javascript:void(0) In the international photovoltaic market, the "carbon footprint" label has received great attention, and low-carbon footprint products are widely popular. Compared with metallic silver, copper has the characteristics of low carbon emissions and low cost, which can effectively reduce the carbon footprint. Based on this, this article reports a horizontal double-sided Copper metallisation technology. This technology can not only metallize the front and back sides of various types of silicon solar cells at the same time, but also has fast speed, good uniformity, and simple process, making it suitable for the industrial mass production of solar cells. This article describes the structure and manufacturing process of TOPCon solar cells patterned with ultrashort pulse laser and metallized using this novel horizontal double-sided copper metallisation technology. In this batch, average efficiency reached above 26%.

A new thermodynamic limit for the open circuit voltage of solar cells that includes thermalization is obtained in terms of photon entropy. A simple graphical construction makes it possible to link this limit to the existing limits for single junction cells due to Trivich and Flinn, Shockley and Queisser and Würfel, and the thermodynamic Carnot-type limit for hot-carrier solar cell. At the fundamental level, this limit points to similarity between photovoltaic and thermoelectric energy conversion.

It is common practice in PV system simulation to use the De Soto model, which describes how to use the 1-diode equivalent circuit model for modules. De Soto’s model scales the shunt with irradiance, making it disappear towards zero W/m 2. Also, the commercial software PVsyst uses a parameterization that reduces the shunt effect when the irradiance goes down. However, the Si solar cells that make up a module typically do not have an illumination dependent shunt. We therefore investigate the origin of the intensity dependent apparent shunt in modules. We show that this apparent shunt (derived from the slope of the quasi-linear region from I SC onwards) is a misinterpretation and has little to do with a shunt conductance. Instead, the module I- V curve slope of the quasi-linear region from I SC onwards stems from I SC mismatches between the cells. Such mismatch can occur from small illumination inhomogeneity or cell production variation. Abandoning the practice of using the I- V curve slope to determine the shunt value for equivalent circuit models of modules (and the corresponding shunt scaling in the De Soto model or PVsyst), contributes to physically more meaningful I- V curve parameterizations and possibly also more accurate PV system energy yield prediction.

Tunnel oxide passivated contact TOPCon is poised to emerge as the predominant technology in photovoltaic (PV) cells, yet significant reliability issues remain unresolved. This study conducts a comparative analysis of 20 TOPCon PV module types, utilizing a range of electrical characterization and accelerated aging assessments. This investigation provides a detailed evaluation of the electrical performance, resulting in an Energy Rating of the modules, establishing a benchmark for cutting-edge TOPCon technology. While some failure modes, such as LeTID, appear to be non-critical, the findings confirm previously identified degradation pathways in TOPCon modules due to moisture penetration. During UV exposure, a novel degradation pattern was observed during the indoor tests, showing severe losses (up to -12% after 120 kWh/m 2), followed by recovery after humidity freeze-testing, which may influence outdoor performance and the outcomes of certification tests (IEC61730-2, Sequence B). The results highlight the areas of need for more targeted testing and technological refinement.

A simple binary antimony selenide (Sb 2Se 3) absorber is evolving as an alternative photovoltaic material in thin film solar cells because of its unique properties and easy processing. Sb 2Se 3 thin films having good crystalline quality are grown via versatile thermal evaporation from pre-synthesized near stoichiometric compound material on molybdenum coated soda lime glass (SLG) and borosilicate glass (BG) substrates. Following the systematic characterizations on the absorber films, substrate configured Sb 2Se 3/CdS heterojunction devices were fabricated and their photovoltaic characteristics have been studied using current density vs voltage (J-V), dark J-V modelling, external quantum efficiency, capacitance vs voltage measurements. The power conservation efficiency values of 4.88 % and 5.04 % were achieved for the devices fabricated on SLG and BG, respectively. The obtained values are higher in comparison to the reported device efficiencies in substrate configured Sb 2Se 3 solar cells, in which the absorber is prepared through thermal evaporation. To understand the loss in open circuit voltage , a compact equivalent circuit model was considered to identify the shunt leakage pathways. In addition to that the device fabricated on the SLG were structurally stable with minimal changes in its performance for a period spanning over 200 days. The results obtained are encouraging with scope for improving the device performance through interface engineering and back surface passivation strategies.

