CdTe Photovoltaic Modules Research Articles

Experimental investigation on the electrical and hydrogen-production performance of a novel PEM electrolyzer driven by CdTe PV with a tracking system

Addressing the challenges of intermittent and variable energy supply, solar hydrogen production via electrolysis has garnered significant attention due to its unique advantages, emerging as a hot topic in the scientific research domain. However, the application of this technology is currently mainly related to the non-tracking system, which undergoes a rapid change in solar irradiation during the day. To expand the matching relationship of solar irradiation, PV characteristics, and electrolyzer, this paper proposes the development of a Proton Exchange Membrane (PEM) electrolyzer driven by Cadmium Telluride (CdTe) photovoltaic (PV) modules with a tracking system for hydrogen production. An experimental platform was set up in Chengdu and the performance tests were carried out for different operating modes during summer. The experimental results demonstrate that the average electrical and hydrogen production efficiencies of the system are 13.11% and 7.88%, respectively, on a sunny day, with a total of 566.7 L of hydrogen produced within 7 h of operation. Furthermore, the solar irradiation received by the tracking surface of the system is significantly enhanced by 10.29% in comparison to the horizontal surface. On a cloudy day with an electrolyzer inlet water temperature of 45 °C, the system has the potential to achieve a hydrogen production efficiency of 11.15 %. At a constant current density of 1.0 A/cm2, the efficiency of the electrolysis process increased by 2.07% and 1.25% for each 10 °C increase in the temperature of the electrolyzer, having an inlet temperature of 35 °C. This study offers a novel approach for a PV-PEM system with a higher hydrogen production efficiency while also establishing a robust foundation for technology optimization and broader implementation.

Picosecond pulsed laser scribing of Cd2SnO4-based CdTe thin-film solar cells on flexible glass

CdTe photovoltaic modules are the most commercially successful thin-film solar cells. In particular, flexible CdTe modules are a promising development in photovoltaic architecture. Cd2SnO4 (CTO) is a low-cost transparent conductive material with excellent optical and electrical properties. Although laser scribing is commonly used to produce cell interconnects in the manufacturing of thin-film PV modules, the laser scribing process window for CTO-based CdTe cells is narrow, and more research is needed on direct laser scribing of flexible CdTe solar cells. In this study, the picosecond pulsed laser scribing of CdTe solar cells with CTO front electrodes and flexible glass substrates was investigated using lasers with the wavelengths of 355 and 532 nm. The flexible cells were suctioned onto a working platform, and a direct ablation method was adopted. The damage and removal thresholds of the CTO, CdTe, and Ni layers were studied and the effects of the spot spacing, multilayer conditions, and laser polarization state were investigated. A method for determining the scribing parameters was proposed. Very smooth scribing grooves were obtained using the optimized laser scribing process. The series and shunt resistances of the cells after laser scribing showed no significant differences compared to those of the control cells.

End of life management of crystalline silicon and cadmium telluride photovoltaic modules utilising life cycle assessment

The rapid global adoption of solar photovoltaic (PV) modules created the issue of recycling and disposal at their end of life. Several PV modules installed in the late 1980s or early 1990s have reached the end of their 30-year useful life and are now being removed as PV trash. This enormous amount of PV trash acknowledges recycling as a crucial and significant area in the value chain of PV industries. Hence, this study uses an end-of-life perspective to discuss the life cycle evaluation of two market-dominant PV technologies— c-Si and CdTe. This method examines recycling and avoided burden due to recovered material independently in order to determine the overall environmental benefit. The study concludes that recycling glass, metals like copper and aluminium, and semiconductor material from both c-Si and CdTe PV modules has a lower environmental effect than mining, providing, and refining the same components from original sources.

