Chapter

The Physics of the Solar Cell

Chapter

The Physics of the Solar Cell

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Abstract

IntroductionFundamental Properties of SemiconductorsPN -Junction Diode ElectrostaticsSolar Cell FundamentalsAdditional TopicsSummaryReferences

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... This is typically denoted by the global horizontal irradiance (GHI), which is the PV panel's surface collective solar radiation directly obtained from the sun or indirectly received through diffusion or reflection. So, any factor that causes to lower the GHI will negatively affect the generation of energy from a PV panel [1]. Such factors include year season, the density of air molecules, water vapor, clouds, dust, air pollution, raindrops, snow, and shadow from near objects. ...
... If PR is 5 and VR is 5, then the fault is 22 (1) 6 If PR is 6 and VR is 6, then the fault is 23 (1) Using the Matlab Fuzzy Logic Toolbox, a satisfactory level of performance was reached. The tuning process started from a faulty PV panel only and progressively modifying the fuzzy system to detect all possible faults that might occur in the PV according to the fault types listed in Table 2. ...
... On the other hand, in cases (5-9), the fuzzy logic system illustrated that there were only faulty panels. For example, the case (7) showed that there were three faulty panels (1,3,5). Faulty panels were identified using the tree search algorithm discussed in Algorithm 1. ...
Article
Full-text available
The photovoltaic (PV) panel’s output energy depends on many factors. As they are becoming the leading alternative energy source, it is essential to get the best out of them. Although the main factor for maximizing energy production is proportional to the amount of solar radiation reaching the photovoltaic panel surface, other factors, such as temperature and shading, influence them negatively. Moreover, being installed in a dynamic and frequently harsh environment causes a set of reasons for faults, defects, and irregular operations. Any irregular operation should be recognized and classified into faults that need attention and, therefore, maintenance or as being a regular operation due to changes in some surrounding factors, such as temperature or solar radiation. Besides, in case of faults, it would be helpful to identify the source and the cause of the problem. Hence, this study presented a novel methodology that modeled a PV system in a tree-like hierarchy, which allowed the use of a fuzzy nonlinear autoregressive network with exogenous inputs (NARX) to detect and classify faults in a PV system with customizable granularity. Moreover, the used methodology enabled the identification of the exact source of fault(s) in a fully automated way. The study was done on a string of eight PV panels; however, the paper discussed using the algorithm on a more extensive PV system. The used fuzzy NARX algorithm in this study was able to classify the faults that appeared in up to five out of the eight PV panels and to identify the faulty PV panels with high accuracy. The used hardware could be controlled and monitored through a Wi-Fi connection, which added support for Internet of Things applications.
... The necessary underlying physics of solar cell is based on [7][8][9] that are discussed herein. The free charge carriers, ionized donor like and acceptor like recombination centers and some traps in a solar cell give rise to an electric field (E) and an electrostatic potential (Ψ) as given below: ...
... The built-in potential and barrier width/depletion layer in the hetero-junction are given by [7], ...
... andWD = xn + xp = 2 Vbi (NA + ND) qNAND (8) respectively. The efficiency of the device is [7,8], ...
... The flow of electrons forms a short-circuit current ( ) with a unit of (mA/cm 2 ) as depicted in Fig. 3. On the other hand, connecting a resistive load to the terminals of an illuminated cell develops a voltage (V) across the junction which leads to the generation of forward current ( ) that opposes the photo-generated current ( ℎ ) as illustrated in Fig. 3. The forward diode current can be calculated as [62]: ...
... The energy conversion efficiency ( ) is the ratio of the maximum power density generated from a real cell ( ) to the available solar (light) power density at the solar cell surface ( ). The maximum power density that an ideal solar cell can generate ( ) is the product of and [62]. In real solar cells, the maximum obtainable power ( ) is lower than that of an ideal cell as depicted in Fig. 5. ...
... The ratio of to is called the fill factor (FF). From Fig. 5, FF can be calculated as [62]: ...
... Measurement of the current-voltage curve of solar cell in dark conditions is straightforward method for characterization of photovoltaic device Galiana et al. (2008), Bouzidi et al. (2012). It allows to obtain information about the quality of p-n or p-i-n junction, which is described by ideality factor n, dark current density J 0 and parasitic resistances: series R s and shunt R sh Gray (2005). The diode quality factor n reflects which is the recombination taking dominating the device (recombination at the quasi-neutral regions or in the space charge region). ...
... In general saturation current density J 0 of the junction is a measure of carrier recombination Cuevas (2014) and significantly influences on the solar cell open circuit voltage Gray (2005). The lowest values of dark current density were obtained for GaAs top subcell in both configurations. ...
... Series resistance R s is responsible for non-linear shape of J-V curves, especially in high voltage region. It affects solar cell parameters by increasing the voltage needed for a given current density at high injection levels Gray (2005). R s values estimated for top and bottom subcells are similar, both about 2.7 mΩcm 2 for planar and about 200 mΩcm 2 for vertical configurations. ...
Article
From tandem solar cell we expect a wide absorption range due to different bandgaps of the subcells, higher open circuit voltage Voc and finally better photo conversion efficiency η than single junction solar cell. The main drawback of it is a current limitation i.e. the short circuit current Jsc of whole structure is equal to smaller Jsc of both subcells. However, even two subcells with very good photovoltaic performance do not guarantee the correct operation of tandem solar cell. The tunnel junction plays a crucial role on tandem devices as it has to provide low loss electrical and optical connection between top and bottom subcells. Within this paper we present two subcells: top GaAs based, bottom InGaAsN based with good photovoltaic performance and InGaAs tunnel diode used for InGaAsN/GaAs tandem solar cell construction. We compare reference devices with monolithic tandem cell and conclude about tunnel junction failure based on both dark and illuminated J-V characteristics of the InGaAsN/GaAs final device. Based on detailed analysis of tandem performance we propose two most likely effects responsible for tunnel junction induced deterioration of tandem solar cell performance.
... In addition, the high-density non-uniform meshes with the smallest size, 0.7 nm, are applied around the NPs for more accurate results. The position-dependent optical absorption in the perovskite layer is calculated from the divergence of the time-dependent Poynting vector( ⇀ ∇. ) according to [43]: ...
... Whenever discussing the absorption spectrum, it means the net absorption of the active layer. By employing net absorption spectra and the assumption that each absorbed photon creates an electron-hole pair, the optical generation rate opt ( ) is calculated according to [43]: ...
... The generation rate is operated as a source term in the electrical model to obtain photovoltaic parameters. The current density-voltage (J-V) characteristics are obtained by solving coupled Poisson equations and continuity equations as follows [43]: ...
Article
Hole transfer layer-free perovskite solar cells (HTL-free PSCs) have been proposed to reduce manufacturing costs and improve stability. However, the weak optical absorption of the perovskite layer in the infrared region and ultrathin PSCs design have received less attention. In this study, ultrathin HTL-free PSC based on silver nanoparticles (NPs) at the perovskite layer/ back electrode interface is proposed to increase the light trapping. The thickness of the perovskite layer is only 150 nm. The NPs radius is designed based on Mie theory to lead the highest scattering. By employing a numerical analysis, the effect of the periodicity of NPs on the performance of the PSCs is studied to obtain improved structure. The improved structure showed an absorption enhancement of 48% compared with the device without NPs within 300 nm–1400 nm wavelength. Light scattering and near field enhancement supplied by the Ag NPs are responsible for the broadband absorption increase. Photovoltaic characterizations of the improved proposed solar cell are obtained with coupled optical-electrical numerical analysis. The results showed 25.09 mA/cm ² and 14.96%, respectively, for short-circuit current density and efficiency that the efficiency improved by 56% compared to PSCs without NPs. It is believed that this investigation can provide approaches for the design and production of simple, efficient, and economical PSCs.
