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.
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.
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 (μ n, (T) μ p (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 292 Smart Grid and Renewable Energy 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.
Studies on concentrated light influence do not take into account the effect of the heating and this proves to be harmful on photovoltaic parameters. The main purpose of this work is to study the effects of light concentration and the heating caused by this concentration on intrinsic properties and carrier density profile. A thermal model of the PV cell is proposed. By applying the power balance at the steady-state, the PV cell thermal equation is determined. The resolution of this equation leads to temperature profile which shows a rapid increase with light concentration. The mobility n and diffusion n D coefficients of electrons increase to reach their maxima, respectively 2 1 1 max ( ) 1895,31 n cm V s at C=6,77 Suns where temperature is T=430,92 K and 21 max ( ) 76,55 . n D cm s at C= 12,59 Suns where temperature is T=508,24; before decreasing. However, for the holes these parameters decrease slowly with concentration increase. Silicon gap energy decreases while electrons intrinsic density increases with increasing concentration. The variations of these parameters are explained on one hand by their dependence on temperature but also by temperature profile with concentration. An electrical model of the PV cell under variable concentration is also proposed and from which the carrier's density is determined. It emerges that the carrier density increases significantly with concentration ratio. This fact is explained by the photo-generation increase with concentration. And also, by thermal generation increase linked to temperature increases with concentration increase. Results also show that carriers density is greater in the rear side compared to the zone near the junction in opposite to authors who did not take into account temperature effect and who showed that carriers density is greater at the illuminated face.
The Photovoltaic (PV) system is often installed near the telecommunication antenna without takes account the performance degradation that the electromagnetic field can cause. The present work provides the recognition about the greatest losses occur which can cause the overall efficiency drop. In fact, the absorption and the thermodynamic processes are more sensitive to the variation of the electromagnetic field more than FF and thermalization processes in presence of the electromagnetic field. The absorption and thermodynamic mechanism are the main cause of the degradation of the polycrystalline silicon PV cell outputs. The PV cell having height base doping level to get a better resistivity to the electromagnetic field must be chosen to improve theses outputs. Then a low electromagnetic field zones must be searched to install the PV system improving its electrical production performance.
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