Si Photovoltaic Modules Research Articles

Eco-Innovation Method for Sustainable Development of Energy-Producing Products Considering Quality and Life Cycle Assessment (QLCA)

The sustainability of products remains a challenge, mainly due to the lack of consistent approaches for simultaneously taking into account the key criteria of the concept in the process. This research aims to develop an eco-innovative QLCA method to create new product solutions that integrate quality (customer satisfaction) and environmental impact assessment throughout the product life cycle. The QLCA method includes: (i) product prototyping according to quality and environmental criteria; (ii) prospective assessment of the quality of prototypes, taking into account customer requirements; (iii) prospective life cycle assessment of product prototypes using a cradle-to-grave approach in accordance with ISO 14040; and (iv) setting the direction of product development while taking into account the fulfilment of customer expectations and the need to care for the environment throughout the product life cycle. Owing to the lack of previous research in this area, as well as the popularity of photovoltaic (PV) panels in reducing greenhouse gases, an illustration was obtained and test of the method was carried out on the example of silicon photovoltaic panel modules (Crystalline Si PV Module). In accordance with the adopted assumptions, the results of the QLCA method test showed that the modelled PV prototypes will, in most cases, be satisfactory for customers, but they still require improvement actions to reduce carbon dioxide (CO2) emissions throughout their life cycle. These activities should be consistent so as to achieve quality that satisfies customers. The QLCA method can be used by designers, managers, and decision-makers at the early stages of design, but also during the product maturity phase for its sustainable development.

Delay of the potential-induced degradation of n-type crystalline silicon photovoltaic modules by the prior application of reverse bias

We investigated the influence of the pre-application of reverse bias on the potential-induced degradation (PID) of n-type front-emitter (n-FE) crystalline Si (c-Si) photovoltaic modules. Applying a prior positive reverse bias to n-FE cells delays charge-accumulation-type PID (PID-1), decreases in short-circuit current density (J sc) and open-circuit voltage (V oc). The prior positive bias accumulation may accumulate negative charges in the SiN x , which leads to an increase in a duration for the positive charge accumulation by the PID test applying a negative bias. We also found that sufficiently long prior positive bias application results in the delay of PID-2, a fill factor reduction by the incursion of Na ions into the depletion region of the p–n junction of n-FE cells.

Energy-efficient colorful silicon photovoltaic modules driven by transparent-colored radiative cooling

Building-integrated photovoltaics (BIPVs) shows attractive potential in utilizing solar energy and easing the global greenhouse effect. However, the strong absorption of traditional silicon (Si) photovoltaic (PV) modules makes the high surface temperature and keeps the black appearance. For the current BIPVs, improving the power conversion efficiency (PCE) of Si PV modules with aesthetic requirements remains a great challenge. Herein, we design a novel transparent-colored radiative cooling nanocomposite coating that can be applied to the cover glass of Si PV modules. The functional coating consists of the non-metallic nanoparticle (Si@SiO2 core-shell nanoparticle) for the structural coloration of PV modules and poly (methyl methacrylate) (PMMA) as the matrix. The Si@SiO2 core-shell nanoparticle with Mie resonance selectively reflects visible light to generate a structural color. The PMMA exhibits high transmittance above the bandgap of the Si solar cell and good emittance in the mid-infrared region. The simulated results show that the colored PV modules with integrated coatings display a wide range of colors in the CIE−1931 color space and the PCE loss reduction of all the colored PV modules is less than 10%. Meanwhile, the solar transmittance above the Si bandgap T‾solar > 0.9 and the emittance in the atmospheric window ε‾IR > 0.95. The equilibrium temperature of Si PV modules with functional coatings is only 2∼3 K higher than the ideal minimum. This work provides an alternative and convenient method to design the structural colored PV module with radiative cooling for effectively balancing PV module color and PCE, promoting the development of BIPVs.