... [290] The inverse process of Auger recombination is called impact ionization, where an highly energetic electron collides with another electron in a crystal and creates an electron-hole pair. [291] In general, the recombination rate can be expressed as [163,291] R Aug = (k Aug ,n · n + k Aug ,p · p)(np − n 2 i ), (3.8) where k Aug ,n and k Aug ,p are the corresponding Auger rate constants, depending on if an electron or a hole is involved as a third particle. ...
... [290] The inverse process of Auger recombination is called impact ionization, where an highly energetic electron collides with another electron in a crystal and creates an electron-hole pair. [291] In general, the recombination rate can be expressed as [163,291] R Aug = (k Aug ,n · n + k Aug ,p · p)(np − n 2 i ), (3.8) where k Aug ,n and k Aug ,p are the corresponding Auger rate constants, depending on if an electron or a hole is involved as a third particle. ...
Thesis
Full-text available
In order to facilitate the human energy needs with renewable energy sources in the future, new concepts and ideas for the electricity generation are needed. Solar cells based on metal halide perovskite semiconductors represent a promising approach to address these demands in both single-junction and tandem configurations with existing silicon technology. Despite intensive research, however, many physical properties and the working principle of perovskite PVs are still not fully understood. In particular, charge carrier recombination losses have so far mostly been studied on pure films not embedded in a complete solar cell. This thesis aimed for the identification and quantification of charge carrier recombination dynamics in fully working devices under conditions corresponding to those under real operation. To study different PV systems, transient electrical methods, more precisely Open-Circuit Voltage Decay (OCVD), Transient Photovoltage (TPV) and Charge Extraction (CE), were applied. Whereas OCVD and TPV provide information about the recombination lifetime, CE allows to access the charge carrier density at a specific illumination intensity. The benefit of combining these different methods is that the obtained quantities can not only be related to the Voc but also to each other, thus enabling to determine also the dominant recombination mechanisms.The aim of this thesis is to contribute to a better understanding of recombination losses in fully working perovskite solar cells and the experimental techniques which are applied to determine these losses.
... Solar PV technology, after several decades of development, from the first generation to the present third generation (refer to Table 1; comparison of the three generation PV technologies), has made great progress. The first-generation solar cell refers to a single pen junction of crystalline silicon, exhibiting a high efficiency of up to 26.7% (Kaneka, Japan) [11]. The second generation are amorphous silicon (a-Si), cadmium telluride and CIGS thin film, showing the best efficiency of 23.35% (First solar, Japan). ...
... A typical CIGS solar cell structure is shown in Fig. 1(b) [22e25]. Production process: first, on the substrate, a layer of metal molybdenum (Mo) is deposited as a back electrode by DC magnetron sputtering, followed by the deposition of a p-type CIGS absorber layer, and then the pen junction is formed by a chemical bath deposited n-type CdS buffer layer [26], Intrinsic ZnO and aluminum-doped zinc oxide Al:ZnO (AZO) deposited by magnetron sputtering are used as the window layer, and finally the Ni/Al/Ni electrode is deposited as the current collecting grid line. Sometimes an antireflective film, MgF 2 is deposited on the window layer to reduce the reflection loss of sunlight. ...
Article
Recent progress in high temperature resistance PI substrate with low CTE for CIGS thin film solar cells, Materials Today Energy, https://doi. CIGS modules produced by different manufactures: (a) Solar Frontier's CIGS module on glass substrate, (b) Miasole's CIGS module on stainless steel substrate, (c) Global Solar's CIGS module on stainless steel substrate, and (d) Ascent Solar's CIGS module on PI substrate. J o u r n a l P r e-p r o o f 1 Recent progress in high temperature resistance PI substrate with low Abstract 18 Copper indium gallium di-selenide [Cu(InGa)Se 2 or CIGS] thin film solar cell has 19 attracted great attention due to their high efficiency, low cost potential, less raw 20 materials consumption and so on. Using polyimide (PI) as the flexible substrate, the 21 CIGS thin film solar cell has the advantages of light weight, flexibility and low 22 energy consumption compared with the conventional hard glass substrate. However, 23 there are still challenges in PI foils for flexible CIGS substrate application: (1) the 24 thermal resistance of the PI foils is not high enough, which cannot stand in the high 25 temperature CIGS absorber formation process. (2) The coefficient of thermal 26 expansion (CTE) of the PI foils is too large, which causes peeling-off problems of 27 subsequently deposited Mo back electrode on the PI foils. This paper reviews the 28 J o u r n a l P r e-p r o o f 2 current status of the CIGS solar cells on flexible polyimide. In addition, recent 29 progress and future prospects of the high-temperature resistance and low thermal 30 expansion of PI foils for high efficiency are reviewed. 31
... A PV cell is a semiconductor device that converts sunlight into electricity [53]. However, light, i.e., the incoming photons to be absorbed, must have more incredible energy than the bandgap energy of the cell [54]. The absorbed photon generates pairs of mobile charge carriers (electron and hole), which are then separated by the structure of the device (p-n junction). ...
... Currently, semiconductor materials (usually silicon) in the p-n junction (diode) are commercially used to produce solar cells. The well-known Shockley equation gives the I-U characteristic of a p-n junction [54]. The current generated in the PV cell flows through a semiconductor material. ...
Article
Full-text available
There are three standard equivalent circuit models of solar cells in the literature—single-diode, double-diode, and triple-diode models. In this paper, first, a modified version of the single diode model, called the Improved Single Diode Model (ISDM), is presented. This modification is realized by adding resistance in series with the diode to enable better power loss dissipation representation. Second, the mathematical expression for the current–voltage relation of this circuit is derived in terms of Lambert’s W function and solved by using the special trans function theory. Third, a novel hybrid algorithm for solar cell parameters estimation is proposed. The proposed algorithm, called SA-MRFO, is used for the parameter estimation of the standard single diode and improved single diode models. The proposed model’s accuracy and the proposed algorithm’s efficiency are tested on a standard RTC France solar cell and SOLAREX module MSX 60. Furthermore, the experimental verification of the proposed circuit and the proposed solar cell parameter estimation algorithm on a solar laboratory module is also realized. Based on all the results obtained, it is shown that the proposed circuit significantly improves current–voltage solar cell representation in comparison with the standard single diode model and many results in the literature on the double diode and triple diode models. Additionally, it is shown that the proposed algorithm is effective and outperforms many literature algorithms in terms of accuracy and convergence speed.
... The basic SC parameters J SC , V OC , FF, and Eff. as functions of the temperature are presented in Figure 7. According to [23,24], The results in Figure 7 are in good agreement with theoretical predictions. The short-circuit current increases with temperature, while the value of the coefficient dJ SC /dT is higher for the textured structure (sample A) and equals 66. 5 ...
... has a relevant impact on semiconductor properties and the operation of solar cells. The most important equations for solar cell parameters as functions of the temperature are[24]:From the above equations, if temperature increases, V OC , FF and Eff. should decrease. ...
Article
Today, silicon solar cells (amorphous films and wafer-based) are a main source of green energy. These cells and their components are produced by employing various technologies. Unfortunately, during the production process, chemicals that are harmful for the environment and for human life are used. For example, hydrofluoric acid is used to texture the top electrode to improve light harvesting. In this work, and also in recent ones, we report a way to obtain 3D textures on the top electrode by using zinc oxide nanorods. The efficiency of a textured solar cell structure is compared with the one obtained for a planar zinc oxide/silicon structure. The present results show the possibility to produce efficient solar cells on a relatively thin 50 μm thick silicon substrate. Solar cells with structured top electrodes were examined by numerous measuring techniques. Scanning electron microscopy revealed a grain-like morphology of the magnesium-doped zinc oxide film. The size of the grains is closely related to the structure of the nanorods. The external quantum efficiency of the cells was measured. The obtained solar cell shows response in a wide spectral range from ultraviolet to infrared. Current-voltage and current-voltage-temperature measurements were performed to evaluate basic photovoltaic parameters. At room temperature, the cells efficiency equals to 9.1% for textured structures and 5.4% for planar structures, respectively. The work, therefore, describes an environmentally friendly technology for PV architecture with surface textures increasing the efficiency of PV cells.
