Single Junction Amorphous Silicon Research Articles

Solar Photovoltaic Parameter Extraction for Three Different Technologies Using Particle Swarm Optimization Method

Industry and academia are becoming more interested in solar energy. The problem of providing an alternative to fossil fuels and limiting the environmental damage brought on by their emissions is what has brought about this increased focus. Solar photovoltaic is the subject of a growing number of studies. The goal of the current investigation is to investigate how various technological modules namely single junction amorphous silicon (a-Si), Hetero junction with Intrinsic Thin-layer (HIT) and multi crystalline silicon (mc-Si) are affected by seasonal spectrum variation respond to Indian climatic circumstances. Compared to many other nations, the entire Indian subcontinent has a relatively distinct climate with distinct seasonal patterns. The four seasons that are considered in this study are summer, winter, monsoon, and post monsoon. The impact of each season varies on the spectrum. Such a study will be helpful to measure the parameter connected to the spectrum and assess its impact on the effectiveness of the PV array. In order to conduct accurate performance investigations, the extraction of the right circuit model parameters is essential. The estimation of the solar PV parameter is done by using Particle swarm optimization (PSO) algorithm.

Analysis of the degradation of amorphous silicon‐based modules after 11 years of exposure by means of IEC60891:2021 procedure 3

AbstractThe degradation of two amorphous silicon‐based photovoltaic (PV) modules, namely, of single junction amorphous silicon (a‐Si) and of micromorph tandem (a‐Si/ ‐Si), after 11 years of exposure in the south of Spain is analyzed. Their I‐V curves were measured outdoors to study the changes of the electrical parameters in the course of three different periods: during the initial days of exposure, during the first year, and in the subsequent 10‐year period. The translation of the curves to an identical set of operating conditions, which enables a meaningful comparison, was done by the different correction procedures described in the standard IEC60891:2021, including the procedure 3, which does not require the knowledge of module parameters, whose values are typically not available. The annual power degradation rates over the entire 11‐year period are 1.12% for the a‐Si module, which is 3.02% for the first year, and 0.98% for the a‐Si/ ‐Si, which is 2.29% for the initial year.

P+aSixC1-x: H/i-aSi:H/n+aSi1-xGex:H graded band gap single junction solar cell with composition graded amorphous silicon carbon alloy as window layer

The work explores the conduct of composition graded amorphous silicon carbon alloy (aSixC1-x: H) as window layer on graded band gap amorphous silicon (p+aSixC1-x: H/i-aSi:H/n+aSi1-xGe x:H) solar cells, for the first time. The working principle of the proposed structure is interpreted with the aid of energy band diagram. Experimentally validated parameters were adopted for the simulation of the proposed structure. It is observed that the proposed structure is efficient in delivering conversion efficiency (η) of 15.39% at 300 K on reducing its window layer thickness to 5 nm, which is commensurate to other announced amorphous silicon solar cells. The momentous cutback in thickness of one of the active layer leads to lesser material demand and diminishes the overall manufacturing cost. Further, the effect of variation in temperature on the proposed structure has been evaluated and observed that the performance remain almost unaltered. Furthermore, the proposed solar cell structure is compared with our previous work and state of art of single junction amorphous silicon solar cell structures.

Mechanical Degradation Analysis of an Amorphous Silicon Solar Module

This work examines the degradation of photovoltaic modules. It assesses the structural defects of amorphous silicon solar cells, which result from mechanical stress at nanoscale level. Firstly, it analyses the interface morphology, deformation, and internal delamination of a single junction amorphous silicon solar module. Secondly, it explores the interface deformation of the layers of the defective region of the module with some statistical tools including root mean root (RSM) and arithmetic mean (Rq). It used the aforementioned tools to demonstrate the effect of microstructural defects on the mechanical behaviour of the entire layers of the module. The study established that the defect observed in the module, emanated from long-term degradation of the a-Si solar cells after years of exposure to various light and temperature conditions. It tested the mechanism of mechanical degradation and its effect on the reliability and stability of the defective and non-defective regions of the module with adhesion force characterisation.