Development of repairing technique for interconnection of silicon photovoltaic modules using an induction heating system

One of the origins for the degradations of the performance in Si photovoltaic (PV) modules is the corrosions of the front-side metallization, joints of solder and electrodes, solder and interconnection ribbons, thus increasing the series resistance after long-term exposure. This work proposes a reliable method to repair the failures of solder interconnections by utilizing the local induction heating system. The method will perform without removing the PV modules from the outdoor installation locations leading to time-saving and low maintenance costs. It reveals that the heating time on the failures of the solder joint and solder interconnection in the Si PV module plays a vital role in decreasing the series resistance and recovering the PV performance. The optimized heating conditions were a time of 2.0 s, a 10% output power of 3.5 kW, and a frequency of 900 kHz. The proposed method is effective and yields the recovery of the conversion efficiency of the Si solar cell module, as also confirmed by electroluminescence imaging.

Acceleration of potential-induced degradation in crystalline Si photovoltaic modules after a lightning impulse strike

The potential-induced degradation (PID) is one of the significant issues in realizing low-cost electricity from photovoltaic (PV) power generation plants. In this paper, we have investigated PID in crystalline Si (c-Si) PV modules with conventional p-type multicrystalline Si solar cells after the application of lightning impulse strikes. Lightning impulses with a voltage of −40 kV were applied to the module between the shorted electrodes of the c-Si cell and the mimic aluminum frame. It is confirmed that no degradation in the electrical characteristics of the c-Si cell occurs by applying the impulse only. We have found that the PID of c-Si PV modules was accelerated by applying the impulses between a c-Si cell and a metal frame. The acceleration of PID in the module applied with a lightning impulse might be caused by the migration of Na+ ions easily toward the c-Si cell owing to damage to the ethylene-vinyl acetate encapsulant by impulses.

Identification of the Backsheet Type of Silicon Photovoltaic Modules from Encapsulant Fluorescence Images

Feasibility of the identification of backsheet (BS) composition of field-aged Si photovoltaic (PV) modules based on the analysis of characteristic patterns of UV-excited fluorescence (UVF) of ethylene vinyl acetate copolymer encapsulant is shown. The approach includes BS identification by vibrational spectroscopies and the formation of a database of BS-related characteristic UVF patterns. A multivariate principal component analysis of the UVF images of unknown samples combined with the UVF pattern database allows the BS type to be identified only from UVF images. The geometric place of particular samples in the principal component plots is indicative of the general degradation status of PV modules. The proposed method can be applied for high-throughput noncontact characterization of solar PV plants.

Electrochemical mechanisms of leakage‐current in photovoltaic modules

AbstractThis paper analyzes the mechanisms and pathways for leakage current flow observed in Si photovoltaic modules subjected to high temperature and humidity and a large voltage bias with respect to ground. The current inside of the frame is in the form of electron motion, but in the glass and polymer, it is in at least a large part attributable to the movement of ions. When the mode of current flow changes from electronic to ionic conduction, electrochemical reactions will take place at the interface. This can include reactions that produce volatile chemical species like H2, COx, and O2, along with ionic species such as OH− and H3O+. Here, we see evidence of the importance of different charge carriers with different diffusion rates and the influence of electrochemical processes involved. The application of negative voltage to the cell circuit affects the resistivity of glass producing surfaces with poor conductivity but with some increases in the electrochemical potential producing complicated interactions that are important when the voltage is changed. In the polymer, there is the development of a space charge region and a chemical gradient providing two oppositional forces to current flow, which when released create a complicated discharge process. Here, we give a basic understanding of the charge/discharge of PV cells highlighting how the specific mechanisms are important in understanding some of the degradation processes in PV modules. We find that there is evidence of multiple significant charge carrier species with different diffusion time scales. The glass/polymer interface forms a depleted region of higher resistance after prolonged exposure to current. Charge also builds up at the polymer to cell antireflective coating interface and mostly flows to the gridlines to experience electrochemical reactions. These complexities result in non‐linear behavior where the apparent resistivities of the different layers change during charge/discharging processes, making the modeling of the current flow extremely difficult.