... For n ≈ 1 the behaviour of the cell is almost ideal and n ≈ 2 indicates increased influence of carrier recombination within the p-n junction of the PV cell. The ideality factor is an indicator of the quality of the semiconductor [30]. According to this, the current passing through the total of the PV cells will be the same, while the voltage of the PV module will be equal to the sum of the voltages of the PV cells. ...
... 30 Reflectance spectra of the samples for each interval of DH 85°C / 85% RH exposure.For the observation of the colour change of the humidity indicator cards, samples of the structure described in section 3.6.1.2 were exposed to DH 85°C / 85% RH conditions. ...
Thesis
The work presented in this thesis comprises research into degradation paths that cause corrosion of different components of solar photovoltaic (PV) cells and quantifies the impact of corrosion on the energy yield of PV modules. PV modules are exposed to different climatic conditions when they are installed in the field. This exposure causes various degradation modes which affect their reliability to produce electricity and their overall durability. Harsh environments can decrease the lifetime of a PV module below 25 years, which is the threshold lifetime suggested for all climates by most PV manufacturers. Crucially, this is also the expected period over which the cost of generated electricity is most often based yet has not been validated given the relative youth of the PV market. Reduction of the PV module lifetime through degradation and failures can significantly affect the financial and technical viability of solar PV as a source of clean electricity and more robust predictions of module lifetime are urgently required. One very significant cause of failure is corrosion. Environmental moisture penetrates the PV laminates and reacts with the different polymers and metallic parts of the construction, accelerated by higher levels of temperature. From hydrolysis of the most commonly used encapsulant (Ethylene Vinyl Acetate, EVA), acetic acid is produced and attacks further the cell electrical contact metallisation, cell interconnection ribbons and back contact of the PV cells. Corrosion affects mainly the series resistance (Rs) of a PV module, causing severe decrease of the PV electrical power output, and is currently understood to be the second highest cause of energy yield loss of systems installed in the last 10 years. The main areas requiring research have been identified as: determination of the temporal evolution of the distribution of moisture content within a PV module subjected to a given environment; full understanding of the chemical reactions taking place and separation of the impact of the different component degradation on the PV performance of a PV module; investigation of the corrosion impact on the performance of PV modules exposed to outdoor conditions, for a non-tropical climate. The paths that the moisture follows within a PV module have been already investigated through theoretical simulations. However, these simulations currently lack rigorous experimental validation, that includes accurate values of moisture concentration accumulated within a PV module. To this end, a method that measures the equilibrium moisture content absorbed by the polymers contained in a PV module is applied, accompanied by a non-destructive method for the quantification of the moisture presence within a PV module. The values that result from the moisture measurements are used for verification of theoretical simulations implemented with COMSOL Multiphysics. Values of moisture concentration at different positions within a PV module are needed for understanding of the corrosion of the different metallic components contained in a PV module. Published studies of the various mechanisms of corrosion of different components of a PV cell exist but stop short of relating this to power output. This is addressed here, in which a method that separates the impact of each mechanism on the degradation of the electrical power output is presented, thus allowing prediction of specific failure modes for a given bill of materials and operating environment. Half encapsulated PV cells (with either front or rear side exposed) are immersed in acetic acid baths or stored in an environment of high level of relative humidity and temperature (damp heat conditions). The results are compared to the findings of fully encapsulated PV modules aged under the same damp heat (DH) conditions. Both electrical and material characterisation are involved for identification of the different mechanisms. Results show that the most severe degradation is caused by accumulation of acetic acid on the front side of the solar cells. Although aluminium reacts severely with moisture, the aluminium back contact corrosion was found to be a negligible failure mode for fully encapsulated PV modules. Additionally, the impact of different back sheets on corrosion is studied, which again seems to be negligible, as the moisture accumulated at the front side of a PV cell is mainly affected by the diffusion coefficient of the encapsulant. Finally, the impact of corrosion on PV modules installed in the field is poorly addressed in current literature, especially for PV modules exposed to non-tropical climates. The simulations available are not based on the physics of the degradation mode, but are empirical relationships whose parameters are extracted by fitting to indoor performance data. This approach makes these methods unreliable for outdoor predictions. Moreover, they are not validated against real outdoor data. The research in this work has achieved a method to partially understand this effect, as it is very difficult to separate the electrical signatures of different failure modes that occur simultaneously. The method involves the estimation of the series resistance evolution of PV modules operating at Loughborough University for 7 years, combined with visual inspection. The results show that seven years is a short period to observe significant corrosion in a temperate climate, but the method applied is adequate for its detection.
... Based on the DLTS data presented before, electron traps κ and λ are, in fact, removed at this temperature, therefore, they are good candidates to be responsible for the loss in J sc . A reduction in J sc is most often a consequence of large Shockley-Read-Hall (SRH) recombination [46]. Analyzing the PL spectra shown in Fig. 6, it is clear that the integral radiative recombination is by far the lowest in the QD-IBSC device annealed at 630°C, which is consistent with an increased SRH recombination. ...
Article
Electrically active defects present in three InAs/GaAs quantum dots (QDs) intermediate band solar cells grown by metalorganic vapor phase epitaxy have been investigated. The devices’ structures are almost identical, differing only in the growth temperature and thickness of the GaAs layers that cover each InAs QD layer. These differences induce significant changes in the solar energy conversion efficiency of the photovoltaic cells, as previously reported. In this work, a systematic investigation was carried out using deep level transient spectroscopy (DLTS) and Laplace DLTS measurements on control samples and solar cell devices, which have clearly shown that electrically active traps play an important role in the device figures of merit, such as open circuit voltage, short circuit current, and shunt resistance. In particular, it was found that the well-known EL2 defect negatively affects both the open circuit voltage and shunt resistance, more in structures containing QDs, as a consequence of the temperature cycle required to deposit them. Other unidentified defects, that are absent in samples in which the QDs were annealed at 700 °C, contribute to a reduction of the short circuit current, as they increase the Shockley-Read-Hall recombination. Photoluminescence results further support the DLTS-based assignments.
... В случая рассмотрения потока электронов только в одном направлении c длиной l и напряженностью E = -ΔU/l можно получить выражение для тока [3]: I = -qneve S (ΔU/l) (2) Согласно теории ФП с р-п-переходом ток определяется выражением: ...
Article
Full-text available
In this work, the experimentally discovered effect of flexophotovoltaics (FFV) in silicon p-n structures under the influence of local mechanical stress on the front surface is theoretically justified for the first time. The regularities of the manifestation of the FFV effect are determined depending on the value of the local pressure force and the photoexcitation intensity. The experimental data were processed statistically by the least squares method and a new empirical formula was obtained for the experimentally determined dependence of the short-circuit photocurrent of a silicon structure on local mechanical stress.
... где φ -высота потенциального барьера р-п-перехода и S -площадь ФП. В случая рассмотрения потока электронов только в одном направлении c длиной l и напряженностью E = -ΔU/l можно получить выражение для тока [3]: ...
Article
Full-text available
In this work, the experimentally discovered effect of flexophotovoltaics (FFV) in silicon p-n structures under the influence of local mechanical stress on the front surface is theoretically justified for the first time. The regularities of the manifestation of the FFV effect are determined depending on the value of the local pressure force and the photoexcitation intensity. The experimental data were processed statistically by the least squares method and a new empirical formula was obtained for the experimentally determined dependence of the short-circuit photocurrent of a silicon structure on local mechanical stress.
... Supplying afterwards the Five-Parameter Model [58] with the Epoa, TC, TM, and PVdatasheet inputs led to the five corresponding outputs of the model which are (i) the Photocurrent (IL), (ii) Diode reverse saturation current (I0), (iii) Series resistance (Rs), (iv) Shunt resistance (Rsh) and (v) Modified diode ideality factor (nNsVth). These outputs constitute the inputs for the well-established Single Diode Model [59,60] for photovoltaic modules from which power estimations are obtained. The above-mentioned methodology was followed to estimate the energy output of the systems under study (Fig. 3d, e and f). ...
