Determination of the Base Optimum Thickness of Back Illuminated (n+/p/p+) Bifacial Silicon Solar Cell, by Help of Diffusion Coefficient at Resonance Frequency

The bifacial silicon solar cell subjected to a magnetic field, is illuminated by the back side by a monochromatic light in frequency modulation, with high absorption, At minority carriers diffusion coefficient resonance frequency, a graphical study of the expressions of recombination velocity on the rear side is carried out. The optimum thickness of the base of the bifacial solar cell is deduced for each resonance frequency.

AC Back Surface Recombination Velocity as Applied to Optimize the Base Thickness under Temperature of an (n+-p-p+) Bifacial Silicon Solar Cell, Back Illuminated by a Light with Long Wavelength

The bifacial silicon solar cell, placed at temperature (T) and illuminated from the back side by monochromatic light in frequency modulation (ω), is studied from the frequency dynamic diffusion equation, relative to the density of excess minority carriers in the base. The expressions of the dynamic recombination velocities of the minority carriers on the rear side of the base Sb1(D(ω, T);H) and Sb2(α, D(ω, T);H), are analyzed as a function of the dynamic diffusion coefficient (D(ω, T)), the absorption coefficient (α(λ)) and the thickness of the base (H). Thus their graphic representation makes it possible to go up, to the base optimum thickness (Hopt(ω, T)), for different temperature values and frequency ranges of modulation of monochromatic light, of strong penetration. The base optimum thickness (Hopt(ω, T)) decreases with temperature, regardless of the frequency range and allows the realization of the solar cell with few material (Si).

Lamella Silicon Solar Cell under Both Temperature and Magnetic Field: Width Optimum Determination

This work deals with determining the optimum thickness of the lamella wafer of silicon solar cell. The (p) base region makes up the bulk of the thickness of the wafer. This thickness has always been a factor limiting the performance of the solar cell, as it produces the maximum amount of electrical charges, contributing to the photocurrent. Determining the thickness of the wafer cannot be only mechanical. It takes into account the internal physical mechanisms of generation-diffusion-recombination of excess minority carriers. They are also influenced by external factors such as temperature and magnetic field. Under these conditions, magneto transport equation is required to be applied on excess minority carrier in lamella base silicon solar cell. It yields maximum diffusion coefficient which result on Lorentz law and Umklapp process. Then from photocurrent, back surface recombination velocity expressions are derived, both maximum diffusion coefficient and thickness dependent. The plot of the back surface recombination calibration curves as function of lamella width, leads to its maximum values, trough intercept points. Lamella optimum width is then obtained, both temperature and magnetic field dependent and expressed in relationships to show the required base thickness in the elaboration process.

A.C. Recombination Velocity as Applied to Determine n⁺/p/p⁺Silicon Solar Cell Base Optimum Thickness

This work deals with determining the optimum thickness of the base of an n+/p/p+ silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (λ), with boundary conditions that impose recombination velocities (Sf) and (Sb) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (Sb). By the graphic technique of comparing the two expressions obtained, depending on the thickness (H) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.

Back Surface Recombination Velocity Modeling in White Biased Silicon Solar Cell under Steady State

In this paper, we extend the concept of back surface recombination through a study of a silicon mono facial solar cell in static regime and under polychromatic illumination. Back surface recombination velocities noted Sbe, Sbj and Sbr are determined for which respectively we derived, the power, the fill factor and the conversion efficiency, that become constant whatever the thickness of the solar cell. We have then obtained the expression of the minority carrier’s density in the base from the continuity equation. We then have determined the photocurrent density, the photo voltage, the power, the fill factor and finally the conversion efficiency.