Development of a Suppression Technique of Potential-Induced Degradation by a Formation of Glass Layer in Si PV Modules

Shunt-type potential-induced degradation (PID) is one of the degradation phenomena of photovoltaic (PV) modules which degrade PV performance drastically in short time compared to other degradation modes. In this paper, a new suppression technique of the PID was developed by coating a glass layer (GL) on the top or bottom surface of cover glass using a chemical solution known as liquid glass. PID tests were conducted using PV modules prepared with and without GL. A clear suppression effects of the PID were observed by forming GL, and the occurrence of the PID was delayed about 4 times by the formation of GL on the bottom side of cover glass in PV modules.

Potential-induced degradation of n-type front-emitter crystalline silicon photovoltaic modules — Comparison between indoor and outdoor test results

We perform indoor and outdoor potential-induced degradation (PID) tests for n-type front-emitter (n-FE) crystalline Si (c-Si) photovoltaic (PV) modules and compare their results. The indoor/outdoor acceleration factor for the polarization-type PID (PID-p) of n-FE PV modules is found to be ∼1000 at an indoor test temperature of 85 °C. We observe the progression of the PID-p of n-FE PV modules in rainy days, while their performance is recovered in sunny days. This may be because of the formation of a water film on a module surface acting as a conductive film, resulting in a larger electric field near the n-FE cells in rainy days. The recovery of the PV performance of n-FE modules in sunny days can partly explain the large acceleration factor for the indoor PID test against the outdoor test. • We performed indoor and outdoor PID tests for n-FE PV modules. • n-FE PV modules show polarization-type PID (PID-p) both indoors and outdoors. • The acceleration factor for the PID-p is ∼1000 at an indoor test temperature of 85 °C. • We observe the recovery of PID-p for the outdoor modules in sunny days. • The recovery may be one of the reasons for the large acceleration factor.

Lightweight Flexible Polyimide-Derived Laser-Induced Graphenes for High-Performance Thermal Management Applications

Laser pyrolysis of polyimide (PI) is a promising approach for preparing porous graphenes with hierarchical structures. In this study, we used a dual-focusing lens with a collimator to generate a highly concentrated CO2 laser beam with a high focal energy density. The resulting PI-derived graphene (PIDG) obtained under high-intensity laser irradiation possessed a high degree of graphitization, a low sheet resistance (27.4 Ω/sq.), and a large surface area (240.4 m2/g). Through optimization of the high-intensity laser parameters, we obtained a hierarchical PIDG possessing a fiber-like structure. We used this PIDG as a flexible heater and efficient heat sink for Si photovoltaic (PV) and light-emitting diode (LED) modules. The developed heater could reach a temperature of 202.6 °C under an applied voltage of 16 V, with rapid responses and remarkable flexibility. As a result of improved convective and radiative heat dissipation, the PIDG-based heat sink lowered the operating temperatures of the Si PV and LED modules efficiently. Accordingly, the power conversion efficiency of the Si PV and the lifetime of the LED module both increased dramatically.

Recovery of potential-induced degraded p-type multicrystalline Si PV modules by application of a reverse DC bias

Potential-induced degradation (PID) of photovoltaic (PV) modules based on p-type crystalline Si occurs in large-scale PV systems. The development of a low-cost PID recovery technique is important to maximize the power generation capacity of PID-affected facilities. In this paper, we study a simple PID recovery method for multicrystalline silicon solar cells. PID recovery was conducted by application of a reverse DC-bias voltage to the p-n junction of solar cells in PV modules, without temperature control devices. By using this method, the conversion efficiency of solar cells reduced to approximately 20% of their initial value via a PID test was recovered up to 92%. Additionally, nonuniform temperature increases of PV modules by leakage current were observed during the voltage application.