The influence of sand on the performance of CdTe photovoltaic modules of different colours and transparencies

The influence of sand on the performance of CdTe photovoltaic modules of different colours and transparencies

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

Spectral gain and loss of different-type photovoltaic modules through average photon energy of various locations in Japan

Spectral gain and loss (spectral gain&loss) of different-type photovoltaic (PV) modules, which are (1) amorphous silicon (a-Si), (2) perovskite (PVK), (3) CdTe, (4) CuInSe2, (5) multi-crystalline silicon, (6) single-crystalline silicon back-contact, and (7) heterostructure-with-intrinsic-thin-layer PV modules, is examined at different locations (Naganuma, Tsukuba, Gifu, Tosu, and Okinoerabu cities in Japan). Reference single-crystalline (sc-Si) PV module is utilized. It is revealed that average photon energy (APE) is uniquely used as an index of solar spectral irradiance regardless of outdoor sites, where APE of 1.59 eV represents airmass 1.5G spectrum with wavelength range from 350 nm to 1700 nm. APE is varied, depending on locations and seasons in a year, and it is the highest of over 1.59 eV (or blue-rich spectra) in summer. Average APE values in four-year period are 1.623 eV, 1.612 eV, 1.618 eV, 1.621 eV, and 1.652 eV at Naganuma, Tsukuba, Gifu, Tosu, and Okinoerabu cities, respectively, representing blue-rich spectra. Ultimately, spectral grain&loss of a-Si, PVK, and CdTe PV modules is above 1 (spectral gain) at investigated locations, implying that appropriate a-Si, PVK, and CdTe PV technologies with large bandgap outperform reference sc-Si PV technology in term of spectral response. Spectral grain&loss with different seasons is additionally discussed.

Utilization of spectral mismatch correction factor for estimation of precise outdoor performance under different average photon energies

Outdoor performance of test photovoltaic (PV) modules, especially short circuit current (ISC), is corrected to standard test conditions (STC) utilizing sc-Si PV module as PV module irradiance sensor (PVMS). In this contribution, average photon energy (APE) can be used as an index of solar spectral irradiance. The CdTe PV module was used as a test PV module since its spectrum response is significantly different from that of the PVMS to investigate an effect of spectral mismatch. The median of the error between ISC corrected to STC (ISC-correction) of CdTe PV module using PVMS and its ISC under STC is the highest at 2.64% under APE from 1.75 to 2.15 eV because of the spectral mismatch between PVMS and test PV module. On the other hand, the median of the error is obviously reduced to 0.89%, when ISC-correction was estimated using PVMS and spectral mismatch correction factor under APE from 1.75 to 2.15 eV. The lowest median of 0.54% for the error is furthermore realized under APE in a range of 1.83–1.95 eV, where spectral irradiance mostly indexed by the APE range from 1.83 to 1.95 eV (83% of all spectral irradiance) is frequently occurred at the outdoor installation site.

The History of Photovoltaics with Emphasis on CdTe Solar Cells and Modules

Among thin-film photovoltaic technology, cadmium telluride (CdTe) has achieved a truly impressive development that can commercially compete with silicon, which is still the king of the market. Solar cells made on a laboratory scale have reached efficiencies close to 22%, while modules made with fully automated in-line machines show efficiencies above 18%. This success represents the result of over 40 years of research, which led to effective and consolidated production processes. Based on a large literature survey on photovoltaics and on the results of research developed in our laboratories, we present the fabrication processes of both CdTe polycrystalline thin-film solar cells and photovoltaic modules. The most common substrates, the constituent layers, their interaction, the interfaces and the different “tricks” necessary to obtain highly efficient devices will be analyzed. A realistic industrial production process will be analytically described. Moreover, environmental aspects, end-of-life recycling and the life cycle assessment of CdTe-based modules will be deepened and discussed.