Article
Demand for electricity is expected to increase significantly in the coming decades, one reason being the ongoing decarbonization process of the power and the transportation sectors, in an effort to reduce greenhouse gas emissions and thus alleviate climate change. Photovoltaics that harvest solar energy, coupled with energy storage systems are addressing these challenges effectively. In the current study, the simulated energy winnings from typical photovoltaic-battery (PV-BAT) configurations were economically evaluated, under equal technical and site-specific meteorological conditions. Furthermore, their capital, replacement, operation, and maintenance costs were inquired and the average unit cost of electricity per kWh was estimated based on specific energy cost estimation methods and a Monte-Carlo analysis addressing uncertain meteorological risk factors. The cost of electrical energy production in Greece was examined for six scenarios with varying battery technologies and module topologies. Calculated costs ranged from 0.17 to 0.24 €/kWh indicating a significant downward trend in the unit cost of electricity generated by PV-BAT systems. These findings indicate the need for further investigation into how the integration and utilization of such systems can be optimized. The proposed methodology is developed in line with the circular economy action plan which requires increased system efficiency, storage and renewable energy use.
... In the case of considering the electron flow in only one direction with a length l and an intensity E = -ΔU / l, one can obtain an expression for the [3]: I = -qneve S (ΔU/l) (2) According to the theory of the phase transition with a p-n junction, the current is determined by the expression: I = I0 [e (Ue/kT) -1] (3) Taking into account expression (2) and the fact that the dark current I0 is determined by the sum of the diffusion current of electrons and holes through the p-n junction, we obtain: ...
Article
Full-text available
In this work, the first experimentally discovered effect of flexophotovoltaics (FPV) in silicon p-n-structures under the influence of local mechanical stress on the frontal surface is theoretically substantiated.. The regularities of the manifestation of the FPV effect are determined depending on the magnitude of the local pressure force and the intensity of photoexcitation.. Statistical processing of the experimental data by the least squares method was carried out and a new empirical formula was obtained for the experimentally determined dependence of the short circuit photocurrent of a silicon structure on the local mechanical stress.
... The wider the energy gap, the smaller the recombination rate, and consequently the temperature sensitivity. For a detailed discussion on this matter the reader may refer to [35]. ...
Article
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The decrease of solar cell efficiency with temperature is a known problem for photovoltaics (PV). Temperature sensitivity can lead to a considerable amount of energy losses over the lifetime of solar panels. In this perspective Hybrid Thermoelectric-Photovoltaic (HTEPV) systems, which recover solar cell heat losses to produce an additional power output, can be a suitable option. However only hybridization of wide-gap solar cells is convenient in terms of efficiency gains and deserves investigation to evaluate HTEPV devices effectiveness. In this work we report the modeling and the development of customized bismuth telluride thermoelectric generators, optimized to be hybridized with amorphous silicon (aSi), Gallium Indium Phosphide (GaInP) or Perovskites solar cells. The model results showed in all three cases efficiency gains with a maximum of +3.1% for Perovskites (from 16.4% to 19.5%). These enhancements were then experimentally validated for the case of Perovskites solar cells, for which maximum gains were found to occur at typical operating temperatures of conventional PVs. This experimental evaluation demonstrated in an accurate fashion the real potential of thermoelectric hybridization of solar cells.
... The above-simulated sequences were fed at first into the Sandia Cell and Module Temperature Model [37], to compute PV cell (TC) and PV module temperatures (TM), and subsequently into the five-parameter model [38] leading to the five corresponding outputs of the model: (i) the photocurrent (IL), (ii) the diode reverse saturation current (I0), (iii) the series resistance (Rs), (iv) the shunt resistance (Rsh), and (v) the modified diode ideality factor (nNsVth). These outputs comprise the inputs for the widely accepted single-diode model [39,40] for photovoltaic modules from which power estimations are obtained. ...
Article
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Electricity supply in nonelectrified areas can be covered by distributed renewable energy systems. The main disadvantage of these systems is the intermittent and often unpredictable nature of renewable energy sources. Moreover, the temporal distribution of renewable energy may not match that of energy demand. Systems that combine photovoltaic modules with electrical energy storage (EES) can eliminate the above disadvantages. However, the adoption of such solutions is often financially prohibitive. Therefore, all parameters that lead to a functionally reliable and self-sufficient power generation system should be carefully considered during the design phase of such systems. This study proposes a sizing method for off-grid electrification systems consisting of photovoltaics (PV), batteries, and a diesel generator set. The method is based on the optimal number of PV panels and battery energy capacity whilst minimizing the levelized cost of electricity (LCOE) for a period of 25 years. Validations against a synthesized load profile produced grid-independent systems backed by different accumulator technologies, with LCOEs ranging from 0.34 EUR/kWh to 0.46 EUR/kWh. The applied algorithm emphasizes a parameter of useful energy as a key output parameter for which the solar harvest is maximized in parallel with the minimization of the LCOE.
... A solar PV cell is a semiconductor on which research work on its mathematical modeling is being done continuously by many researchers with different techniques. However, the model suggested in [17] is being widely used, in which the PV cell operation is explained with the help of Shockley's simple diode model. The current supplied by the PV module (I) and the photo current (Iph) in amperes are given by the following expression (1): ...
Article
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Industries with co-generation plants face unprecedented problems due to penetration of renewable energy systems such as solar power on their existing distribution networks. These problems are caused by intermittent solar power. To this end, this paper provides a detailed investigation of the effects due to sudden changes in solar power on an existing industrial distribution network connected to co-generation plants. Moreover, the case studies in this work consider simultaneous operation of a large industry having co-generation captive power plant and large scale solar photovoltaic power plant. The real-time field data for the past three years are used to check the performance of solar photovoltaic power plant, load management, power quality and other concerning issues on the distribution network. In addition to the real-time data, the simulations were performed for the solar power output under different solar irradiance conditions. Moreover, these simulations are used to assess photovoltaic integration effects on a distribution system having a co-generation captive power plant. Finally, this paper put forward photovoltaic integration guidelines to industries and policymakers interested to carry out the integration studies in the future. Keywords: Cogeneration captive power plant Design adequacy Microgrids Renewable energy Solar irradiance conditions This is an open access article under the CC BY-SA license.
... For a single junction solar cell, the short circuit current is the sum of the contributions from each of the three regions: the n-type region ( ), the depletion region ( ), and the p-type region ( ), = + + . By substituting the derivation of each term of this equation [38,39], the total current density can be obtained as: ...
Article
The degradation characteristic of GaInP/GaAs/In0.3Ga0.7As inverted metamorphic (IMM) triple junction solar cells irradiated by 1 MeV electron and 10 MeV proton have been studied and compared to that of traditional GaInP/InGaAs/Ge lattice matched (LM) triple junction solar cells. Both IMM and LM solar cells exhibited very good radiation resistance upon 3.16 × 10¹⁰ MeV/g displacement damage dose electron and proton irradiation level. The remaining factor of maximum output power is 0.86 and 0.85 for electron irradiation and 0.73 and 0.75 for proton irradiation in IMM and LM solar cells, respectively. IMM solar cell showed better properties in current matching in end-of-life condition comparing to that of LM solar cells. 1 MeV electron to 10 MeV proton irradiation relative damage coefficients, Rep, for IMM and LM solar cells are determined as 3.11 and 2.78, respectively, by using equivalent displacement damage dose model. The radiation damage coefficient of diffusion length upon 1 MeV electron and 10 MeV proton irradiation for both types of solar cell structures have been calculated.
... The PT beam with optical power P recv,PT is received by the PV and then converted into electricity for battery charging. The charging current I chg is expressed as [33,34] ...