Influence of light irradiation on the charge-accumulation-type potential-induced degradation of n-type front-emitter crystalline Si photovoltaic modules

We investigated the influence of light irradiation on the charge-accumulation-type potential-induced degradation (PID) of n-type front-emitter (n-FE) crystalline silicon (c-Si) photovoltaic (PV) modules. A PID test under one-sun irradiation leads to faster reductions of short-circuit current–density (J sc) and open-circuit voltage (V oc) compared to the case of a PID test in the dark. This indicates that light irradiation accelerates the charge-accumulation-type PID of the n-FE PV modules. The J sc and V oc reductions become slower under irradiation without ultraviolet (UV) light, showing almost the same time dependence as the PID test in the dark. The acceleration of PID by the addition of UV light may be explained by the excitation of electrons at K0 centers in silicon nitride (SiN x ) and their faster drift to the surface by the electric field applied to SiN x .

Country-specific carbon footprint and cumulative energy demand of metallurgical grade silicon production for silicon photovoltaics

The photovoltaic (PV) industry requires high-quality silica sand to produce metallurgical-grade silicon (MG-Si) for silicon PV (Si PV). However, high-quality deposits are scarce, and using lower-quality resources may increase the carbon footprint and cumulative energy demand (CED) of Si PV modules. The environmental impact of quartz mining and silica sand extraction for PV has not been updated in over 15 years. It's not representative of current methods used for low-quality sand and is not country-specific. As a result, PV production's environmental impact might be underestimated. We used life-cycle assessment to evaluate the carbon footprint and CED of quartz mining, silica sand extraction, and MG-Si production for high-quality (> 98% silica), industrial-grade (95% silica), and low-quality (65% silica) quartz deposits, which are necessary to calculate Si PV's energy and carbon payback time. The carbon footprint per metric ton of silica sand extraction increased from 22.7 kg CO2eq for high-quality quartz to 47.9 for industrial-grade and 86.7 for low-quality. China currently uses foreign industrial-grade quartz but plans to use low-quality domestic resources, which could increase the carbon footprint of producing one kg MG-Si from 12.1 to 16.5 kg CO2eq. The CED could increase from 188 to 286 MJ. We also investigated illegal mining's environmental impact. The carbon footprint and CED of MG-Si production decreased by 26 to 60% for illegal mines compared to legal mines. Illegal MG-Si production can be cheaper and have a lower carbon footprint, and therefore, third-party-supply-chain verifications are essential to ensure that PV doesn't contribute to the problem.

Effect of Bypass Diode on Power Generation of Three-Dimensional Curved Si Photovoltaic Module

Three-dimensional (3-D) curved photovoltaic (PV) modules are a potential power source for vehicles with curved surfaces. However, the irradiance on a 3-D curved PV module is nonuniform compared to a conventional flat PV module, which leads to a current mismatch and reduced power generation performance. The conventional PV modules have bypass diodes (BPD) to mitigate power degradation due to partial shadows. To address nonuniformity specific to 3-D curved PV modules, we investigated the BPD configuration. The effectiveness of the BPD configuration was simulated via optical analysis and circuit analysis with meteorological data (at Tokyo and Phoenix). For 3-D curved PV modules with a radius of curvature in the range of 1–3 m, the effectiveness of BPD becomes more pronounced when the curvature radius and diffuse fraction are smaller. In addition, among the BPD configurations examined in this simulation, remarkable power improvement was obtained when 50% of the total number of solar cells in the module was coupled with BPD. The simulation method was validated via an outdoor experiment using a prototype 3-D curved surface module.

Influence of Light Irradiation on Potential-Induced Degradation for Thin-Film Si Photovoltaic Modules

Delamination observed for superstrate-type thin-film Si photovoltaic (PV) modules exposed outdoors was reproduced by indoor acceleration test with high-voltage application. Such delamination was observed for the PV modules left in the air after potential-induced degradation (PID) acceleration test and was a kind of PID. The delamination occurred near the interface between glass and transparent conductive oxide. In this study the origins of the delamination for thin-film Si PV modules were analyzed and the influences of light irradiation and humidity were also investigated. The delamination occurred only at the position with voltage application and high concentration of Na was detected at the delamination region. Delamination was also enhanced by high humidity. It also turned out that light irradiation delays both deterioration of PV performances and also the delamination by high-voltage application. However, PID behaviors are almost the same regardless of including UV component. This is much different from crystalline Si case that UV component is required for the PID delay.