Description of short circuit current of outdoor photovoltaic modules by multiple regression analysis under various solar irradiance levels

Short-circuit current (ISC) values of test photovoltaic (PV) modules, i.e., multi-crystalline silicon, heterostructure-with-intrinsic-thin-layer, single-crystalline silicon back-contact, CuInSe2 (CIS), and CdTe modules, are descripted using multiple regression analysis based on environmental factors (solar irradiance, average photon energy (APE), and module temperature (Tmod)) under several solar irradiance levels. The APE is an index of the solar spectral irradiance distribution. PV module irradiance sensor (PVMS), single-crystalline silicon PV module, is used to investigate simultaneous solar irradiance (IrrTPVMS). It is disclosed that ISC is primarily determined by IrrTPVMS. Error between the estimated ISC and measured ISC of test PV modules is investigated. Consequently, precise ISC description (low error) is obtained when IrrTPVMS is utilized. The more precise description of the ISC for CIS and CdTe PV modules, having the bandgap (Eg) different from PVMS, is realized when adding APE environment factor even under low IrrTPVMS (≥0 kW/m2), accumulated on both sunny day and cloudy day suggesting the enhancement of investigation opportunity. This is because APE minimizes spectral mismatch error caused by Eg difference between PVMS and test PV module. Moreover, the precision of ISC description is further increased under enhanced IrrTPVMS of ≥0.5 kW/m2 (on sunny day) due to stable solar irradiance.

Optimal configuration of photovoltaic power plant using grey wolf optimizer: A comparative analysis considering CdTe and c-Si PV modules

At present, photovoltaic (PV) power plants are growing rapidly to respond to the high demand for energy. In this case, improving the levelized cost of electricity (LCOE) and produced energy for PV power plants is a complicated design tradeoff that involves several parameters, such as meteorological data variation, nonlinear operation of the PV plant components, inverter types, and PV module efficiency. Hence, this study intended to present the application of recent meta-heuristic techniques, namely, salp swarm algorithm (SSA), whale optimization algorithm (WOA), and grey wolf optimization (GWO), for two different cases. The technology of crystalline silicon (c-Si) and thin-film cadmium telluride (CdTe) PV modules is adopted for economic considerations and to determine the suitable PV module for the PV power plant. The optimization process is considered to minimize the LCOE and suggest the optimal sizing of PV modules and inverters on the basis of several candidates and their arrangement within the available area with optimal PV module tilt angle and orientation, as well as the optimal distribution of PV modules among the inverters. The new approaches have been compared with particle swarm optimization (PSO) algorithm. The proposed technique (GWO) shows significant results compared with other methods (PSO) in solving the optimal design of the PV power plant. The PV plant LCOE using thin-film (CdTe) has the lowest value compared to crystalline silicon (c-Si). The PV module efficiency and technology affect the overall dimension of the PV power plant.

Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells

Electricity produced by cadmium telluride (CdTe) photovoltaic modules is the lowest-cost electricity in the solar industry, and now undercuts fossil fuel-based sources in many regions of the world. This is due to recent efficiency gains brought about by alloying selenium into the CdTe absorber, which has taken cell efficiency from 19.5% to its current record of 22.1%. Although the addition of selenium is known to reduce the bandgap of the absorber material, and hence increase the cell short-circuit current, this effect alone does not explain the performance improvement. Here, by means of cathodoluminescence and secondary ion mass spectrometry, we show that selenium enables higher luminescence efficiency and longer diffusion lengths in the alloyed material, indicating that selenium passivates critical defects in the bulk of the absorber layer. This passivation effect explains the record-breaking performance of selenium-alloyed CdTe devices, and provides a route for further efficiency improvement that can result in even lower costs for solar-generated electricity. Selenium in cadmium telluride solar cells is known to allow bandgap engineering, thus enabling highly efficient devices. Here, Fiducia et al. show that selenium also plays a role in passivating defects in the absorber layer.