The IEC 61853 standard series define the Climate Specific Energy Rating (CSER) which can be used within the Photovoltaic (PV) community as a reliable and accurate tool to predict a PV module’s energy output for specific climate and allows to differentiate between PV modules according to their specific performance for representative locations. The CSER power rating parameter is assumed to represent the PV device performance in real-world operation. So far, research has mainly focused on the implementation of different algorithms to determine the input parameters and to calculate the CSER values based on indoor measurement performance rating data. There is lack of information and technical specification how to obtain these parameters from outdoor field operating PV module data that reflects better the module performance behaviour. In the present study, we analysed long-term outdoor field data for a period of 36 consecutive months of a PV module in order to understand how the length (and seasonality) of the data acquisition period impacts the reliability of irradiance and temperature power matrix values, particularly in relation to CSER calculations. The PV outdoor performance data has been validated against its indoor counterpart. The results concluded that a period of 9 or 12 months provides a good compromise between accuracy and time-resources. This may be reduced to 6-month provided the meteorological conditions are sufficiently diverse in this time frame. The study provides important insights to the PV community since the CSER parameter may become a compulsory requirement for each PV module produced, imported or sold in Europe if the potential EU Ecodesign Directive and the Energy Labelling Regulation will be implemented.

not-yet-known not-yet-known not-yet-known unknown Silicon heterojunction technology (HJT) and tunnel oxide passivated contacts (TOPCon) solar cell technologies are expected to dominate the photovoltaic market in the coming years. However, there are still some concerns about the long-term stability of these technologies. This work examines the effects of two widely used commercial soldering fluxes (Flux A and Flux B) on the stability of commercial silicon HJT and TOPCon solar cells. The soldering flux was applied to the solar cells, and the solar cells were annealed at 85 oC under low relative humidity. TOPCon solar cells were found to be stable; however, significant degradation was observed in the HJT solar cells after only 50 hrs. The efficiency of the HJT cells decreased by ~ 61% rel with Flux A and ~ 55% rel with Flux B, respectively. We attribute part of the observed degradation to holes present in the HJT cell metalisation after printing, which allow the soldering flux to easily penetrate the contact and subsequently react with the paste constituents. In addition, we find that the indium tin oxide (ITO) layer is very sensitive to soldering flux, showing major cracks and significant peeling after 50 hrs of annealing. Consequently, this work shows that some soldering flux can react with the ITO layer, without requiring the presence of water. This suggests that certain types of soldering flux can harm HJT solar cells even after encapsulation without the need for moisture ingress. Therefore, paying more attention to the choice of soldering flux is essential, especially when working with HJT cells. It is strongly recommended that users perform comprehensive component analysis testing on soldering fluxes before their official use rather than solely relying on datasheets provided by suppliers.

A document by Aline Kirsten Vidal de Oliveira. Click on the document to view its contents.

We investigate rapid thermal processing (RTP) as alternative to the prolonged thermal annealing process used to form tunnel-oxide passivating contacts for silicon solar cells. The thermal treatment is generally followed by hydrogenation to passivate defects at the Si/SiOx interface. Whereas industrial manufacturing generally uses Cz wafers, research is often carried out with FZ wafers. Both types of wafers are prone to the formation of thermal defects in the bulk. To disentangle effects of the interface and the bulk, we assess the lifetime at different steps of the process sequence for both wafer types. We find that the initial bulk lifetime of our p-type FZ material is maintained for RTP up to temperatures of about 450°C, followed by a severe decay and eventually a moderate extent of recovery at temperatures above 800°C. Compared to FZ material, the initial bulk lifetimes in our p-type Cz material are slightly lower, but they are maintained on that level up to about 600°C. Beyond that temperature, the lifetimes also decay, but to a lesser extent than in the FZ material, and there is no curing at higher temperatures. Hydrogenation can partially passivate the bulk defects in FZ material, but the initial state is not recovered. In Cz material, it appears that RTP creates two different types of defects; for those created up to 800°C the initial state can be recovered by hydrogenation whereas those created at higher temperature cannot be passivated by hydrogenation. We also investigate the formation of n-type passivating contacts by RTP, and we fabricate solar cell precursors with a single RTP step and the same hydrogenation for both contact polarities. After sputtering a transparent conducting ITO layer on the full area and an Ag metallization, we achieve solar cells efficiencies up to 20.5%.

In this work, we demonstrate the formation of local boron doped, p+ SiO x/ poly-Si structures using wet chemical etching by direct printing of boron-ink FlexTrail printing. This process is a mask free approach for the formation of local TOPCon structures for high efficiency tunnel oxide passivated contact (TOPCon) solar cells. Factors affecting the etch back selectivity between intrinsic and boron doped poly-Si are studied. It is found that pre-treatment by diluted HF (1 wt%) before poly-Si removal by a KOH solution is the most crucial process to ensure etch selectivity. Etching the native oxide on intrinsic and keeping the boron silicate glass (BSG) layer on p+ poly-Si is the optimum condition for removing intrinsic poly-Si while having p+ TOPCon structure. Line widths in the range of of 86-100 µm and 24-40 µm were achieved on planar and textured surfaces, respectively. FlexTrail printing allows for significantly lower (and higher) feature sizes, but its fine-line potential wasn’t fully exploited here for alignment reasons of post-processing. Test structures with a line grid of local TOPCon structures featured a maximum open circuit voltage ( iV OC) value of 720 mV and lowest saturation current density of local p+ SiO x/ poly-Si (J 0SE) ~ 90-120 fA/cm 2. The developed local p+ poly-Si will be integrated in high efficiency TOPCon solar cell where p+ poly-Si will be placed under the metal contact in the very near future.