Preprint
High-power and high-capacity simultaneous wireless information and power transfer (SWIPT) becomes more and more important with the development of Internet of Things technologies. Optical SWIPT, also known as simultaneous light information and power transfer (SLIPT), has unique advantages such as abundant spectrum resources and low propagation divergence, compared with RF technologies. However, optical SWIPT faces many challenges in beam steering and receiver positioning/tracking. Resonant beams generated by spatially separated laser resonators (SSLR) have many advantages, including high power, self-aligned mobility, and intrinsic safety. It has been proposed as the carrier of wireless charging and communication. Using resonant beams, mobile electronic devices can be remotely charged and supported with high-rate data transfer. In this paper, we propose a mobile optical SWIPT system based on asymmetric SSLR and present the system optimization procedure. We also determine the boundary of the achievable charging power and communication capacity, and discuss the trade-off between power transfer and information transfer. Numerical results show that the charging power of the optimized asymmetric system is much higher than that of the symmetric system in the previous work, and meanwhile, the channel capacity is kept almost unchanged.
... The increased current at high temperature has also been reasoned on the basis that more than necessary energy is available to excite electrons in semiconductor for PVE to occur. The increased concentration of electrons at high operating temperatures increases carrier current, as voltage in solar cell drops [14]. Typically, any solar module would operate between 20-40°C (293-313 K), depending on the design and intensity of incoming sunlight. ...
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Copper antimony sulphide (CuSbS 2 ) is a suitable material for construction of solar cells as an absorber, since it increases absorption of solar radiation in cells, and hence energy generation. Another material, MoTe 2 , which acts as a hole transport layer (HTL) is also preferred for solar cells design. MoTe 2 HTL provides an addition back surface field that increases the collection of holes at back contact, thus facilitating generation of photonic energy. The presented research involves an in-silico examination of their tandem effect in solar energy generation, using the simulation software SCAPS-1D. Results reveal that in the MoTe 2 HTL solar cells having 2500 nm thickness of CuSbS 2 absorber layer, the maximum power conversion efficiency achieved was 30.4%, at a bandgap of 1.4 eV. The effects of energy bandgap and thickness of CuSbS 2 absorber layer on performance parameters of solar cells containing short-circuit current (J sc ), open-circuit voltage (V oc ), and fill factor (FF) were also studied. Further, effect of operating temperature was also examined to analyse feasibility on outdoor installation of the designed solar cell.
... The latter two models are empirically derived functions of G c , T a , and wind speed. For each timestamp, the software calculates the IV curve of each cell based on the single-diode model [58] ...
... One diode model of solar PV cells and PV modules[105]. built under normal steady working conditions, such as a fault detection standard, can describe the statistical features of the system when it is under normal ...
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One of the green hydrogen projects is Zero Emission Hydrogen Turbine Center (ZEHTC), in which solar panels, PEM electrolyzer, and diaphragm compressor are used to generate power, and produce hydrogen, and store hydrogen at high pressure, respectively. Faults in any components of photovoltaic (PV) systems, PEM electrolyzers, and diaphragm compressors can seriously affect the efficiency, energy yield as well as security, and reliability of the entire system, if not detected and corrected quickly. In this paper, the types and causes of PV systems, PEM electrolyzer, and diaphragm compressors failures are presented, then different methods proposed in the literature for fault detection and diagnosis (FDD) of systems are reviewed and discussed. Special attention is paid to methods that can accurately detect, localize and classify possible faults occurring in PV arrays. The advantages and limits of FDD methods in terms of feasibility, complexity, cost-effectiveness, and generalization capability for large-scale integration are highlighted. Based on the reviewed papers, challenges and recommendations for future research direction are also provided. In this work different model-based approaches are investigated as well as their validation and applications. An overview of different methodologies available in the literature is proposed, which is oriented to help in developing a suitable diagnostic tool for PEM electrolyzer monitoring and fault detection and isolation (FDI). Model-based methods provide fault detection and identification, are easy to implement, and could be conducted during system operation.
... Fig. 7 shows the spectral response curves of different materials, including gallium arsenide (GaAs) [48], polycrystalline silicon (Poly-Si) [49], monocrystalline silicon (Mono-Si) [50], copper indium selenium/cadmium sulfide (CuInSe 2 /CdS) [51], germanium (Ge) [52], and indium gallium arsenide phosphide (InGaAsP) [53]. According to Kirchhoff's law, we can write down the following equations for this circuit model; that is [54,55] ...
... Earth has a constant rotation axis with 23.5° deviation from the line perpendicular earth's orbit around the sun folio [28][29][30][31]. Since this axis exposes various point on earth in different seasons to sun, heat of earth in different points is different in accordance with solar radiation angle. ...
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The effects of real conditions factors on power and efficiency of photovoltaic panels are studied in this study through testing the panel in real environmental tests. To study the mentioned parameters precisely, two panels with different angles are used. The case study is regarding a region of Arak, Iran in summer and winter seasons. The results show that panel efficiency during winter is higher than summer due to temperature decrement. It is discovered that among air pollutants, Al and Fe have the most share in polluting the air that affect the photovoltaic efficiency. Moreover, measuring the accumulated dust on the panels shows more amount in winter in comparison with summer. The important point in studying the effect of tilt angle is that it affects not only the solar azimuth angle, but also the amount of dust and particles accumulation on the panel.
... The photoactive central layer is preferably a direct band gap semiconductor material that is highly sensitive to photon absorption throughout the entire electromagnetic solar spectrum. Moreover, the photoactive layer forms a PN junction with the electron transport layer, similar to a diode where electron-hole pairs ''excitons'' are generated after photon absorption (Gray et al., 2011). Consecutively, the generated charge carriers are dissociated due to the presence of an electric field at the PN junction as to allow electrons and holes to migrate at the negative and positive electrode terminal, respectively ( Figure 3); (Markvart and Castaner, 2003). ...
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Energy is the driving force behind the upcoming industrial revolution, characterized by connected devices and objects that will be perpetually supplied with energy. Moreover, the global massive energy consumption increase requires appropriate measures, such as the development of novel and improved renewable energy technologies for connecting remote areas to the grid. Considering the current prominent market share of unsustainable energy generation sources, inexhaustible and clean solar energy resources offer tremendous opportunities that, if optimally exploited, might considerably help to lessen the ever-growing pressure experienced on the grid nowadays. The R&D drive to develop and produce socio-economically viable solar cell technologies is currently realigning itself to manufacture advanced thin films deposition techniques for Photovoltaic solar cells. Typically, the quest for the wide space needed to deploy PV systems has driven scientists to design multifunctional nanostructured materials for semitransparent solar cells (STSCs) technologies that can fit in available household environmental and architectural spaces. Specifically, Plasma Enhanced Chemical Vapor Deposition (PECVD) technique demonstrated the ability to produce highly transparent coatings with the desired charge carrier mobility. The aim of the present article is to review the latest semi-transparent PV technologies that were impactful during the past decade with special emphasis on PECVD-related technologies. We finally draw some key recommendations for further technological improvements and sustainability.
Chapter
This chapter evaluates the synthesis of polysilicon and the development of photovoltaic panels for the production of electricity from solar energy. The process from quartz to solar grade silicon is analyzed unit by units presenting the mechanism and its kinetics as well as the units themselves. Next, the solar cells are analyzed and their efficiency in capturing solar energy as electrical circuits evaluating the production of electricity from them in a third section of the chapter.
Chapter
Photovoltaic thermal systems (popularly abbreviated as PVT systems) are well-engineered amalgamation of photovoltaic (PV) modules and solar thermal collector (STC). This chapter deliberates the fundamental concept, design, and basis of classification of this newly emerging solar energy capturing device. Performance parameters of different types of PVTs system have been discussed in detail along with worked out examples. Since PV is a major part of this hybrid collector, detailed mathematical formulation of PV-related parameters has also been presented.
