease of the efficiency of the silicon PV module. The previous experimental studies assumed that the MF vector formed zero angle of inclination with respect to the photosensitive face of the module. They did not factor in any effect that could be observed when the field vector is inclined. The present experimental work is an attempt to fill that gap. The characteristic curves of the PV module were plotted in the same system of axis for different values of the inclination angle of the MF vector. Correspondingly, the characteristic values ( P max , I max , V max , I sc , and V oc ) of the PV module were also determined. These parameters then allowed the calculation of the efficiency of the module, its fill factor, and the equivalent circuit series and shunt resistances. It is observed that the module efficiency increases with the inclination of the MF vector, indicating that the effect of the MF on the PV module is reduced when its vector aligns towards a direction that is perpendicular to the base of the module. For example, when α moves from 0 to 90°, the power output and consequently the efficiency of the PV module relatively increase of 14%.

This paper investigated, by one-dimensional modelling, the effects of reverse polarisation of an electromagnetic field, generated by an amplitude modulation radio antenna, on the efficiency of a silicon PV cell. Through a simulation, the effects of both the incidence angle and the electromagnetic field magnitude on the power output of the PV cell are analyzed. The power output curves against the junction dynamic velocity are used to find the junction dynamic velocity at the equilibrium, the maximum power output, and the efficiency of the PV cell. The results have shown that the presence of important electromagnetic fields in the neighborhood of a silicon PV cell decreases its performance.

The increasing cohabitation between telecommunication antennas generating electromagnetic waves and solar panels poses the problem of interaction between these radio waves and solar cells. In order to study the effect of radio waves on the performance of a polycrystalline silicon solar cell in a three-dimensional approach, it is necessary to assess the attenuation of the radio wave in the illuminated polysilicon grain and also to find the expressions of its components. This work investigated the attenuation of radio waves into a polycrystalline silicon grain by analyzing, firstly, the behaviour of the penetration length of the radio waves into the polysilicon grain and secondly, the behaviour of the attenuation factor. The propagation of the radio waves into the polycrystalline silicon grain can be considered without attenuation that can be neglected.

The objective of this work is to study the diurnal evolution of the radiative impact of atmospheric aerosols in an urban city located in the West African Sahel and the correlations with the main influencing factors of local climate dynamics. The simulation was performed using a treatment chain including the GAME code. In the methodology, the atmosphere is modeled by 33 plane parallel layers and the effects of absorption, multiple scattering by particles and gas are taken account. An hour-by-hour calculation of radiative forcing at the top of the atmosphere, in the atmospheric layer and at the earth’s surface was performed. The data used as input are the monthly averages of optical properties, radiosonde measurements, daily synoptic measurements and surface albedo. The results show a parabolic diurnal course of a negative radiative impact at the top of the atmosphere with an extremum at 12 o'clock. Maximum cooling is observed shortly after sunrise and shortly after sunset. The largest annual deviations are noted between the months of March and December with respective maximum cooling values of -34 W/m2 and -15.60 W/m2. On the earth’s surface, a cooling impact is observed with two diurnal peaks at sunrise and sunset, the greatest difference between the diurnal maximums is noted between March (-104.45 W/m2) and August (-54 W/m2). In the atmospheric layer, there is almost constant diurnal warming between 9 a.m. and 4 p.m. The maximum difference between the diurnal extremes is also noted between March (about 85 W/m2) and August (35 W/m2). Likewise, the study of the diurnal warming of the first atmospheric layer showed the extreme values in March (5.6°C) and August (2.4°C), these maximum values being always observed at around 12 o’clock. An analysis of similar works carried out in urban cities in various locations of the world has shown a relatively good accordance with the values obtained. This study highlights the radiative impact of Saharan desert dust, the effect of the local climate and the succession between dry season (November to May) and the rainy one (July to October), as well as the zenith solar angle and human activity.