Window Layer Thickness Effect on Amorphous Silicon Oxide Solar Cell Performances

The recent research and developments of a-Si:H based solar cells have greatly promoted its position as low cost solar cell. Unfortunately, a-Si:H solar cells suffer appreciable light induced degradation for thickness greater than 200nm. It has been reported that boron doped hydrogenated amorphous silicon oxide (p-a-SiOx:H) films have a low temperature coefficient compared to those based on hydrogenated amorphous silicon (p-a-Si:H) . Moreover, the solar cells with a p-a-SiOx: H generate more electricity than the solar cells with p-a-Si: H window layer due to the wider band gap (Eg) of these films. We present in this paper a computer simulation on the effects of window layer thickness on the performances of single junction amorphous silicon oxide solar cells. We varied the thickness of the window layer from 5 nm to 25 nm and our simulation results showed that cells parameters are significantly affected window layer thickness. However, the film thickness of the p-a-SiOx:H window layer increased from 5 nm to 25 nm, the power conversion efficiency (PCE) of the solar cells respectively decreased in the ranges of 5.733% to 5.271% .the simulation data are in good agreement with the literature

Enabling Unassisted Solar Water Splitting by Single-Junction Amorphous Silicon Photoelectrodes

Amorphous silicon (a-Si) has been extensively used to fabricate solar cells for efficient light-to-electricity conversion due to its outstanding light-harvesting properties and its facile and low-c...

Analysis, optimisation and experimental validation of [formula omitted]aSi:H/i-aSi:H/p+aSiGe:H graded band gap single junction solar cell

In this paper, we present a single junction graded band gap thin film solar cell using heavily phosphorous doped amorphous silicon, intrinsic amorphous silicon and heavily boron doped amorphous silicon germanium. The first part of the work presents a rigorous analysis of J-V characteristics of recommended photovoltaic structure under short circuit (SC), open circuit (OC), dark and AM 1.5G illumination standard. Further, optimisation of thickness of active layers of the suggested n+ aSi:H/i aSi:H/p+aSiGe:H solar cell structure is done using SCAPS1D solar simulator. The active layer thickness of the proposed solar cell is 430 nm only. Low active layer thickness and absence of multiple junctions reduces the material requirement, complexity and cost of the proposed solar cell. Furthermore, fabrication of individual layers and overall summary of their characterisation have been done. Finally, the proposed structure has been fabricated and validated its J-V characteristics. The fabricated solar cell has short circuit current density (Jsc) of 11.67 mA/cm2, open circuit voltage (Voc) of 1.18 V, fill factor (FF) of 0.857 and conversion efficiency (η) of 11.80% which is on par with other announced single junction amorphous silicon solar cells. Here, we are reporting a single junction graded band gap solar cell using combination of aSi:H and aSiGe:H alloys with varying doping levels for the first time, which is better in conversion efficiency while compact and light.

Confirmation of the Degradation of Single Junction Amorphous Silicon Modules (a-Si:H)

This study examines the degradation of single junction amorphous silicon (a-Si:H) photovoltaic (PV) modules. It summarises the main results obtained from over 7 years of field investigation of the degradation mechanisms of a-Si:H modules. The investigation was based on performance parameters such as fill factors, parasitic resistances, and ideality factors. The initial efficiencies for these modules were in accordance with the expected values; however, a significant decrease was observed during the monitoring period.

Performance evaluation of composition graded layer of aSi1-xGex: H in n+aSi:H/i-aSi:H/p+aSi1-xGex:H graded band gap single junction solar cells

