Copper Indium Gallium Selenide Modules Research Articles

Feasibility study on thin‐film PV laminates for road integration

AbstractIntegration of photovoltaics (PV) into the built environment (BIPV) and infrastructure (IIPV) is required to increase the installed capacity of PV worldwide, while still leaving sufficient area for other land uses. Although BIPV applications have proven to play a significant role in the energy transition, road integrated IIPV concepts are less developed and bring challenges in mechanical and electrical stability and safety that still need to be addressed. In this work, the feasibility of integrating thin‐film CIGS (Copper Indium Gallium Selenide) modules into road tiles is investigated. PV road stacks were produced by gluing CIGS laminates onto concrete tiles and covering them with epoxy and glass granulates to form impact‐ and anti‐skid layers. IV (current–voltage) characteristics show that, respectively, a thin and thick epoxy layer results in 2% and 6.6% relative loss in power conversion efficiency. Although a thin protective layer would be beneficial to the power conversion efficiency of road modules, raveling tests show increased risk for electrical failure when a thin top layer is used. Pull‐off tests showed that the weakest adhesive strength (0.8 N/mm2) is between the thin‐film laminate and concrete, offering sufficient adhesive strength to at least withstand light traffic loading. Raveling and wheel tracking tests show no mass loss and only minor deformation of the stack, respectively, indicating no real risk of raveling or rutting. Thermal cycling and damp heat exposure of the PV road tiles show that yellowing of the top layers can significantly reduce performance over longer periods of outdoor operation. Damp heat exposure after mechanical loading shows no indication of moisture ingress on any of the tested configurations, suggesting the proposed CIGS laminate stack is able to withstand light traffic loading. From the measurement results, it can be concluded that thin‐film CIGS modules are mechanically and electrically suitable for road integration. Power conversion efficiencies over 12% can be attained with this technology, indicating its potential for renewable energy generation in road infrastructure. Performance stability can especially benefit from alternative top layer materials that maintain high transparency over long lifetimes. Additionally, pilot tests are required to demonstrate the potential of the technology in a controlled outdoor environment.

The Diagnosis of Shunt Defects in CIGS Modules Using Lock-In Thermography: An Empirical Comparative Study

Shunt defects are often detected in solar panels intended for photovoltaic applications. However, existing nondestructive detection technologies have certain inherent drawbacks depending on the application scenario. In this context, this paper reports a comprehensive empirical investigation into lock-in thermography (LIT) and its applicability to diagnosing shunt defects in copper indium gallium selenide (CIGS) solar modules. LIT was compared with biased thermography, and its distinctive attributes were elucidated. The comparison results demonstrate the superior capabilities of LIT at enhancing the signal-to-noise ratio, improving the visibility, resolution, and quantification of defects, and highlighting the usefulness of LIT for advanced defect analysis. We explored scenarios in which biased thermography could be appropriate despite its inherent limitations and identified conditions under which it might be preferred. The complex thermal behavior of different types of defects under various voltage conditions was analyzed, contributing to a more nuanced understanding of their behavior. Thus, integrating experimental results and theoretical understanding, we provide valuable insights and scientific guidelines for photovoltaic research. Our findings could help enhance the efficiency of defect detection in CIGS modules, highlighting the critical role of optimized thermographic techniques in developing photovoltaic technologies.

Building-integrated photovoltaics in hot climates: Experimental study of CIGS and c-Si modules in BIPV ventilated facades

Buildings, especially mid- and high-rise ones, offer the opportunity to incorporate Photovoltaics (PV) on their vertical surfaces in addition to their roofs. This is achieved through Building Integrated Photovoltaic (BIPV) solutions. Ventilated facades in buildings can facilitate PV integration and improve the envelope's thermal performance. However, research on BIPV ventilated façades is lacking in the Gulf and MENA regions. Considering the area's harsh climate, investigating these facades is critical. Therefore, the authors of this paper conducted comparative experimental research on the energy performance of BIPV ventilated facades in the hot climate of Dubai. For a year, they monitored the energy yield and temperatures of Copper Indium Gallium Selenide (CIGS) and monocrystalline silicon (c-Si) modules on the south, east, and west facades. In addition, the study analyzed the effect of the modules' characteristics, orientation, temperature, and solar angle on the energy yield. Despite the hot temperatures, the monthly area-normalized energy yields of the c-Si modules were consistently higher than the CIGS modules across all orientations, with an average difference of 13.6%. The modules in the south facade produced the highest annual yield. Also, from October to February (the coolest period), the energy yield of the south modules surpassed the east and west modules by 41.6% and 48.5%, respectively. However, from April to August (the highest energy demand period), the east and west energy yield exceeded the south by 40.9% and 32.5%, respectively. In addition, the west-facing modules experienced higher temperatures than those in the east, resulting in an average of 12% lower energy yields. Hence, the east façade has performed the second best. The west façade production, nevertheless, closely coincides with Dubai's peak periods curve. Thus, the combination of modules on the west and south facades achieved the strongest generation-consumption correlation.