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The fast-drying spray deposition (FDSD) technique for perovskite solar cells (PSCs) is developed to enable the stacking of perovskite absorbers with different work functions, which allows the creation of an additional built-in electric field at the interface during the fermi level realignment process upon contact. FDSD is functional under high relative humidity (RH) ambiance and by design, deposits dry film without the need for post-deposition annealing treatment. Based on a spray coating process, FDSD is also highly scalable. Leveraging FDSD’s multilayer deposition capability, this work explores the implementation of graded energy band architectures to achieve PSCs with enhanced carrier extraction and photovoltaic performances. To demonstrate the potential benefit of this approach, two triple cation mixed halide perovskite formulas are chosen. The two formulas, when stacked together in correct order, produce a heterojunction PSC device with an extra built-in electric field, which helps drift charge carriers towards desired electrodes. The architecture with the proper energy band alignment therefore exhibits enhanced carrier extraction efficiency and, despite being subjected to over 60–80% RH during fabrication, reaches the mean power conversion efficiency (PCE) of 7.4%, with the maximum value of 9.5%. The average PCE translates to over 9.9% and 10.3% improvements over the devices based on the two constituent formulas individually. FDSD demonstrates great flexibility i.e., in-humid-air fabrication process and requiring no post annealing treatments, thereby enabling extremely robust and scalable stacked architecture PSCs with low cost and good performance.
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This article presents a method to estimate the parameters of a photovoltaic cell model in its equivalent circuit of a single-diode using artificial neural networks; more specifically, the multilayer perceptron concept is used. The data required to estimate the parameters are based solely on the information available in the manufacturer’s data sheet. The neural network has two hidden layers and the selected training method was Bayesian regularization. The training data were produced synthetically to ensure that a large part of the range of possible parameter values is covered. The network performance is validated with a data set not included in the training set, making the comparison with a recognised method from the literature, and even more, with experimental data obtained from a real photovoltaic panel. The main advantage of this method is that, once the network is trained, the parameters returned by the network will always be unique for each input provided, which is not the case with other artificial intelligence methods such as genetic algorithms or differential evolution. In addition, this method can be directly applied to other similar problems, only by modifying the inputs and outputs of the network.
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This article experimentally demonstrates a novel, microgrid control algorithm based on a two-layer economic model predictive control framework that was previously developed by the authors. This algorithm is applied to an isolated microgrid with a solar photovoltaic system, a battery bank and a gasoline-fuelled generator. The control system performance is experimentally compared to a baseline algorithm over 5 min and 10 h periods, while an experimentally validated model is used to compare performance over a full year. The results indicate that applying the proposed, two-layer economic model predictive control algorithm can reduce operating costs and CO2 emissions by 5%–10% relative to conventional, rule based methods, and by 10%–15% if improved solar and demand forecasts are available. Furthermore, the proposed two-level algorithm can achieve reductions of up to 5% compared with current state-of-the-art methods which only attempt to optimize performance in the energy management system.
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One of the green hydrogen projects is Zero Emission Hydrogen Turbine Center (ZEHTC), in which solar panels, PEM electrolyzer, and diaphragm compressor are used to generate power, produce hydrogen and store hydrogen at high pressure, respectively. Faults in any components of photovoltaic (PV) systems, PEM electrolyzers, and diaphragm compressors can seriously affect the efficiency, energy yield as well as security, and reliability of the entire system, if not detected and corrected quickly. In this paper, the types and causes of PV systems, PEM electrolyzer, and diaphragm compressors failures are presented, then different methods proposed in the literature for fault detection and diagnosis (FDD) of systems are reviewed and discussed. Special attention is paid to methods that can accurately detect, localize and classify possible faults occurring in a PV arrays. The advantages and limits of FDD methods in terms of feasibility, complexity, cost-effectiveness and generalization capability for large-scale integration are highlighted. Based on the reviewed papers, challenges and recommendations for future research direction are also provided. In this work different model-based approaches are investigated as well as their validation and applications. An overview of different methodologies available in the literature is proposed, which is oriented to help in developing suitable diagnostic tool for PEM electrolyzer monitoring and fault detection and isolation (FDI). Model-based methods provide fault detection and identification, are easy to implement, and could be conducted during system operation.
Chapter
Dye sensitized solar cells (DSSCs) are low-cost and environmentally friendly photovoltaic devices, bearing strong photo-conversion efficiency especially under indoor conditions. In this chapter recent advances obtained from vegetable and bioinspired dyes are presented and a comparison with those of synthetic origin are shown. The aim is to clarify the key concepts connected to electronic injection from the dye to titania semiconductor, photoelectrochemical properties and degradation of DSSCs. Developments of natural and bioinspired sensitizers to obtain photoanodes are outlined. Various counter-electrodes and electrolytes are considered. The limits and advantages of the relevant methods for the study of energy levels and time scales involved in charge transfer processes are discussed and supported by UV-Vis., FTIR, Raman, Emission spectra, cyclic voltammetry, Electrochemical impedence spectroscopy, Tafel and current-voltage characteristic curves, roughness factor. Finally all parameters connected to photoelectric conversion efficiency are shown and some assembly techniques of aforemensioned devices are highlighted.
Chapter
Fresh water is one of the basic needs in daily life where the sources are shrinking due to pollution and climate change. Sea water desalination system is one of the potential solutions that can minimize the scarcity of fresh water. Solar energy is one of the promising renewable energies that can be used for water desalination system. The concepts of solar water desalination system, energy conversion from solar irradiation to thermal energy, and different types of solar thermal collectors are the leading technologies. Solar water desalination is also natural, abundant, environment-friendly than the conventional processes. This chapter describes the different types of solar water desalination system, geometrical shapes, modeling of different types of desalination processes, solar thermal processes, thermal collectors, energy conversion, and performance analysis.
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The growing demand for energy in wearable sensors and portable electronics necessitates the development of self‐contained, sustainable, and mobile power sources capable of harvesting environmental energies. Researchers have made significant strides in implementing photovoltaics, thermoelectrics, piezoelectrics, and triboelectrics in 2D materials. This has resulted in significant advancements in wearable energy harvesting systems based on 2D materials. This review discusses the relationship between synthesis procedures, material structures/properties, and device performance in the context of 2D materials‐based wearable energy harvesting technologies. Finally, challenges and future research opportunities are identified and discussed based on current progress. Overview of 2D materials with unique structure, properties and prepared by various techniques in energy harvesting and application for human‐related applications.
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We investigate the impact of the channel statistics on the average harvested energy when directive lightwave power transfer (DLPT) is used for both indoor and outdoor environments. More specifically, for the indoor scenario, the channel randomness is subject to misalignment effects, while for the outdoor one, atmospheric turbulence is further considered. For both scenarios, closed-form expressions are extracted for the average harvested power, validated via Monte Carlo simulations. Interestingly, the final expressions help to assess the energy harvesting capabilities of a DLPT system and provide valuable insights for hardware implementation.
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Organic solar cells (OSCs) are in high demand due to the need to power micro-powered and wireless indoor electronic devices. However, OSCs have significant disadvantages, such as poor environmental stability, lower efficiency, and low photo stability. Consequently, they have not been commercialized. OSCs are highly dependent on the hole transport layer (HTL). Acidity, hygroscopicity, environmental stability, and the hole transport ability of the HTL are strongly correlated with the overall performance of OSCs. Many studies have examined how acidity and hole transport capability of HTL affect OSC performance, but hygroscopicity has never been studied. Therefore, in this study, we examined the effect of HTL hygroscopicity on the stability of OSC. Two different materials with the same acidity level—polystyrene sulfonate (PSS)-doped polyaniline (PANI) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)—were used as an HTL of poly (3-hexylthiophene): [6, 6]-indene-C60 bisadduct active material-based OSC. Thermogravimetric analysis confirmed that PANI:PSS was less hygroscopic than the PEDOT:PSS. Furthermore, the stability study of the OSCs revealed that PANI:PSS based OSC had a longer stability than PEDOT:PSS based OSC.