In this work, a one dimensional approach is presented for modelling the effect of the incidence angle, varying from 0 rad to π/2 rad, and the intensity of radio waves on the performance of a polycrystalline silicon solar cell under constant multispectral illumination. By solving the continuity equation in steady state, we derived the expression of the density of excess minority carriers, the photocurrent density, the photovoltage, the electric power and their dependence on the incidence angle and the intensity of the electromagnetic field is analyzed. Using the electric power curves versus junction dynamic velocity we determined the electric power lost at the junction, the maximum electric power and we calculated the conversion efficiency for various incidence angle and intensity of the electromagnetic field. The leakage photocurrent density, deduced from the photocurrent density curves versus junction dynamic velocity, and the electric power lost at the junction allowed us to calculate the shunt resistance of the solar cell according to the incidence angle and the intensity of the electromagnetic field. The numerical data show the negative effect of radios waves on the performance of a silicon solar cell.

The efficiency of a silicon solar cell is directly linked to the quantity of carrier photogenerated in its base. It increases with the increase of the quantity of carrier in the base of the solar cell. The carrier density in the base of the solar cell increases with the increase of the flux of photons that crosses the solar cell. One of the methods used to increase the flux of photon on the illuminated side of the solar cell is the intensification of the illumination light. However, the intensification of the light come with the increase of the energy released by thermalization, the collision between carriers, their braking due to the carriers concentration gradient electric field which lead to increase the temperature in the base of the solar cell. This work presents a 3-D study, of the effect of the temperature on the electronic parameters of a polycrystalline silicon solar under intense light illumination. The electronic parameters on which we analyze the temperature effect are: the mobility of solar cell carriers (electrons and holes), their diffusion coefficient, their diffusion length and their distribution in the bulk of the base. To study the effect of the temperature on electronic parameters, we take into account, the dependence of carriers (electrons and holes) mobility with the temperature (μn,(T) μp(T)). Then, the resolution of the continuity equation,which is a function of the carriers gradient electric field and the carriers mobility, leads to the expressions of the diffusion coefficient, the diffusion length, and the density of carriers which are function of the temperature. Then, we studied the effects of the temperature on the diffusion parameters in order to explain their effect on the behavior the carriers distribution in intermediate, short circuit and open circuit operating modes at several positions in the base depth. It appears through this study that the diffusion coefficient and the diffusion length decrease with the increase of the temperature. We observe also that with the increase of the temperature, the density of carriers in the base of the solar cell in short circuit and open voltage operating modes increases. In intermediate operating mode, the density of carriers increases also with the temperature but it is function of the base depth.

Solar Photovoltaic is a very promising solution that can greatly contribute in solving the increasing global energy demand. In both rural and urban areas, photovoltaic modules are in some instances installed close to telecommunication antennas or voltage transformers which generate important magnetic fields in their vicinity. The question is whether or not these magnetic fields affect the performances of the photovoltaic installations. This article presents a modelling study of external magnetic field effect on the electrical parameters of a photovoltaic module. The photocurrent, the photovoltage, the electric power, the series and the shunt resistances of the photovoltaic module, made up of ideal cells, are deduced from those of a silicon solar cell. Then, the I-V and P-V curves are plotted and the theoretical values of the electrical parameters of the photovoltaic module are deduced. The series and shunt resistances of the photovoltaic module are calculated using well known equations and the previous electrical parameters. The results show the negative effect of magnetic field on the performance of a solar photovoltaic module.

The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V characteristics. After the resolution of the magneto transport equation and continuity equation of excess minority carriers in the base of the bifacial silicon solar cell under multispectral illumination, the photo-current density and the photovoltage are determined and the J-V and P-V curves are plotted. Using simultaneously the J-V and P-V curves, we determine, according to magnetic field intensity, the peak photocurrent density, the peak photovoltage, the peak electric power, the fill factor and the load resistance at the peak power point. The numerical data show that the solar cell’s peak power decreases with magnetic field intensity while the fill factor and the load resistance increase.

Experimental setup of transient decay which occurs between two steady state operating points is recalled. The continuity equation is resolved using both the junction dynamic velocity (Sf) and back side recombination velocity (Sb). The transient excess minority carriers density appears as the sum of infinite terms. Influence of magnetic field on the transient excess minority carriers density and transient photo voltage is studied and it is demonstrated that the use of this technique is valid only when the magnetic field is lower than 0.001 T.

This work, based on the junction recombination velocity (Sfu) concept, is used to study the solar cell’s electric power at any real operating point. Using Sfu and the back side recombination velocity (Sbu) in a 3D modelling study, the continuity equation is resolved. We determined the photocurrent density, the photovoltage and the solar cell’s electric power which is a calibrated function of the junction recombination velocity (Sfu). Plots of solar cell’s electric power with the junction recombination velocity give the maximum solar cell’s electric power, Pm. Influence of various parameters such as grain size (g), grain boundaries recombination velocity (Sgb), wavelength (λ) and for different illumination modes on the solar cell’s electric power is studied.

