Chemical treatment of crystalline silicon solar cells as a method of recovering pure silicon from photovoltaic modules Renewable Energy
Photovoltaic technology is used worldwide to provide reliable and cost-effective electricity for industrial, commercial, residential and community applications.The average lifetime of PV modules can be expected to be more than 25 years.The disposal of PV systems will become a problem in view of the continually increasing production of PV modules.These can be recycled for about the same cost as their disposal.
Photovoltaic modules in crystalline silicon solar cells are made from the following elements, in order of ma: gla, aluminium frame, EVA copolymer transparent hermetising layer, photovoltaic cells, installation box, Tedlar protective foil and aembly bolts.From an economic point of view, taking into account the price and supply level, pure silicon, which can be recycled from PV cells, is the most valuable construction material used. ®Recovering pure silicon from damaged or end-of-life PV modules can lead to economic and environmental benefits.Because of the high quality requirement for the recovered silicon, chemical proceing is the most important stage of the recycling proce.The chemical treatment conditions need to be precisely adjusted in order to achieve the required purity level of the recovered silicon.For PV systems based on crystalline silicon, a series of etching procees was carried out as follows: etching of electric connectors, anti-reflective coating and n-p junction.The chemistry of etching solutions was individually adjusted for the different silicon cell types.Efforts were made to formulate a universal composition for the etching solution.The principal task at this point was to optimise the etching temperature, time and alkali concentration in such a way that only as much silicon was removed as neceary.
Engineering, institutions, and the public interest: Evaluating product quality in the Kenyan solar photovoltaics industry Energy Policy
Solar sales in Kenya are among the highest per capita among developing countries.While this commercial succe makes the Kenya market a global leader, product quality problems have been a persistent concern.In this paper, we report performance test results from 2004 to 2005 for five brands of amorphous silicon (a-Si) photovoltaic (PV) modules sold in the Kenya market.Three of the five brands performed well, but two performed well below their advertised levels.These results support previous work indicating that high-quality a-Si PV modules are a good economic value.The presence of the low performing brands, however, confirms a need for market institutions that ensure the quality of all products sold in the market.Prior work from 1999 indicated a similar quality pattern among brands.This confirms the persistent nature of the problem, and the need for vigilant, long-term approaches to quality aurance for solar markets in Kenya and elsewhere.Following the release of our 2004/2005 test results in Kenya, the Kenya Bureau of Standards moved to implement and enforce performance standards for both amorphous and crystalline silicon PV modules.This appears to represent a positive step towards the institutionalization of quality aurance for products in the Kenya solar market.
Electrical performance results from physical stre testing of commercial PV modules to the IEC 61215 test sequence Solar Energy Materials and Solar Cells
This paper presents statistical analysis of the behaviour of the electrical performance of commercial crystalline silicon photovoltaic (PV) modules tested in the Solar Test Installation of the European Commiion\'s Joint Research Centre from 1990 up to 2006 to the IEC Standard 61215 and its direct predeceor CEC Specification 503.A strong correlation between different test results was not observed, indicating that the standard is a set of different, generally independent stre factors.The results confirm the appropriatene of the testing scheme to reveal different module design problems related rather to the production quality control than material weakne in commercial PV modules.
Efficiency model for photovoltaic modules and demonstration of its application to energy yield estimation
A new method has been proposed [W.Durisch, K.H.Lam, J.Close, Behaviour of a copper indium gallium diselenide module under real operating conditions, in: Proceedings of the World Renewable Energy Congre VII, Pergamon Pre, Oxford, Elsevier, Amsterdam, 2002, ISBN 0-08-044079-7] for the calculation of the annual yield of photovoltaic (PV) modules at selected sites, using site-specific meteorological data.These yields are indispensable for calculating the expected cost of electricity generation for different modules, thus allowing the type of module to be selected with the highest yield-to-cost ratio for a specific installation site.The efficiency model developed and used for calculating the yields takes three independent variables into account: cell temperature, solar irradiance and relative air ma.Open parameters of the model for a selected module are obtained from current/voltage (I/V) characteristics, measured outdoors at Paul Scherrer Institute\'s test facility under real operating conditions.From the model, cell and module efficiencies can be calculated under all relevant operating conditions.Yield calculations were performed for five commercial modules (BP Solar BP 585 F, Kyocera LA361K54S, Uni-Solar UPM-US-30, Siemens CIS ST40 and Wuerth WS11003) for a sunny site in Jordan (Al Qawairah) for which reliable measured meteorological data are available.These represent mono-crystalline, poly-crystalline and amorphous silicon as well as with copper–indium-diselenide, CuInSe2 PV modules.The annual yield for these modules will be presented and discued.