Back Surface Recombination Velocity Dependent of Absorption Coefficient as Applied to Determine Base Optimum Thickness of an n+/p/p+ Silicon Solar Cell

The monochromatic absorption coefficient of silicon, inducing the light penetration depth into the base of the solar cell, is used to determine the optimum thickness necessary for the production of a large photocurrent. The absorption-generation-diffusion and recombination (bulk and surface) phenomena are taken into account in the excess minority carrier continuity equation. The solution of this equation gives the photocurrent according to absorption and electronic parameters. Then from the obtained short circuit photocurrent expression, excess minority carrier back surface recombination velocity is determined, function of the monochromatic absorption coefficient at a given wavelength. This latter plotted versus base thickness yields the optimum thickness of an n+-p-p+ solar cell, for each wavelength, which is in the range close to the energy band gap of the silicon material. This study provides a tool for improvement solar cell manufacture processes, through the mathematical relationship obtained from the thickness limit according to the absorption coefficient that allows base width optimization.

Back Illuminated N/P/P⁺Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n+/p) and the rear face (p/p+) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of the modulated frequency of back illumination. Thus under these operating conditions, a maximum short-circuit photocurrent is obtained and a low-cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.

Diffusion Coefficient at Resonance Frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination

The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (D(ω, B), in the (p) base leads to maximum values (Dmax) at resonance frequencies (ωr). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, ωr and B, are then established, and will be data for industrial development of low-cost solar cells for specific use.

n⁺-p-p⁺Silicon Solar Cell Base Optimum Thickness Determination under Magnetic Field

Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n+-p-p+ under magnetic field. From the magneto transport equation relative to excess minority carriers in the base, with specific boundary conditions, the photocurrent is obtained. From this result the expressions of the carrier’s recombination velocity at the back surface are deducted. These new expressions of recombination velocity are plotted according to the depth of the base, to deduce the optimum thickness, which will allow the production, of a high short-circuit photocurrent. Calibration relationships of optimum thickness versus magnetic field were presented according to study ranges. It is found that, applied magnetic field imposes a weak thickness material for solar cell manufacturing leading to high short-circuit current.

Influence of Both Magnetic Field and Temperature on Silicon Solar Cell Base Optimum Thickness Determination

The minority carrier’s recombination velocity at the junction and at the back surface is used for the modeling and determination of the optimum thickness of the base of a silicon solar cell in the static regime, under magnetic field and temperature influence. This study takes into account the Umklapp process and the Lorentz effect on the minority carriers photogenerated in the base.

Experimental Processus for Acquisition Automatic Features of I-V Properties and Temperature of the Solar Panel by Changing the Operating Point

A development of an acquisition of the characteristic of a solar panel by automatic load variation system is put into play and coupled to an instrumentation chain for taking account of temperature. A programmed digital microprocessor control enables this automation. Design and implementation of a device for automation of variations of the resistive load are powered by solar panel. It is provided by a PIC 16F877A running a computer program that we have developed on the basis of an algorithm according to the operation that we have set. By varying automatically the resistive load, we were able to automatically acquire the characteristic I-V and temperature of the solar panel. With automatic combinations of the 10 resistors, we have obtained 1024 measures of the characteristic curve of the solar cell which has a good accuracy. The change in load and temperature measurement allows us to have the characteristic curves parameterized by temperature.

Ac Recombination Velocity in a Lamella Silicon Solar Cell

The silicon solar cell with series-connected vertical junction is studied with different lamella widths—the expression of the ac recombination velocity of the excess minority carrier at the back surface is established. Spectroscopy technique reveals dominated impact of the lamella widths of the base.

Development of a Solar Controller with MLI Control

This work presents the development of a solar regulator which manages the charge and discharge of a (lead) battery installed in a photovoltaic system in order to extend its lifetime. The regulator is controlled by a microcontroller (PIC16F877A) and protects the battery against overcharging, deep discharge, but also against temperature drifts. The operating principle is based on the control of a DC-DC converter by a rectangular signal MLI generated by the microcontroller. In addition to the protection function of the regulator, there is included a control and monitoring panel consisting of a visualization interface on which the system quantities can be observed. Thus, it will be given to the user to be able to act on the system. This display interface uses as a display an LCD screen and LEDs. Simulation results are presented to illustrate the operation of the proposed solar controller.