The work investigates the role of composition grading of amorphous silicon germanium alloy on single junction graded band gap amorphous silicon solar cells, for the first time. The fabrication and optical characterization of composition graded aSi1-xGex: H alloy by varying the gas flow rate of germane (GeH4) are presented. We propose the composition graded p+aSi1−xGex: H layer to be considered as one of the active layers in amorphous silicon based solar cells. The principle of operation of the solar cell is illustrated with the energy band diagram of proposed n+aSi:H/i-aSi:H/p+aSi1-xGex:H solar cell structure. Further, the behavior of the structure is evaluated through simulation in terms of proposed layer thickness variation and temperature variation. It is observed that the proposed structure is capable of delivering an open circuit voltage (Voc), short circuit current density (Jsc), Fill Factor (FF) and conversion efficiency (η) of 1.1 V, 15.56 mA/cm2, 0.885 and 15.19% respectively, which is at par with any other single junction amorphous silicon solar cells. The cell performance parameters were compared with related state of the art as well as our previous works. The performance parameters of proposed structure show that it is better to use a single composition graded layer instead of using a number of non-graded composition layers in photovoltaic structures, which reduces complexity and cost of fabrication.

Sacrificial layer assisted front textured glass substrate with improved light management in thin film silicon solar cells

The surface morphology of the front transparent conductive oxide (TCO) films plays a vital role in amorphous silicon thin film solar cells due to their high transparency, conductivity and excellent light scattering properties. Low haze value (5.98%) and surface r.m.s roughness (3.07 nm) are the major issues of aluminium doped zinc oxide (AZO) films to be used as the front TCO due to ineffective scattering of light. Wet chemical texturization of glass substrates using aluminium doped zinc oxide (AZO) as the sacrificial layer was developed in this work to counter those issues. 45% haze and 134 nm surface r.m.s roughness were achieved in AZO coated textured glass. The etched glass/AZO samples presented a much stronger light-scattering capability than the flat glass/AZO and they showed equivalent electrical properties with flat glass/AZO. Single junction amorphous silicon solar cells were fabricated on both flat and textured AZO coated glass substrate and an increment of short circuit current of ~ 12.96% was achieved due to scattering of light from the textured substrate into the cell.

Comparative Performance Analysis of Grid-Connected PV Power Systems with Different PV Technologies in the Hot Summer and Cold Winter Zone

The objective of this paper is to establish the performance of 8 kWp grid-connected photovoltaic (PV) power systems based on different PV module technologies in Nanjing, China. Nanjing has a hot summer and a cold winter which are considered based on monthly average solar irradiation and ambient temperature specifically for the deployment of grid-connected PV systems. The study focuses on performance assessment of grid-connected PV systems using typical PV modules made of monocrystalline silicon (m-Si), polycrystalline silicon (p-Si), edge-defined film-fed growth silicon (EFG-Si), cadmium telluride (CdTe) thin film, copper indium selenide (CIS) thin film, heterojunction with intrinsic thin layer (HIT), and hydrogenated amorphous silicon single-junction (a-Si:H single-PV) installed on location. The yearly average energy output, PV module and system efficiency, array yield, final yield, reference yield, performance ratio, monthly average array capture losses, and system losses of seven PV module technologies are all analyzed. The results show that grid-connected PV power system performance depends on geographical location, PV module types, and climate conditions such as solar radiation and ambient temperature. In addition, based on energy output and efficiency, the HIT PV power technology can be considered as the best option and CdTe and p-Si as the least suitable options for this area. The monthly average performance ratio of the CdTe technology was higher than those of other technologies over the monitoring period in Nanjing.

Adhesion Force Degradation in Degraded Single Junction Amorphous Silicon Module By Scanning Probe Microscopy

The adhesion force between two interface layers in amorphous silicon solar (a-Si:H) module plays a crucial role in its carrier transport across the various interfaces. The quality of each interface layer depends on its mechanical properties. In other words, its mechanical property influences the performance of a-Si:H module. In this study, two mechanical properties of a PV module, which include interfacial adhesion and deformation across layers, were studied. The binding force between interfaces is susceptible to defects as a PV module begins to degrade. Therefore, the changes that occur in the adhesion force of a degraded a-Si:H is a proper tool for degradation analysis. Thus, this paper deals with the microstructure, defects, and mechanical properties of a-Si:H module. The aim of the study was to cross-examine which region of the degraded module was more prone to mechanical degradation. The degradation of adhesive strength results to mechanical defects, which can be observed as microstructural defects when mapped with Scanning Probe Microscope (SPM). The dearth of information on the correlation between these microstructural defects, and adhesive degradation is the motivations for this study. SPM was used to measure the adhesion force between interface layers, at a rate of 0.701Hz. In order to achieve uniformity in the results, each scanning was 512 lines for a retraced direction and the mapping was captured in an upward direction. The study shows that adhesion force exhibits a higher decay in the intrinsic layer interface p/i than in other regions. In addition, the sample from the affected region demonstrated a higher decrease in its adhesion force at the sample time has a higher deformation. Mechanical degradation at nanoscale level enhances interfacial delamination, which can potentially result to premature failure. Thus, an in-depth comprehension of adhesive degradation is essential in degradation analysis.