Experimental validation of crystalline silicon solar cells recycling by thermal and chemical methods
In recent years, photovoltaic power generation systems have been gaining unprecedented attention as an environmentally beneficial method for solving the energy problem.From the economic point of view pure silicon, which can be recovered from spent cells, is the most important material owing to its cost and limited supply.
The article presents a chemical method for recycling spent or damaged modules and cells, and the results of its experimental validation.
The recycling of PV cells consists of two main steps: the separation of cells and their refinement.Cells are first separated thermally or chemically; the separated cells are then refined.During this proce the antireflection, metal coating and p–n junction layers are removed in order to recover the silicon base, ready for its next use.This refinement step was performed using an optimised chemical method.Silicon wafers were examined with an environmental scanning electron microscope (ESEM) coupled to an EDX spectrometer.
The silicon wafers were used for producing new silicon solar cells, which were then examined and characterized with internal spectral response and current–voltage characteristics.The new cells, despite the fact that they have no SiNx antireflective coating, have a very good efficiency of 13–15%.
The impact of silicon feedstock on the PV module cost
The impact of the use of new (solar grade) silicon feedstock materials on the manufacturing cost of wafer-based crystalline silicon photovoltaic modules is analyzed considering effects of material cost, efficiency of utilisation, and quality.Calculations based on data provided by European industry partners are presented for a baseline manufacturing technology and for four advanced wafer silicon technologies which may be ready for industrial implementation in the near future.Iso-cost curves show the technology parameter combinations that yield a constant total module cost for varying feedstock cost, silicon utilisation, and cell efficiency.A large variation of feedstock cost for different production procees, from near semiconductor grade Si (30 €/kg) to upgraded metallurgical grade Si (10 €/kg), changes the cost of crystalline silicon modules by 11% for present module technologies or by 7% for advanced technologies, if the cell efficiency can be maintained.However, this cost advantage is completely lost if cell efficiency is reduced, due to quality degradation, by an absolute 1.7% for present module technology or by an absolute 1.3% for advanced technologies.
Thin-film monocrystalline-silicon solar cells made by a seed layer approach on gla-ceramic substrates
Solar modules made from thin-film crystalline-silicon layers of high quality on gla substrates could lower the price of photovoltaic electricity substantially.One way to create crystalline-silicon thin films on non-silicon substrates is to use the so-called “seed layer approach”, in which a thin crystalline-silicon seed layer is first created, followed by epitaxial thickening of this seed layer.
In this paper, we present the first solar cell results obtained on 10-μm-thick monocrystalline-silicon (mono-Si) layers obtained by a seed layer approach on transparent gla-ceramic substrates.The seed layers were made using implant-induced separation and anodic bonding.These layers were then epitaxially thickened by thermal CVD.Simple solar cell structures without integrated light trapping features showed efficiencies of up to 7.5%.Compared to polycrystalline-silicon layers made by aluminum-induced crystallization of amorphous silicon and thermal CVD, the mono-Si layers have a much higher bulk diffusion lifetime.
Waved gla: Towards optimal light distribution on solar cell surfaces for high efficient modules
A method to improve the module efficiency of solar cells by modifying the surface of the gla cover of the solar cells module is proposed.A model is built to show that a better efficiency can be achieved by optimizing the light distribution on the cell, which reduces the shadow loes and thereby allows the finger spacing to be decreased, which in turn decreases the (resistive) ohmic loes.
This method is illustrated by considering industrial crystalline silicon solar cells as an example, however, it applies to all solar cells that are characterized by a metallization pattern on the surface of the solar cell.It is estimated that this method can improve the relative module efficiency by about 5% and halve the front side loes.