Effects of Aging and Environmental Factors on Performance of CdTe and CIS Thin-Film Photovoltaic Modules

The effects of aging and environmental factors on the performance of cadmium telluride (CdTe) and copper indium gallium selenide (CIS) thin-film photovoltaic (PV) modules have been analyzed. Recent developments in thin-film technology have resulted in reduced manufacturing costs and increased cell efficiency, making thin-film PV modules desirable for future solar-energy-generation systems. Such PV modules are currently used for various power system applications; however, their performance during the operational lifetime is greatly affected by aging and module failures caused by environmental factors. In this study, x-ray diffraction and infrared radiation imaging were used to characterize the imperfect surfaces of CdTe and CIS samples taken from a real application under various aging and environmental conditions. The performance of the modules was also evaluated by measuring the current, voltage, power, and efficiency over 3.5 years. During this period, we mainly detected corrosion, delamination, micro-cracks, and hot-spot failures. At the end of the study, the module degradation factors (MDFs) were calculated based on the measured results. The micro-crack and delamination failures resulted in MDFs of 14.49% for the CdTe modules and 21.24% for the CIS modules. With these MDFs, the installed system inevitably experienced substantial power loss in generation: 21.7% for the CdTe modules and 31.5% for the CIS modules. Consequently, our findings indicate that the performance of a PV system is susceptible to aging, meteorological conditions, and the PV technology; these factors should thus be considered before implementing PV system designs to achieve the most efficient and cost-effective power generation.

Ecological network analysis of solar photovoltaic power generation systems

Ecological network analysis (ENA) is emerging as a powerful tool for studying complex technological systems and can reveal information not captured by life cycle assessment (LCA). In this study, we developed an ENA based on the material, energy, and water life cycle inventory of CdTe photovoltaic (PV) modules. We defined one ecological (sun) and eight technological (manufacturing, construction, power grid, solar energy, fuel, water, recycling and waste treatment, and dissipation) network compartments. We studied the interactions of these compartments using throughflow analysis (TA), network utility analysis (NUA), network control analysis (NCA), and network stability analysis (NSA). The TA revealed that total throughflow of the system (TST), or quantified total size of the system is for producing 1 kWh of electricity from solar power is 604 kWh. The NUA assessed the symbiotic relationships within the system and revealed that both quantitative and qualitative beneficial relationships between compartments are prominent. Also, mutualism and synergism indexes were calculated as 2.4 and 7.0, respectively, indicating that most of the system compartments are gaining energy; thus, the system is flexible and preferable for industries when the system compartments are increasing their involvement and cycling within the system. The NCA results indicated that most of the compartments have control over the dissipation compartment, which suggested that large amounts of energy are lost in those compartments. Also, not surprisingly, almost all the compartments were dependent on fuel and water. Our NSA results showed that the current solar energy system lacks systematic diversity and resilience; it lacks the ability to return to the original state when the system is stressed. However, the main reason for these results is the low conversion efficiency of photonic energy to electricity. The same issue would apply to all other engineered power generation systems as well due to low fundamental limits of energy conversion.

Similarity of potential-induced degradation in superstrate-type thin-film CdTe and Si photovoltaic modules

Degradation phenomena under high-voltage stress, referred to as potential-induced degradation (PID) in general, were studied in superstrate-type thin-film photovoltaic (PV) modules, such as CdTe and thin-film Si PV modules. Both deterioration in the PV performance and delamination of the transparent conducting oxide (TCO) layer on the glass substrate were observed by the PID test for both PV modules, although a change in the PV parameters during the PID test with negative voltage application was somewhat different between them. It was also found for both PV modules that recovery from PID is accomplished by positive voltage application and that quick and drastic deterioration in all the PV parameters occurs by the second negative voltage application after recovery. It is suggested that the common origin of PID for superstrate-type thin-film PV modules is damage and delamination of the TCO layer.