AC Back Surface Recombination Velocity in n⁺-p-p⁺Silicon Solar Cell under Monochromatic Light and Temperature

Excess minority carrier’s diffusion equation in the base of monofaciale silicon solar cell under frequency modulation of monochromatic illumination is resolved. Using conditions at the base limits involving recombination velocities Sf and Sb, respectively at the junction (n+/p) and back surface (p+/p), the AC expression of the excess minority carriers’ density δ (T, ω) is determined. The AC density of photocurrent Jph (T, ω) is represented versus recombination velocity at the junction for different values of the temperature. The expression of the AC back surface recombination velocity Sb of minority carriers is deduced depending on the frequency of modulation, temperature, the electronic parameters (D (ω)) and the thickness of the base. Bode and Nyquist diagrams are used to analyze it.

Study at Two Dimensions of Thermal Transfer through a Fibers Panel Subjected to Climatic Constraints in Dynamic Frequency Regulations Established

From resolution of two-dimensional equation of heat in dynamic frequency regime, we have plotted evolution curves of temperature according to depth of material or in lateral direction. They will allow us to evaluate thermal behavior of towed material. Aim of study is to use fibers as a thermal insulating material by proposing a method for determining effective thermal insulation layer in dynamic frequency regime.

Base Thickness Optimization of a (n+-p-p+) Silicon Solar Cell in Static Mode under Irradiation of Charged Particles

In this work, we propose a method to determinate the optimum thickness of a monofacial silicon solar cell under irradiation. The expressions of back surface recombination velocity depending the damage coefficient (kl) and irradiation energy (øp) are established. From their plots, base optimum thickness is deduced from the intercept points of the curves. The short-circuit currents Jsc0 and Jsc1 corresponding to the recombination velocity Sb0 and Sb1 are determinated and a correlation between the irradiation energy, the damage coefficient and optimum thickness of the base is established.

Solar Controller with Automatic Search Technology for the Maximum Power Point with Autonomy Display

In our work, we have been interested in conducting technological research on the use of photovoltaic energy for lighting. In fact, we have produced a stand-alone photovoltaic system with automatic search for the maximum power point, consisting of a photovoltaic module, a solar regulator, a storage battery and a digital control by microcontroller. The solar field is connected to the input of the regulator and the battery to its output. When the battery voltage is lower than the regulation voltage, the controller operates the photovoltaic generator at maximum power Pmpp and transfers this power to the output. In addition to the protection function, this regulator ensures tracking of the maximum power point (MPPT) and allows the photovoltaic generator to deliver its power whatever the variation of climatic conditions (sunshine and temperature). The main role of the solar regulator is the continuous monitoring of the state of charge of the battery to ensure its protection against overcharging and excessive discharging, the coupling and decoupling of the user as well as its maintenance. The principle of operation is based on controlling a DC-DC converter by a rectangular “PWM” signal generated by a PIC16F874 microcontroller which also controls the entire system. The results of simulation after realization were presented to illustrate the operation of the regulator by curves.

Diffusion Coefficient at Double Resonances in Frequency and Temperature, Applied to (n+/p/p+) Silicon Solar Cell Base Thickness Optimization under Long Wavelength Illumination

The diffusion coefficient of the minority charge carriers in the base of a silicon solar cell under temperature and subjected to a magnetic field, passes in reso-nance at temperature (Topt). For this same magnetic field, the diffusion coeffi-cient of the photogenerated carriers by a monochromatic light in frequency modulation enters into resonance, at the frequency (ωc). Under this double resonance in temperature and frequency, the diffusion coefficient is used in the expression of the recombination velocity of the minority charge carriers on the back side of the base of the solar cell (n+/p/p+), to obtain, by a graphical method, the optimum thickness. A modeling of the results obtained shows a material saving (Si), in the development of the solar cell.

Influence of Heat Exchange Coefficients on Both Optimized Thermal Contact (OTCR) and Critical (CTCR) Resistances at the Contact Interface of a Flat Concrete Slab and a Rice Straw Board

The study is carried out in imperfect contact with a concrete slab wall attached to a panel based on rice straw compressed in a dynamic frequency regime. We will propose the characterization of thermal insulation for thermal resistance of contact (x = 0.05 m). The impact of heat exchange coefficients on the front face (x = 0 m) and the rear face (x = 0.1 m) on these resistors is shown.

A 3D Modelling of Solar Cell’s Electric Power under Real Operating Point

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.