One-dimensional study of both electronic and electrical parameters of a silicon solar cell in the presence or not of an electric field, a magnetic field, or an electromagnetic field does not take into account the grain size and the grain boundary recombination velocity. A three-dimensional study, on the contrary, takes those factors into account. However, the three-dimensional study poses the problem of the attenuation of the wave in the grain of the polycrystalline solar cell as well as the issue of finding the expressions of its components. This study aimed to solve these issues by considering radio waves, which are becoming more and more present in our environment via telecommunication masts. We first obtained the expressions of both the electric field and magnetic field in a grain of a polycrystalline silicon solar cell by solving the dispersion equation. Then we investigated the evolution of the radio wave into the grain by analyzing the behavior of the exponential coefficient that appeared in the expressions of both the electric field and the magnetic field. The study has shown that the attenuation of the radio wave can be neglected through the polycrystalline silicon solar grain and by extension through the polycrystalline silicon solar cell.

In this work, a modeling study of the effect of the junction quality on the performance of a silicon solar cell is presented. Based on a one dimensional modeling of the solar cell, the continuity equation of excess minority carriers is solved with boundary conditions taking into account the intrinsic junction recombination velocity and led to analytical expressions of photocurrent density, photovoltage and electric power. The effect of the intrinsic junction recombination velocity or the solar cell junction quality on photocurrent, photovoltage and electric power, is exhibited and we determine the maximum electric power, the junction dynamic velocity at the maximum power point and the conversion efficiency according to the junction quality of the solar cell. From the electric power lost at the junction, we calculated the shunt resistance of the solar cell according to the junction quality.Keywords: Efficiency; Intrinsic junction recombination velocity; Joule effect; Solar cell; Shunt resistance

The Burkina Faso Women in Physics Working Group was formed as a result of the 3rd IUPAP International Conference on Women in Physics in 2008. The effect of the Working Group’s activities on the amount and success of women in physics in Burkina Faso are presented.

This work, presents the intense light effect on electrical parameters of silicon solar such as short circuit current, open circuit voltage, series and shunt resistances, maximum power, conversion efficiency, fill factor. After the resolution of the continuity equation which leads to the solar cell photocurrent and photovoltage expressions, we use the J/V characteristic to determine the solar cell series and shunt resistances. The maximum electric power of the solar cell is determined using the curves of electric power versus junction dynamic velocity, and then, the fill factor and conversion efficiency are calculated. Light concentration and junction dynamic velocity effects on solar cell short circuit current, open circuit voltage, series and shunt resistances, electric power, fill factor and conversion efficiency are also studied. The study proved that with increase of illumination light intensity, the solar cell shunt resistances decreases whereas series resistance, short circuit current, open circuit voltage, electric power, fill factor and conversion efficiency increases. MARTIAL ZOUNGRANA, ISSA ZERBO, MAHAMADI SAVADOGO, SANNA TIEDREBEOGO, BOUBACAR SORO AND DIEUDONNE JOSEPH BATHIEBO

This article presents a one dimensional modeling of the influence of electromagnetic waves on the electric power delivered by a silicon solar cell under monochromatic illumination in steady state. The electromagnetic waves are produced by an amplitude modulation radio antenna of 2MW power of radiation and located at a variable distance of the solar cell [10m,+∞[. The magnetotransport and continuity equations of excess minority carriers are solved with boundary conditions and led to new analytical expressions of minority carrier’s density, photocurrent density, photovoltage and electric power depending on electromagnetic field intensity and wavelength λ. The dependence of the electromagnetic field and the incident light wavelength on photocurrent density, photovoltage and electric power is studied. The intensity of the electromagnetic field depends on the distance between the solar cell and the amplitude modulation radio antenna. We determine the peak power and the operating point of the solar cell according to distance or electromagnetic field intensity and also according to the wavelength of the monochromatic light. KEYWORDS : 1- Amplitude modulation, 2- Radio antenna, 3- Electromagnetic waves, 4- Monochromatic illumination, 5- Solar cell