This study uncovers the impact of geographic variability on the distribution of sunlight on vehicle surfaces, focusing on two distinct scenarios: the flat-surface cargo area of a small delivery truck and the entire body of a commercial passenger vehicle. We employ a commuter pattern driving profile in Germany and a broader analysis incorporating random sampling of various road types and locations across Europe and the USA using LIDAR-derived topography and OpenStreetMap data. Our findings reveal significant irradiation inhomogeneity patterns shaped by the geographic landscape, road configurations, urban planning, and vegetation. The research identifies topography as the primary factor affecting irradiation distribution uniformity, with the vehicle’s surface orientation and curvature serving as secondary influencers. These insights hold immense potential for improving the design and efficiency of vehicle-integrated photovoltaic systems, presenting a foundational knowledge base from which to optimize energy capture in diverse environmental conditions.

The antireflection(AR) coating applied to solar glass in photovoltaic modules has remained largely unchanged for decades, despite its well-documented lack of durability. Traditional porous structured single-layer AR coatings last as little as 5 years in the field. In this paper, we propose a novel 5-layer dense AR coating design that offers improved durability and effectiveness compared to traditional coatings. This paper provides detailed insights into the development and characterization of the novel 5-layer AR coating, providing guidance to the photovoltaic community seeking to improve the efficiency and longevity of solar modules.

We present an analysis of the performance data of a monitored PV system onboard a light commercial electric vehicle during parking and driving conditions. The PV system’s nominal power is 2180 WP with flat silicon modules on the vehicle’s roof, rear, left, and right sides, as well as other electronic components needed to charge the vehicle’s high-voltage (HV) battery. The analysis indicated that after 488.92 hours of operation, the modules mounted on the vehicle roof produced 133.32 kWh of electricity during parking compared to 15.4, 30.67, and 22.99 kWh for the modules mounted on the rear, left, and right sides, respectively. During the trips, after 31.99 hours of operation, 6.12, 0.68, 1.08, and 1.86 kWh of electricity were produced by the modules on the roof, rear, left, and right sides, respectively. The overall system efficiency was in the 60-65 % range. The aggregated usable electricity reaching the HV battery after multiple conversion stages generated by the system at the two parking locations was 129.39 kWh. PV electricity generated at the two parking locations enabled a range extension of approximately 530 km, which is 30% of the total distance driven during the measurement period between April and July 2021.

Daylight photoluminescence imaging of crystalline silicon photovoltaic modules is demonstrated for modules embedded in rooftop and utility-scale systems, using inverters to electrically switch the operating point of the array. The method enables rapid and high-quality luminescence image acquisition during the day, unlocking efficient performance and quality monitoring without the need to connect specific electrical hardware or to make any modifications to the system wiring. The principle of the measurement approach is discussed and experimental results from a 10 kW DC residential rooftop system and from a 149 MW DC utility-scale photovoltaic power plant are presented. Measurements were performed using commercial inverters without modifications to the inverter hardware or firmware. In the case of the utility-scale power plant, the daylight photoluminescence image acquisition of modules connected to a central inverter was obtained from a remote piloted aircraft. Data analysis includes the conversion of photoluminescence image data into implied voltage differences.

This study presents a comprehensive multidisciplinary review of autonomous monitoring and analysis of large-scale photovoltaic (PV) power plants using enabling technologies, namely artificial intelligence, machine learning, deep learning, internet of things, unmanned aerial vehicle, and big data analytics, aiming to automate the entire condition monitoring procedures of PV systems. Autonomous monitoring and analysis is a novel concept for integrating various techniques, devices, systems, and platforms to further enhance the accuracy of PV monitoring, thereby improving the performance, reliability, and service life of PV systems. This review article covers current trends, recent research paths and developments and future perspectives of autonomous monitoring and analysis for PV power plants. Additionally, this study identifies the main barriers and research routes for the autonomous and smart condition monitoring of PV systems, to address the current and future challenges of enabling the PV terawatt transition. The holistic review of the literature shows that the field of autonomous monitoring and analysis of PV plants is rapidly growing and is capable to significantly improve the efficiency and reliability of PV systems. It can also have significant benefits for PV plant operators and maintenance staff, such as reducing the downtime and the need for human operators in maintenance tasks, as well as increasing the generated energy.