Analysis of series resistance of crystalline silicon solar cell with two-layer front metallization based on light-induced plating
Improving the front metallization quality of silicon solar cells should be a key to enhance cell performance.In this work, we investigated a two-layer metallization scheme involving light-induced plating (LIP) and tried to quantify its impact on the series resistance of the front grid metals and FFs on finished cells.To estimate the effect of LIP proceing on a printed and fired seed layer, individual components of series resistance were measured before and after LIP proceing.Among them, grid resistance and contact resistance were closely observed because of their large contribution to series resistance.To optimize the plating on the seed metal grid, the grid resistance of the two-layer metal grid structure was calculated as a function of cro section area of the plated layer.Contact resistivity of the grid before and after LIP proceing was analyzed to understand the contact resistance reduction, as well.As a result, the efficiency of solar cells with 80 μm seed metal grid width increased by 0.3% absolute compared with conventional solar cells of 120 μm metal grid width.The total area of electrodes in conventional cells was 1800 mm and electrodes area of LIP proceed solar cells was 1400 mm.The efficiency gain was due to reduction of shadowing lo from 7.7% to 6.0% without the increase of resistance due to two-layer front metallization.
22Simulation of hetero-junction silicon solar cells with AMPS-1D
Mono- and poly-crystalline silicon solar cell modules currently represent between 80% and 90% of the PV world market.The reasons are the stability, robustne and reliability of this kind of solar cells as compared to those of emerging technologies.Then, in the mid-term, silicon solar cells will continue playing an important role for their maive terrestrial application.One important approach is the development of silicon solar cells proceed at low temperatures (le than 300 °C) by depositing amorphous silicon layers with the purpose of paivating the silicon surface, and avoiding the degradation suffered by silicon when proceed at temperatures above 800 °C.This kind of solar cells is known as HIT cells (hetero-junction with an intrinsic thin amorphous layer) and are already produced commercially (Sanyo Ltd.), reaching efficiencies above 20%.In this work, HIT solar cells are simulated by means of AMPS-1D, which is a program developed at Pennsylvania State University.We shall discu the modifications required by AMPS-1D for simulating this kind of structures since this program explicitly does not take into account interfaces with high interfacial density of states as occurs at amorphous-crystalline silicon hetero-junctions.太阳能硅电池的软件仿真设计与制造
Mapping the performance of PV modules, effects of module type and data averaging 统计实验与数据收集处理：太阳能发电电池背板组件模块的效用与背板材料开发方向选取
Solar Energy A method is presented for estimating the energy yield of photovoltaic (PV) modules at arbitrary locations in a large geographical area.The method applies a mathematical model for the energy performance of PV modules as a function of in-plane irradiance and module temperature and combines this with solar irradiation estimates from satellite data and ambient temperature values from ground station measurements.The method is applied to three different PV technologies: crystalline silicon, CuInSe2 and CdTe based thin-film technology in order to map their performance in fixed installations acro most of Europe and to identify and quantify regional performance factors.It is found that there is a clear technology dependence of the geographical variation in PV performance.It is also shown that using long-term average values of irradiance and temperature leads to a systematic positive bias in the results of up to 3%.It is suggested to use joint probability density functions of temperature and irradiance to overcome this bias.
Outdoor performance evaluation of photovoltaic modules using contour plots 户外太阳能电池背板发电效果/转化率评估评价 Current Applied Physics
The impact of environmental parameters on different types of Si-based photovoltaic (PV) modules (single crystalline Si (sc-Si), amorphous Si (a-Si) and a-Si/ microcrystalline Si (μc-Si)) which have different spectral responses were characterized using contour plots.The contour plots of PV performance as a function of module temperature and spectral irradiance distribution were created to separate the impact of the two environmental parameters.The performance of the sc-Si PV module was dominated by the module temperature while those of a-Si and a-Si/μc-Si ones were mainly influenced by the spectral irradiance distribution.Furthermore, the frequency of outdoor conditions and the reliability of the contour plots of the PV performance were discued for the evaluation of PV modules by means of energy production.最新应用物理学学报
Solar photovoltaic charging of lithium-ion batteries 太阳能——锂电池充电器
Power Sources Solar photovoltaic (PV) charging of batteries was tested by using high efficiency crystalline and amorphous silicon PV modules to recharge lithium-ion battery modules.This testing was performed as a proof of concept for solar PV charging of batteries for electrically powered vehicles.The iron phosphate type lithium-ion batteries were safely charged to their maximum capacity and the thermal hazards aociated with overcharging were avoided by the self-regulating design of the solar charging system.The solar energy to battery charge conversion efficiency reached 14.5%, including a PV system efficiency of nearly 15%, and a battery charging efficiency of approximately 100%.This high system efficiency was achieved by directly charging the battery from the PV system with no intervening electronics, and matching the PV maximum power point voltage to the battery charging voltage at the desired maximum state of charge for the battery.It is envisioned that individual homeowners could charge electric and extended-range electric vehicles from residential, roof-mounted solar arrays, and thus power their daily commuting with clean, renewable solar energy.