Uniqueness verification of solar spectrum obtained from three sites in Japan based on similar index of average photon energy

The output energy yield from the photovoltaic (PV) module is influenced mainly by the spectral irradiance under outdoor conditions. To evaluate the effects upon PV modules, a quantitative index is essential for appropriate statistical analysis, because spectral irradiance distribution is a function of wavelength. Average photon energy (APE) is an index which represents a quantitative value of spectral irradiance distribution, and an APE value calculated from 350 to 1050 nm wavelength (APE350-1050) uniquely describes the shape of the solar spectrum at Kusatsu-city. Meanwhile, our previous study showed that APE has effects on PV performance, especially on short circuit current (ISC) of PV modules. Therefore, APE is a useful index of evaluation of PV performance under actual outdoor conditions. In Japan, the uniqueness of APE have been demonstrated at Ritsumeikan University in Kusatsu-city, Shiga prefecture as an index of spectral irradiance distribution and its effect on PV performance. However, the spectral characteristics in other regions of Japan with respect to Ritsumeikan University in Kusatsu-city are not yet clearly understood. This study aims to describe and discuss the uniqueness of solar spectrum obtained from three sites: Ritsumeikan University in Kusatsu-city, National Institute of Advanced Industrial Science and Technology in Tsukuba-city, and the University of Miyazaki in Miyazaki-city, Japan based on similar APE for standardization with respect to Kusatsu-city. In regard to this view, the coefficient of determination, denoted R2, was used to quantify the degree of coincidence for the shape of the solar spectrum. The results obtained from the R2 method were compared for evaluating consistency among three sites on the basis of Ritsumeikan University. It was found that the high R2 values of 0.988–0.998 correspond to small APE errors of 0.006–0.028 eV. These errors are raised from the different sites due to the slight variations in the shapes of the solar spectrum. For further evaluation of the influence of ISC of different PV modules, spectral mismatch correction factor (MM) based on the irradiance obtained from a pyranometer as a function of APE is examined and compared with three sites using similar APE. Results showed that the MM of the PV modules which have spectral sensitivities in the long wavelength band is approximately 1 regardless of the APE, except for cadmium telluride (CdTe) PV module. We thus conclude that the ISC of different PV modules except the CdTe PV module have uniqueness, if the irradiance and APE350-1050 measured from all three sites are similar.

Analysis of the behaviour of cadmium telluride and crystalline silicon photovoltaic modules deployed outdoor under humid continental climate conditions

Photovoltaic (PV) modules are the main element responsible for the harvesting of solar radiation in PV systems. Thus, their reliability and durability are two crucial factors to take in consideration for conceiving performant PV systems and improve the energy generation. The outdoor comportment analysis of different PV module technologies has gained an increased interest in last years in order to gain insight on the degradation of their performance.The present work studies the behaviour of three different PV modules based on cadmium telluride (CdTe), monocrystalline (c-Si) and multicrystalline silicon (mc-Si) technologies deployed outdoor in a humid continental climate. The period under scrutiny ranges from August 2015 to September 2017. Moreover, a new approach based on artificial neural network (ANN) was developed for the prediction of missing weather data.The obtained results showed that c-Si and mc-Si PV modules presented a slight performance degradation following the seasonal changes. The worst degradation rate of −5.55%/year was obtained for CdTe PV modules. Finally, the effects of the degradation on the I-V curve were proven by an indoor characterization of CdTe PV modules.

Daily Harvested Energy of Cadmium Telluride Thin Film Photovoltaic

The power generated by solar photovoltaic (PV) is highly affected by the weather environment. Thin-Film solar module of cadmium telluride (CdTe) is one of the Semi-transparent PV (STPV) that can be employed in a wide application range as a means to sunlight permeability while supplying solar electrical energy with some shading which also preferable in hot areas. The system behavior and the forecast of a STPV harvested energy requires an accurate and reliable discribtion for the power pattern rate during the day time. This research presents a real-time daily measurements for CdTe PV modules that serve the system design, prediction, and modeling. Multilayer and single installation categories are configured to be experimentally tested at different weather conditions (temperature and irradiance). The measurements were conducted at UPM University, Serdang, Malaysia, where a 6 different modules are expreinced. A wireless monitoring system with high sampling frequency employed for this purose. The results show an efficiency of 2.51 as a maximum in cloudy day conditions, while the harvested daily energy show that a multi-layer configuration may only be effective when the transparency is high. This new generation of PV module is similar to that for Silicon-based PV but it has threshold value to start power generating and promises for efficient sustainable building materials