Simulation and analysis on device parameter variations of single junction hydrogenated amorphous silicon solar cell

A novel single junction amorphous silicon solar cell is investigated by numerical simulation tool AFORS-HET to understand the influence of various parameters such as bandgap, different layer thickness, doping concentrations of P and N layers, transparent conducting oxides as textured and plane surfaces with graded structures on efficiency of solar cell. The trade-off between input parameters were examined in terms of short circuit current density (Jsc), open circuit voltage (Voc), Fill Factor (FF) and efficiency (η) as a function of different structural variations for efficiency enhancement. The systematic approach from front to back layer is investigated and the output parameters are tabulated with varied layer configurations to get clear understanding on the relative improvements over the input parameter variations. Simulated results show that maximum of 8.04% and 11.03% efficiency is seen by graded and textured structures respectively compared to maximum 3.46% efficiency of standard p-i-n structure. A structure with combination of graded and textured layers could provide maximum efficiency up to 19.08% is presented.

Fabrication of Textured Rough SnO2:F Films on Glass Using TiO2 Film as a Buffer Layer

This study proposes an alternative method for preparing SnO2:F films with a pyramid-like surface morphology that are suitable for the transparent electrodes used in amorphous silicon thin-film solar cells. By introducing a TiO2 film as a buffer layer, the crystallographic orientation of the SnO2:F films was changed from random to a (200) plane, and the surface topography of the SnO2:F film transformed from rod-like to pyramid-like; hence, textured, rough SnO2:F films were obtained. An appropriately textured rough surface improves light-trapping and enhances the photocurrent in amorphous silicon thin-film solar cells. The textured SnO2:F films were used as the front electrode in a 1-cm2 single-junction amorphous silicon solar cell yielding an initial efficiency of 9.3%. Light-trapping in the textured SnO2:F films led to a photo-generated current higher than that generated in smooth films.

Effect of oxide based graded buffer and bottom n-layer on the performance of the single junction amorphous silicon solar cells

We have developed oxide based window layer, graded buffer layer and n-layer by radio frequency plasma enhanced chemical vapour deposition (rf-PECVD) method for use in the fabrication of single junction amorphous silicon (a-Si) small area (1 cm2) solar cell. From our earlier study we had observed that higher stabilized efficiency can be obtained using oxide based window and buffer layer. In this study, we have replaced conventional buffer layer by graded buffer (graded with four different band gaps) and conventional n-a-Si:H by wide band gap n-a-SiO:H to improve p/i interface and current density further of a single junction solar cell. The use of these two materials in a single junction a-Si structure enhances the open circuit voltage (Voc) and short circuit current of the cell and the conversion efficiency as well. Graded buffer layer can minimize the p/i interface defects to a large extent causing an improvement of Voc. The bandgap of n-a-SiO:H film is much higher and optical absorption is less than that of n-a-Si:H film having the dark conductivity almost same. Due to low absorption and wide optical gap of n-oxide layer allows more fraction of light enter into the absorber layer after reflection from back reflector resulting in increase in short circuit current. 9.53% of initial efficiency is achieved by the use of graded buffer layer and wide band gap n-layer in single junction small area (1 cm2) solar cell.