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Two-dimensional (2D) transition-metal monochalcogenides have been recently predicted to be potential photo(electro)catalysts for water splitting and photoelectrochemical (PEC) reactions. Differently from the most established InSe, GaSe, GeSe, and many other monochalcogenides, bulk GaS has a large band gap of ∼2.5 eV, which increases up to more than 3.0 eV with decreasing its thickness due to quantum confinement effects. Therefore, 2D GaS fills the void between 2D small-band-gap semiconductors and insulators, resulting of interest for the realization of van der Waals type-I heterojunctions in photocatalysis, as well as the development of UV light-emitting diodes, quantum wells, and other optoelectronic devices. Based on theoretical calculations of the electronic structure of GaS as a function of layer number reported in the literature, we experimentally demonstrate, for the first time, the PEC properties of liquid-phase exfoliated GaS nanoflakes. Our results indicate that solution-processed 2D GaS-based PEC-type photodetectors outperform the corresponding solid-state photodetectors. In fact, the 2D morphology of the GaS flakes intrinsically minimizes the distance between the photogenerated charges and the surface area at which the redox reactions occur, limiting electron–hole recombination losses. The latter are instead deleterious for standard solid-state configurations. Consequently, PEC-type 2D GaS photodetectors display a relevant UV-selective photoresponse. In particular, they attain responsivities of 1.8 mA W–1 in 1 M H2SO4 [at 0.8 V vs reversible hydrogen electrode (RHE)], 4.6 mA W–1 in 1 M Na2SO4 (at 0.9 V vs RHE), and 6.8 mA W–1 in 1 M KOH (at 1.1. V vs RHE) under 275 nm illumination wavelength with an intensity of 1.3 mW cm–2. Beyond the photodetector application, 2D GaS-based PEC-type devices may find application in tandem solar PEC cells in combination with other visible-sensitive low-band-gap materials, including transition-metal monochalcogenides recently established for PEC solar energy conversion applications.
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We propose a novel 4J InGaP/InGaAs-GaAsP MQW/InGaAsNSb/Ge solar cell design, which can provide optimum efficiency under the influence of space irradiation. Under 1-sun AM0 spectrum, the device efficiency is obtained to be 40 %. The impact of carrier removal and deep level traps on the device parameters (Jsc, Voc, and η) is mainly emphasized in this paper. Using APSYS from crosslight Inc, the trap related parameters are defined for each trap concentration from 1 × 10¹³ cm⁻³ to 1 × 10¹⁸ cm⁻³. The multiple quantum wells (MQW) inserted in the intrinsic region of the GaAs p-i-n subcell provided a strong electric field for carrier collection. The visualization of carrier removal effect on device electric field became possible using 3D surface and 2D contour plots. Finally, we present EQE of each subcell, peak efficiency value, and maximum power for the proposed device. With the inclusion of 1 × 10⁴ cm/s surface recombination velocity, 1 × 10¹⁶ cm⁻³ trap concentration, 1 × 10¹⁶ cm⁻³ background doping in the MQW intrinsic region, the peak efficiency is obtained to be 46 % at 600 sun concentration.
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It is a basic description of solar pv cell and solar power harvest technology. This paper describes the scenario of this sector,from its very beginning to current developments. The basic scientific explanation,the working principles,description of used materials, basic physical and chemical phenomena regarding this technology are included in this paper.
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We report a first principle investigation on the new type of ternary semiconductor alloys Na6ZnX4 (X = O, S, Se). Structural and elastic properties show that these elements present low formation energy and it's mechanically stable. The obtained electronic energy band gap results show direct electronic transition along the Γ-symmetry direction involving X-s states (X = O, S, Se) in the valence band maximum and mixed contributions from Na-s and Zn-d states. Optical absorption as high as 10⁴ cm⁻¹ is observed in the visible region in the spectrum, with maximum absorbance being as high as 10⁶ cm⁻¹ in the ultraviolet region. Quasi-harmonic approximations are used to investigate the thermodynamic properties, which show the solid characteristics of the alloys even at high temperature range. Our investigation shows Na6ZnSe4 and Na6ZnO4 to be the best materials among the studied compounds for photovoltaic applications and Na6ZnS4 as the best thermoelectric candidate. The electronic band structure and the physical properties reported for the compounds are reveled for the first time.
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Photovoltaic (PV) systems are considered an important pillar in the energy transition because they are usually located near the consumers. In order to provide accurate PV system models, e.g. for microgrid simulation or hybrid-physical forecast models, it is of high importance to know the underlying PV system parameters, such as location, panel orientation and peak power. In most open PV generation databases, these parameters are missing or are inaccurate.In this paper, we present a framework based on particle swarm optimisation and the PVWatts model to estimate PV system parameters using only power feed-in measurements and satellite-based ERA5 climate reanalysis data. Our sensitivity analysis points out the most relevant PV system parameters, which are panel and inverter peak power, panel orientation, system location and a small but not negligible influence of ambient temperature and albedo. The detailed evaluation on one exemplary PV system shows an acceptable accuracy in panel azimuth and tilt for the use in microgrid PV system simulation. The extracted location has less than 25 km of positioning error in the best case, which is more than satisfying with respect to the underlying data resolution of the ERA5 dataset. Similar results are observed for 10 systems in Europe and the USA.
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A set of equations which accurately describes the physics of modern high-efficiency silicon solar cells is formulated and solved numerically. The transport equations of Marshak and van Vliet are recast into a simple. Boltzmann-like form in which the effects associated with the nonuniform band structure and degenerate carrier concentrations are described by two parameters, the effective gap shrinkage and the effective asymmetry factor. The experimental determination of both of these parameters is also discussed. Adler's contention, that some important features of semiconductor device operation can be modeled accurately by using an electically measured effective bandgap shrinkage with an arbitrarily chosen effective asymmetry factor, is also considered. A semiconductor device is described mathematically by Poisson's equation and two current continuity equations. Using the transport equations, these equations were solved numerically in one dimension. The accuracy of the model was tested by comparing the results of computer calculations to exact, analytical results (for certain simple cases) and to experimental results. The model was shown to accurately describe high-efficiency silicon solar cells under a wide range of operating biases and for solar concentrations that varied from 1 to 250. By using the computer model, we were able to explain a physical mechanism which operates to degrade the performance of BSF solar cells operated under high solar concentration. The model was also used to design cells in which the effects of this degradation were minimized. A two-dimensional numerical solar cell model was also developed. An example of the use of this program in analyzing IBC solar cells is presented.
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A theoretical upper limit of efficiency is obtained for a photovoltaic solar cell which uses a semiconductor with a single energy gap. This limit is not based on a particular material or type of device and may be used with any solar or absorption spectrum.
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A theoretical analysis of the flow of added current carriers in homogeneous semiconductors is given. The simplifying assumption is made at the outset that trapping effects may be neglected, and the subsequent treatment is intended particularly for application to germanium. In a general formulation, differential equations and boundary-condition relationships in suitable reduced variables and parameters are derived from fundamental equations which take into account the phenomena of drift, diffusion, and recombination. This formulation is specialized so as to apply to the steady state of constant total current in a single cartesian distance coordinate, and properties of solutions which give the electrostatic field and the concentrations and flow densities of the added carriers are discussed. The ratio of hole to electron concentration at thermal equilibrium occurs as parameter. General solutions are given analytically in closed form for the intrinsic semiconductor, for which the ratio is unity, and for some limiting cases as well. Families of numerically obtained solutions dependent on a parameter proportional to total current are given for n-type germanium for the ratio equal to zero. The solutions are utilized in a consideration of simple boundary-value problems concerning a single plane source in an infinite filament.
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There has been considerable effort of late directed toward the development of high efficiency solar cells for terrestrial use. Significant progress has been made for their use as an alternative to more conventional energy sources. Silicon solar cells in particular, are rapidly approaching theoretical limitations in efficiency. As an aid to the development of more efficient solar cells, a mathematical model would be invaluable. Solar cell geometries could be compared and optimized before actual fabrication. This would eliminate problems caused by the uncertainties associated with device processing. Because analytic models require too many simplifying assumptions, numerical models must be used. Further, a two-dimensional model is needed because most solar cell geometries cannot be handled adequately in one-dimension. A computer program, SCAP2D (Solar Cell Analysis Program in 2 Dimensions), has been developed which is capable of modeling a variety of solar cell structures under various operating conditions. The potential of this program for use as a design and analysis tool has been demonstrated by modeling the conventional, IBC, and EMVJ solar cells.