Impact of soiling on Si and CdTe PV modules: Case study in different Brazil climate zones

Abstract Soiling, particulate accumulation on photovoltaic (PV) module surfaces, reduces the available solar resource and the resulting generated device power. This case-study summarizes initial results of 5-year research on the contrasting soiling conditions in the tropical, subtropical, and semi-arid climates in Brazil. A major objective is to present a case study of the effects of soiling on PV module performance in different Brazil climate zones that represent the primary areas for the current and expanding Brazil solar installations. For this, the paper presents methodologies to quantify the soiling ratio (SRatio) and soiling rate (SRate) for two representative commercial technologies, polycrystalline or multicrystalline silicon (mc-Si) and thin-film cadmium telluride (CdTe) modules, through soiling monitoring stations deployed in the selected climate regions. An aim is to add to the growing soiling-research knowledge base through addressing these key factors and their relationships to critical electrical, solar resource, thermal, and local meteorological and environmental parameters. This paper presents, evaluates, and compares soiling rates and losses in Belo Horizonte, Minas Gerais (Equatorial Tropical: 19.92° S, 43.99° W), Porto Alegre, Rio Grande do Sul (Humid-Subtropical: 30.05° S, 51.17° W), and Brotas de Macaubas, Bahia (Semi-Arid: 12.00° S, 42.63° W). The results show that soiling is moderate in all 3-regions, for example with 0.1%/day

Engineering Cells, Membranes and Light Harvesting/Photosystem II Super-Complexes in Bio-Photoelectrochemical Cells

Photosynthetic organisms, membranes and complexes are attractive starting materials for solar energy conversion (SEC). Our overall goal is to develop methods to perform SEC using these materials in simple, inexpensive and a fashion that will be non-polluting and will not compete with the growth of food materials. I will describe here how the remarkable photocatalytic activity of the photosynthetic apparatus can provide overall water splitting with oxygen and hydrogen production in Bio-Photo-Electro-Chemical (BPEC) cells via the simplest and cleanest of processes wither in the absence or presence of added electron transport molecules. With plant thylakoids, electrons are shuttled by FeCN to a transparent FTO electrode, yielding a photocurrent density of 0.5 mA·cm-2. Hydrogen evolution occurs at the cathode at a bias as low as 0.8 V. A tandem cell comprising the BPEC cell with the thylakoid membranes and a Si photovoltaic module achieves overall water splitting with solar to hydrogen conversion efficiency of 0.3% (Pinhassi et al. Nature Communications 2016). With cyanobacterial cells, electrons from the respiratory system are energized by the photosynthetic system and transferred directly to a graphite electrode, utilizing endogenous electron carriers, especially NADPH (Saper et al. Nature Communications 2018 and Shlosberg et al. iScience 2020). The current produced can be used for hydrogen production at low additional bias for significantly longer durations than the plant thylakoids.Another route is to use isolated photosynthetic complexes and chemically connect them to the electrochemical cell. One of the issues with this strategy is the small number of light absorbing chromophores connected to the complex, lowering the photochemical efficiency. Connection of isolated light harvesting (LH) complexes can help to overcome this deficiency. Photosystem II (PSII) is the only enzyme that catalyzes light-induced water oxidation being the basis for its application as a biophotoanode in various bio-photovoltaics and photo-bioelectrochemical cells. However, the absorption spectrum of PSII limits the quantum efficiency in the range of visible light, due to a gap in the green absorption region of chlorophylls (500 - 600 nm). To overcome this limitation, we have used two strategies: stabilizing the interaction between PSII and Phycobilisomes (PBSs) –LH complex or direct connection to modified gold-nanoparticles (Au-NPs) that serve both as LH and electron conduit. Integration of the PBS-PSII super-complexes within an Os-complex-modified hydrogel on macro-porous indium tin oxide electrodes (MP-ITO) resulted in notably improved, wavelength dependent, incident photon-to-electron conversion efficiencies (Hartmann et al. J. Mat. Chem. A. 2020). With the Au-NPs, record currents were obtained, with strong improvement in the SPR range of wavelengths that are not absorbed by chlorophylls.