Selective ablation with UV lasers of a-Si:H thin film solar cells in direct scribing configuration
材料配比方案与实验选择配置方法
Applied Surface Science 应用表面材料科学学报
Monolithical series connection of silicon thin-film solar cells modules performed by laser scribing plays a very important role in the entire production of these devices.In the current laser proce interconnection the two last steps are developed for a configuration of modules where the gla is eential as transparent substrate.In addition, the change of wavelength in the employed laser sources is sometimes enforced due to the nature of the different materials of the multilayer structure which make up the device.The aim of this work is to characterize the laser patterning involved in the monolithic interconnection proce in a different configuration of proceing than the usually performed with visible laser sources.To carry out this study, we use nanosecond and picosecond laser sources working at 355 nm of wavelength in order to achieve the selective ablation of the material from the film side.To ae this selective removal of material has been used EDX (Energy Dispersive Using X-Ray) analysis, electrical measurements and confocal profiles.In order to evaluate the damage in the silicon layer, Raman spectroscopy has been used for the last laser proce step.Raman spectra gives information about the heat affected zone in the amorphous silicon structure through the crystalline fraction calculation.The use of ultrafast sources, such as picoseconds lasers, coupled with UV wavelength gives the poibility to consider materials and substrates different than currently used, making the proce more efficient and easy to implement in production lines.This approach with UV laser sources working from the film side offers no restriction in the choice of materials which make up the devices and the poibility to opt for opaque substrates.Keywords: laser scribing; selective ablation; a-Si:H.
Use of digital image correlation technique to determine thermomechanical deformations in photovoltaic laminates: Measurements and accuracy 数字化图像匹配技术在太阳能材料评估实验中的应用：决策准确性的提高
Solar Energy Materials and Solar Cells 太阳能材料与电磁学报
An experimental technique to measure the deformation of solar cells in transparent PV modules is presented.This method uses the digital image correlation technique with a stereo camera system.Deformations resulting from thermal loading, where rather small deformations occur compared to tensile or bending experiments, are measured by viewing through the window of a climate chamber.We apply this method to measure the thermomechanical deformation of the gap between two crystalline silicon solar cells by viewing through the transparent back sheet of the laminate.Two PV laminates are prepared, each with three crystalline silicon solar cells that are embedded in transparent polymer sheets on a gla substrate.The first laminate (A) contains non-interconnected cells while the second laminate consists of a standard-interconnected cell string (B).We find the gap between two solar cells to deform 66.3±2 μm between 79.6 and −17.3 °C (laminate A) and 66.4±2 μm (laminate B) between 84.4 and −39.1 °C.We determine an accuracy of 1 μm in displacement for the gap experiment by measuring free expansion of a copper strip and averaging displacement values over regions with homogeneous deformation.Furthermore, the relative error contribution in strain due to the optical influence of the layers on top of the object surface is le than 1×10 for one camera.This is proven by a geometrical consideration.
−6Nanostructure, electrical and optical properties of p-type hydrogenated nanocrystalline silicon films
太阳能发电产氢系统应用中，硅薄膜/贴膜的特性、形态及其性能优化
Vacuum In this paper, p-type hydrogenated nanocrystalline (nc-Si:H) films were prepared on corning 7059 gla by plasma-enhanced chemical vapor deposition (PECVD) system.The films were deposited with radio frequency (RF) (13.56 MHz) power and direct current (DC) biases stimulation conditions.Borane (B2H6) was a doping agent, and the flow ratio η of B2H6 component to silane (SiH4) was varied in the experimental.Films’ surface morphology was investigated with atomic force microscopy (AFM); Raman spectroscopy, X-ray diffraction (XRD) was performed to study the crystalline volume fraction Xc and crystalline size d in films.The electrical and optical properties were gained by Keithly 617 programmable electrometer and ultraviolet-visible (UV-VIS) transmiion spectra, respectively.It was found that: there are on the film surface many faulty grains, which formed spike-like clusters; increasing the flow ratio η, crystalline volume fraction Xc decreased from 40.4 % to 32.0 % and crystalline size d decreased from 4.7 to 2.7nm; the optical band gap Eg increased from 2.16 to 2.4eV.The electrical properties of p-type nc-Si:H films are affected by annealing treatment and the reaction preure.
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中国太阳能电池组件背板背膜TPT市场发展状况及及投资价值分析报告