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A resume is presented regarding the physics and properties of semiconductors, taking into account aspects of crystal structure, the energy bands, the carrier concentration at thermal equilibrium, carrier transport phenomena, basic equations for semiconductor device operation, and phonon spectra and optical, thermal, and high-field properties of semiconductors. The bipolar devices considered include the p-n junction diode, the bipolar transistor, and thyristors. Unipolar devices are discussed, taking into account metal-semiconductor contacts, JFET and MESFET, the MIS diode and CCD, and MOSFET. A description is provided of special microwave devices, giving attention to tunnel devices, IMPATT and related transit-time diodes, and transferred-electron devices. Photonic devices investigated include LED and semiconductor lasers, photodetectors, and solar cells.
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Solar cell theory, materials, fabrication, design, modules, and systems are discussed. The solar source of light energy is described and quantified, along with a review of semiconductor properties and the generation, recombination, and the basic equations of photovoltaic device physics. Particular attention is given to p-n junction diodes, including efficiency limits, losses, and measurements. Si solar cell technology is described for the production of solar-quality crystals and wafers, and design, improvements, and device structures are examined. Consideration is given to alternate semiconductor materials and applications in concentrating systems, storage, and the design and construction of stand-alone systems and systems for residential and centralized power generation.
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A survey of the properties of the homogeneous semiconductor is presented. The general topics addressed include: bonding and structure, phonons, energy bands, photons, defects, transport, generation-recombination, and kinetics.
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The voltage dependence of the photocurrent JL(V) of CdTe/CdS solar cells has been characterized by separating the forward current from the photocurrent at several illumination intensities. JL(V) reduces the fill factor (FF) of typical cells by 10–15 points, the open circuit voltage (VOC) by 20–50 mV, and the efficiency by 2–4 points. Eliminating the effect of JL(V) establishes superposition between light and dark J(V) curves for some cells. Two models for voltage dependent collection give reasonable fits to the data: (1) a single carrier Hecht model developed for drift collection in p-i-n solar cells in which fitting yields a parameter consistent with lifetimes of 10−9 s as measured by others; or (2) the standard depletion region and bulk diffusion length model fits almost as well. The simple Hecht-like drift collection model for photocurrent gives very good agreement to J(V) curves measured under AM1·5 light on CdTe/CdS solar cells with FF from 53% to 70%, CdTe thickness from 1·8 to 7·0 µm, in initial and stressed states. Accelerated thermal and bias stressing increases JL(V) losses as does insufficient Cu. This method provides a new metric for tracking device performance, characterizes transport in the high field depletion region, and quantifies a significant FF loss in CdTe solar cells. Copyright © 2007 John Wiley & Sons, Ltd.
Article
Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July, 2005 are reviewed. Copyright © 2006 John Wiley & Sons, Ltd.
Article
In order to find an upper theoretical limit for the efficiency of p‐n junction solar energy converters, a limiting efficiency, called the detailed balance limit of efficiency, has been calculated for an ideal case in which the only recombination mechanism of hole‐electron pairs is radiative as required by the principle of detailed balance. The efficiency is also calculated for the case in which radiative recombination is only a fixed fraction f c of the total recombination, the rest being nonradiative. Efficiencies at the matched loads have been calculated with band gap and f c as parameters, the sun and cell being assumed to be blackbodies with temperatures of 6000°K and 300°K, respectively. The maximum efficiency is found to be 30% for an energy gap of 1.1 ev and f c = 1. Actual junctions do not obey the predicted current‐voltage relationship, and reasons for the difference and its relevance to efficiency are discussed.
Article
A measurement procedure is described which allows the contactless measurement of bulk lifetime and surface recombination. The procedure uses the the free-carrier absorption of a long-wavelength laser beam by a modulated free-carrier wave to measure and separate the bulk recombination from the surface recombination. The dependence of the absorption on the modulation frequency is used to accomplish the separation. Limitations of the technique are also discussed.
Article
Theory predicts appreciable bandgap narrowing in silicon for impurity concentrations greater than about 1017 cm−3. This effect influences strongly the electrical behaviour of silicon devices, particularly the minority carrier charge storage and the minority carrier current flow in heavily doped regions. The few experimental data known are from optical absorption measurements on uniformly doped silicon samples. New experiments in order to determine the bandgap in silicon are described here. The bipolar transistor itself is used as the vehicle for measuring the bandgap in the base. Results giving the bandgap narrowing (ΔVg0) as a function of the impurity concentration (N) in the base (in the range of 4.1015–2.5 1019 cm−3) are discussed. The experimental values of ΔVg0 as a function of N can be fitted by: where V1, N0 and C are constants.It is also shown how the effective intrinsic carrier concentration (nie) is related with the bandgap narrowing (ΔVg0).
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Conference Paper
ADEPT (a device emulation program and toolbox), a numerical simulation code for modeling solar cells composed of a variety of semiconductor materials in one, two, and three spatial dimensions, is described. Material models for silicon, GaAs, AlGaAs, CuInSe<sub>2</sub>, CdTe, CdS, and thin film Si:H have been implemented. One-dimensional simulations can be run easily in a personal computer environment, and recent advances in sparse matrix solvers make it possible to run 2D simulations on small workstations
Article
A numerical method for analyzing heterostructure semiconductor devices is described. The macroscopic semiconductor equations for materials with position-dependent dielectric constant, bandgap, and densities-of-states are first cast into a form identical to that commonly used to model heavily doped semiconductors. Fermi-Dirac statistics are also included within this simple, Boltzmann-like formulation. Because of the similarity in formulation to that employed for heavily doped semiconductors, well-developed numerical techniques can be directly applied to heterostructure simulation. A simple one-dimensional, finite difference solution is presented. The accuracy of the numerical method is assessed by comparing numerical results with special-case, analytical solutions. Finally, we apply numerical simulation to two heterostructure devices: the heterostructure bipolar transistor (HBT) and the modulation doped field-effect transistor. The influence of a conduction band spike on the current-voltage characteristics of the HBT emitter-base junction is studied, and the variation with gate bias of the two-dimensional electron gas in a field-effect device is also investigated.
Article
We report on the calculation of electrical characteristics of AlGaN/GaN heterojunction field effect transistors (HFETs). The model is based on the self-consistent solution of the Schrodinger and Poisson equations coupled to a quasi-2D model for the current flow. Both single and double heterojunction devices are analyzed for [0001] or [000-1] growth directions. The onset of a parasitic p-channel for particular growth directions and alloy concentrations is also shown
Article
A 1-D computer simulation code, Thin-Film Semiconductor Simulation Program (TFSSP), for the modeling of TF Si:H solar cells is discussed. The code incorporates a variety of physical models, such as a position-dependent bandgap, electron affinity, dielectric constant, density of states, mobility, exponential band tails, and dangling-bond defect states. This flexibility allows different model assumptions to be analyzed and compared. TFSSP and the physical models used are described. An example simulation of a typical TF Si:H solar cell is presented
Article
The incorporation of a detailed model for the photon recycling effect into an exact numerical solar cell simulation code is described. The commonly encountered radiative lifetime multiplication factor is shown to have both a spatial and bias point dependence. Example simulations show that photon recycling can significantly reduce the effective recombination current and thereby have a large effect on the open circuit voltage of a solar cell. Possible ways to capitalize upon this effect are discussed
Modular Series on Solid State Devices, Volume VI: Advanced Semiconductor Fundamentals
  • R Pierret
  • R Pierret
  • Neudeck
Pierret R, in Pierret R, Neudeck G (Eds), Modular Series on Solid State Devices, Volume VI: Advanced Semiconductor Fundamentals, Chap. 6, Addison-Wesley, Reading, MA (1987).
Introduction to Semiconductor Device Modeling, Chap. 2, World Scientific, Sin-gapore
  • Snowden
Snowden C, Introduction to Semiconductor Device Modeling, Chap. 2, World Scientific, Sin-gapore, 14–36 (1986).