Levelized cost of electricity (LCOE) is a crucial metric for assessing the socio-economic cost-efficiency potential of various energy sources including solar photovoltaics. Nevertheless, accurate LCOE estimations for commercialized high-efficiency Si solar modules with passivated emitter and rear cell (PERC) and silicon heterojunction (SHJ) structures have been lacking. In this study, we present the first global LCOE estimates for a PERC module (20% cell efficiency) and a SHJ module (23% cell efficiency), which have been derived by (i) performing rigorous energy-yield calculations with full-spectral and temperature-dependent simulations that incorporate all essential meteorological effects and (ii) considering country-specific capital costs and discount rates. Moreover, to determine the universal global LCOE, the LCOEs for three distinct installation capacities (100 MW for a utility, 500 kW for a commercial, and 5 kW for a residential system) have been unified by selecting an appropriate system size at each location based on a population density. We find that the LCOEs of both PERC and SHJ systems are below 3 cent/kWh in 2020 US dollar in many areas of China, Saudi Arabia, the United States, Australia, Chile, and Botswana where the conditions of a high energy yield, low population density, low capital cost, and low country-risk premium are satisfied simultaneously. In contrast, many European countries exhibit a moderate LCOE of 3~5 cent/kWh. Notably, Japan and Russia exhibit quite high LCOEs (6~10 cent/kWh) primarily due to significantly higher installation costs and moderate energy yields. Importantly, the global LCOEs of the PERC and SHJ modules are quite similar, with the SHJ module showing a slightly better cost performance in the regions near equator due to its low temperature coefficient. Conversely, the PERC module demonstrates cost advantage in the northern hemisphere due to a lower module cost.

As the efficiency of perovskite silicon tandem solar cells is increasing, the upscaling for industrial production is coming into focus. Spatially resolved, quantitative, fast, and reliable contactless measurement techniques are demanded for quality assurance and to pinpoint the cause of performance losses in perovskite silicon tandem solar cells. In this publication we present a measurement method based on spectrally integrated photoluminescence (PL) imaging to extract subcell-selective implied open-circuit ( i V oc ) images from monolithic perovskite silicon tandem solar cells. We validate the approach using spectrally resolved absolute PL measurements based on an integrating sphere for the perovskite top cell and PL-calibrated carrier lifetime images for the silicon bottom cell. Additionally, V oc measurements of solar cells with low contact losses are used to validate the new measurement technique. We find a good agreement of the i V oc images with the validating measurements with a maximum deviation of well below 1 % compared to the validation measurements.

This paper provides a comprehensive assessment of the up-to-date life-cycle sustainability status of cadmium-telluride based photovoltaic (PV) systems. Current production modules (Series 6 and Series 7) are analyzed in terms of their energy performance and environmental footprint and compared with the older series 4 module production and current single-crystalline-silicon (sc-Si) module production. For fixed-tilt systems with series 6 modules operating under average US irradiation of 1800 kWh/m 2/yr, the global warming potential (GWP) is reduced from 16 g CO2 eq/kWh in Series 4 systems to 10 CO2 eq/kWh in Series 6 systems. For operation in US-SW irradiation of 2300 kWh/m2 the GWP is reduced from 11 CO2eq/kWh to 8 CO2eq/kWh and for 1-axis tracking systems operating in Phoenix, Arizona with point-of array irradiation of 3051 kWh/m 2/yr the GWP is reduced to 6.5 CO2 eq/kWh. Similar reductions have happened in all environmental indicators. Energy payback times (EPBT) of currently installed systems range from 0.6 years for fixed-tilt ground-mounted installations at average U.S. irradiation at latitude tilt installations, to 0.3 years for one-axis trackers at high US-SW irradiation, considering average fossil-fuel dominated electricity grids with fuel to electricity conversion efficiency of 0.3. The resulting energy return on energy investment (EROI) also depends on the conversion efficiency of the electricity grid and on the operation life expectance. For a 30-year operational life and grid conversion efficiency of 0.3, EROI ranges from 50 (at US average irradiation) to 70 for US-SW irradiation. The EROI declines with increased grid conversion efficiency; for CdTe PV operating in south California with grid conversion efficiency of 49% the EROI is about 50 and is projected to fall to 30 when the state’s 2030 target of 80% renewable energy penetration materializes. Material alternatives that show a potential of further reductions in degradation rates and materials for enhanced encapsulation that would enable longer operation lives are also been investigated. A degradation rate of 0.3%/year, which has been verified by accelerated testing, is assumed in 30-year scenarios; this is projected to be reduced to 0.2%/yr in the near-term and potentially to 0.1%/yr in the longer term. With such low degradation rates and enhanced edge-sealing, modules can last 40- to 50-years. Consequently, all impact indicators will be proportionally reduced while EROI will increase.