Impact of Angular Irradiation Profiles on Performance of Silicon PV Modules Using Light Scattering Films

Light trapping strategies, such as light scattering films (LSFs) present an opportunity to increase the power generated by Si photovoltaic modules. Evaluation of the benefits of these strategies for manufacturing decisions currently relies on current-voltage measurements performed using solar simulators under standard test conditions, with uncertainties representing expected variations due to different angles of incidence that result from the light sources of solar simulators. The practical achievement of normal incidence is challenging and consequently the angular irradiation profile varies between different solar simulators. In this article, we show that use of LSFs can enhance the short circuit current density, J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> , of modules by 2.5% under normal incidence as compared to enhancements of 2.33%, 2.12%, and 1.56% measured using three different solar simulators (two short-tunnel and one table). This variation is due to the less effective light trapping of LSFs under more diffuse light. The angular response of these LSF modules on electricity yield is demonstrated through simulations using the angular matrix framework and SunCalculator software. The average J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> enhancement varies from 1.46% (Cologne) to 1.63% (Alice Springs) corresponding to a decrease in diffuse irradiation at Alice Springs. Differences in measured J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> from three solar simulators can result in the predicted average J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> enhancements varying from -0.07% to 0.87% absolute, with the table simulator more closely predicting the average J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SC</sub> enhancement. This highlights the importance of considering the angular profiles of solar simulators if electricity yield and hence returns on investment for PV deployments is to be more accurately predicted.

Influence of light illumination on the potential-induced degradation of n-type interdigitated back-contact crystalline Si photovoltaic modules

We investigate the potential-induced degradation (PID) of n-type interdigitated back-contact (IBC) crystalline Si (c-Si) photovoltaic (PV) modules under a negative bias stress and the influence of light illumination on the PID. IBC PV modules show PID characterized by a reduction in the short-circuit current density (J sc) and open-circuit voltage (V oc) under negative bias stress, while no fill factor (FF) reduction is observed. The degradation may originate from the introduction of sodium (Na) into c-Si and the resulting enhancement of carrier recombination on the surfaces of the IBC cells. Light illumination of 1 sun during the negative bias PID test results in less severe reductions of J sc and V oc. A reduction in the electric field on the surface Si nitride (SiN x ) film, due to carrier generation in the SiN x and the resulting increase in its conductivity, is a possible explanation for the mitigation of the Na-related PID.

Degradation of plated silicon solar module due to copper diffusion: The role of capping layer formation and contact adhesion

Copper plating can provide significant cost savings over screen printed Ag for industrially produced Si photovoltaic modules, however concerns exist with regard to the durability of Cu-plated modules. This study investigated the effect of different capping layers and their method of application on the durability of Cu-plated PERC one-cell modules, with a focus on durability after damp heat (DH) testing. It is shown that the adhesion of Cu-plated fingers capped with immersion-plated Ag and Sn was poorer than that of fingers capped with light-induced plated (LIP) Ag due to the under-etching of Cu finger by corrosive additives that are present in the immersion plating formulations. It is proposed that the weak finger adhesion resulted in fingers dislodging during DH testing of the modules, thereby opening a pathway for Cu to in-diffuse into Si resulting initially in an increased non-ideal recombination and then increased series resistance due to encapsulant flowing under the dislodged finger. Increased recombination due to the Cu in-diffusion was evident in cells with poor finger adhesion through an increase of the non-ideal recombination current density, J02, of 166%, 253%, 266% for LIP Ag, immersion Ag and immersion Sn, respectively, during the first 1000 h of DH. In comparison, with stronger finger adhesion, J02 increases were <60% in the same DH period. This result highlights the importance of strong finger contact adhesion, and not just busbar adhesion, for durable Cu-plated modules and suggests that both finger and busbar adhesion are routinely monitored in the processing of Cu-plated cells.