Hot-spot generation model using electrical and thermal equivalent circuits for a copper indium gallium selenide photovoltaic module

Hot-spot generation is critical to the reliability and performance of copper indium gallium selenide (CIGS) solar cells; however, its occurrence mechanism has not been fully elucidated. We conducted a partial shade stress test on three large-area CIGS modules (156 cm × 62.6 cm in size, with 102 cells) connected in series. Partial shade stress can cause irreversible and unpredictable damage to the modules, and we confirmed the generation of hot spots on the shaded cells via infrared imaging. To emulate numerically the internal electrical and thermal changes in the shaded cells, we present electrical and thermal equivalent circuits based on the material properties and layered structure of the CIGS cells and modules. Furthermore, we propose a hot-spot generation model describing the irreversible damage to CIGS cells via shunt resistance degradation because the dissipated electrical power exceeds the threshold power (Pth). The current–voltage characteristics simulated by the presented method are congruent with those measured under partial shade conditions. Partial shade induces high electrical power consumption in the shaded cells, up to ~34 mW/cm2 at a 5% shade ratio, ~1,500 times higher than that in the unshaded cells. The shunt resistance is degraded to ~18.5 Ω/mm2 (only ~0.1% of the initial normal value), and the Pth-value is estimated to be ~2.4 mW/cm2 at the center of the hot-spot cells. The presented method and Pth-parameter can be used to evaluate durability with respect to the effects of partial shade stress for CIGS and various other thin-film photovoltaic cells and modules.

Performance Assessment of Four Different Photovoltaic Technologies in Poland

Due to the observed increase of photovoltaic installations capacity in Poland, the research on the performance of different modules became an important issue from the practical and scientific point of view. This paper is intended to help system planners to choose photovoltaic modules and inverters taking into account the actual operating conditions. The study is devoted to the assessment of four different technologies of photovoltaic modules: polycrystalline silicon (pc-Si), amorphous silicon (a-Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). The data was collected at a solar plant located at high latitude location, in the eastern part of Poland, during the fourth year of the plant operation. The influence of irradiance on the temperature and efficiency of modules was studied. The results show that the efficiency of the pc-Si and CIGS modules decreases with rising temperature; however, the efficiency of the a-Si and CdTe modules is more stable. The impact of changing external conditions on the inverter efficiency as well as array and system losses during various seasons of the year was shown. The inverter efficiency reaches up to 98% in summer and drops as low as 30% in winter. Small average array capture losses of 7.41 (kWh/kWp)/month (0.25 h/day) are observed for the CIGS and 10.4 (kWh/kWp)/month (0.35 h/day) for pc-Si modules. The a-Si and CdTe array losses are higher, up to 2.83 h/day for CdTe in summer. The results indicate high annual energy yields of the pc-Si and CIGS modules, 1130 kWh/kWp and 1140 kWh/kWp, respectively. This research provided new data on pc-Si and especially the performance of the thin film modules and losses in a photovoltaic installation under temperate climate.

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.

Analysis of the Conversion Efficiency of Five Types of Photovoltaic Modules During High Relative Humidity Time Periods

A total of five different types of photovoltaic (PV) modules were comparatively analyzed in terms of electrical output, efficiency, and relative efficiency losses, based on infield data collected in a temperate mountain climate, to outline the influence of the high relative environmental humidity on the PV conversion efficiency during time intervals with clear sky and low amounts of incident solar irradiance. The mono- and poly-crystalline silicon, cadmium telluride (CdTe), copper indium selenium (CIS), and copper indium gallium selenide (CIGS) modules mounted on a fixed tilted, South-oriented platform were individually monitored or in groups of modules using power optimizers. The electrical energy production, the PV conversion efficiency, and the relative efficiency losses were correlated with the weather data, and the analysis discusses the lower electrical energy output during periods with high relative air humidity. The analysis indicates that in a temperate climate, during days with high humidity intervals similar to the ones discussed in the paper, crystalline silicon modules have the lowest efficiency losses, followed by CdTe, CIGS, and CIS modules. The results can be useful for PV system designers, installers, and end-users of PV systems for a better system design and for a more accurate prediction of the daily energy production.