Long-term Performance Analysis of CdTe PV module in real operating conditions

Solar photovoltaic (PV) technology has gained ample attention with the continuously increasing electricity demand and climate concerns. The Cadmium Telluride (CdTe) based PV technology is the leading and foremost technology among rapidly growing thin film PV industry because of its lower energy and economic payback period and energy efficiency competitive to the wafer based technology. Although, these modules undergo a series of indoor qualification tests specified by IEC61646, the long-term performance analysis in real operation conditions is essential in order to ensure long term stability, robustness and reliability. In this paper, performance analysis of 80WP CdTe PV module has been carried out on the basis of long term time series data of short circuit current (ISC) and open circuit voltage (VOC) measured in outdoor conditions. The measured electrical parameters has been translated to alternate reporting conditions i.e. 800W/m2 irradiance over the module surface and 40°C module temperature. The monthly averaged and normalized VOC and ISC of the module is found to be degraded by 2.86% and 2.29% after 23 months of outdoor exposure. The parameters are translated to standard test conditions for diurnal analysis which shows the degradation of 2.91% for VOC while no deviation in the value of ISC.

Optimization of process on electrodeposition of 4N tellurium from alkaline leaching solutions

The purification of tellurium (Te) has received considerable attention as the cadmium telluride (CdTe) photovoltaic modules have become one of the lowest-cost products of solar electricity. An optimum tellurium (Te) purification process consists impurity separation, electrodeposition, and ultrasonic cleaning was proposed first time for preparing 99.99% (4N) purity of Te from alkaline leaching solution which contains high level impurities. The main metallic impurities copper (Cu), lead (Pb), iron (Fe), and bismuth (Bi) were effectively separated from the solution by adding appropriate quantity of sodium sulfide nonahydrate (Na2S·9H2O) before electrodeposition. The impurities arsenic (As) and selenium (Se) were further removed by ultrasonic cleaning. Under the optimum process, 4N-Te powder was prepared, meanwhile, the impurity contents of Cu, Se, As, Pb, Fe, Bi, magnesium (Mg), and sulfur (S) in the Te product all met the 4N-Te standard, along with the impurity contents of As and Se in the Te product were lower than 2ppm after ultrasonic cleaning. The chemical composition of the Te product was identified by inductively coupled plasma optical emission spectrometer (ICP-OES). Furthermore, the electrochemical behavior of Te on the titanium (Ti) plate in the alkaline leaching solution was studied by linear sweep voltammogram (LSV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP). The morphology, structure and purity of Te product were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-rays (EDX). 4N-Te product with hexagonal single crystal structure was obtained by the optimum Te purification process based on electrodeposition method.

Technical and economic evaluation of thin-film CdTe building-integrated photovoltaics (BIPV) replacing façade and rooftop materials in office buildings in a warm and sunny climate

Abstract A great challenge and trend for sustainable buildings is to reduce electricity consumption, and at the same time try to supply their own energy demand with self-generation. The project should be development focused on sustainability, explore the passive strategies and the energy generation potential of facades and roof. In this paper we analyze for the first time in Brazil and under current solar photovoltaic (PV) module prices, the technical and economic potential of integrating state-of-the-art, frameless, glass-glass thin-film cadmium telluride (CdTe) PV modules on a commercial building facade and roof, and evaluate the economic feasibility of replacing traditional facade materials like architectural glass and aluminum composite material with sleek black PV modules in six Brazilian cities. The technical analysis consisted in evaluating the energy performance of a four-storey office building for each of the six cities under analysis. The technical analysis showed that it is possible to fully meet the energy demand of the office building with PV integration in all the Brazilian cities evaluated. While the local climate has a significant impact on the energy consumption due mostly to air conditioning loads, PV energy production follows the same trend. Most importantly, the economic analysis showed that with the declining costs of photovoltaics, replacing conventional facade building materials with PV modules is not only an innovative approach but also of economic benefit.