Structural and Elemental Analysis of Degraded Single Junction Amorphous Silicon Solar Module

Photovoltaic solar modules have different defects and degradation characteristic modes. These degradation modes normally heats up some regions in the PV module. Depending on the degree and size of the localised heat, the localized heat can rise above the temperature limit of the module and cause damage to the structural orientation. The presence of severe defect and degradation correlates with high temperature gradients that usually results in morphological damage especially under outdoor conditions. The present study investigates the effect of defect/degradation on the surface morphology of single junction amorphous silicon modules (a-Si:H) during outdoor deployment. The observed structural damage was analysed using scanning electron microscope (SEM) and energy dispersion X-ray (EDX) to ascertain the elemental composition. Results show huge discrepancies in the chemical composition constitute alone different regions. The presence of high concentration of carbon and oxygen was found in the affected region.

Record amorphous silicon single-junction photovoltaic module with 9.1% stabilized conversion efficiency on 1.43 m2

Providing two-thirds of the total stabilized power of thin-film tandem MICROMORPHTM technology, the amorphous junction remains a key element in the quest for higher efficiencies. This paper reports and summarizes a considerable work to achieve a record large-area amorphous silicon single-junction photovoltaic module. New hardware has been developed and known process steps have been accurately tuned and combined with new features of cell design. Effort was focused on the deposition of high-quality and low-defect a-Si:H layers that has promoted an improved device stability and resistance against light induced degradation. Efficient light management has been used, and module design has been revised. The word-record performance reported in this paper for a large-area (1.43 m2) stabilized module conversion efficiency (total area) was measured and certified by Swiss PV Module Test Center to be 9.1%. Copyright © 2016 John Wiley & Sons, Ltd.

Behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic modules under outdoor long term exposure.

Four years׳ behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic (PV) modules installed in a relatively dry and sunny inland site with a Continental-Mediterranean climate (in the city of Jaén, Spain) are presented in this article. The shared data contributes to clarify how the Light Induced Degradation (LID) impacts the output power generated by the PV array, especially in the first days of exposure under outdoor conditions. Furthermore, a valuable methodology is provided in this data article permitting the assessment of the degradation rate and the stabilization period of the PV modules.Further discussions and interpretations concerning the data shared in this article can be found in the research paper “Characterization of degradation and evaluation of model parameters of amorphous silicon photovoltaic modules under outdoor long term exposure” (Kichou et al., 2016) [1].

Use of hexamethyldisiloxane for p-type microcrystalline silicon oxycarbide layers

The use of hexamethyldisiloxane (HMDSO) as an oxygen source for the growth of p-type silicon-based layers deposited by Plasma Enhanced Chemical Vapor Deposition is evaluated. The use of this source led to the incorporation of almost equivalent amounts of oxygen and carbon, resulting in microcrystalline silicon oxycarbide thin films. The layers were examined with characterisation techniques including Spectroscopic Ellipsometry, Dark Conductivity, Fourier Transform Infrared Spectroscopy, Secondary Ion Mass Spectrometry and Transmission Electron Microscopy to check material composition and structure. Materials studies show that the refractive indices of the layers can be tuned over the range from 2.5 to 3.85 (measured at 600 nm) and in-plane dark conductivities over the range from 10-8 S/cm to 1 S/cm, suggesting that these doped layers are suitable for solar cell applications. The p-type layers were tested in single junction amorphous silicon p-i-n type solar cells.

An outdoor investigation of the absorption degradation of single-junction amorphous silicon photovoltaic module due to localized heat/hot spot formation

This paper investigates the absorbance degradation of single-junction amorphous silicon (a-Si:H) photovoltaic (PV) module, due to the presence of localized heat. The decrease in optical density is a huge challenge due to the long-term degradation of PV modules. The reduction in solar cell optical density causes a decline in its conversion efficiency. This decreases the photogenerating current, hence reduces the effective efficiency of the PV device. An infrared thermography was used for mapping the module temperature profile. Fourier transform infrared spectroscopy (FTIR) was used for the absorption characterization. The rationale behind the outdoor deployment was to deduce a practical effect of hot spot formation on the module’s absorption ability. The results show a direct correlation between localized heat and the absorption degradation.