Passivated Emitter And Rear Cell Research Articles

Investigating the impact of edge passivation on shingle solar modules

This work deals with solar modules made from rectangular-shaped solar cell strips, so-called shingles, that are interconnected by overlapping one with another. For the fabrication of such modules, host solar cells are cut into several shingles resulting in unpassivated shingle cell edges and relevant recombination losses. As discussed in this work based on simulations, quantifying these losses on module level is not straightforward and is ideally done by referring to the pseudo fill factor pFF. In this context, it is shown that by passivating the cut edges of the shingles by depositing a dielectric layer, a significant pFF increase can be achieved both on shingle as well as on module level. Considering the highest respective pFF value found for modules with and without edge passivation, an increase of ΔpFF = 0.5%abs is reached. At the same time, no significant compromise of the interconnection quality is observed. These results are obtained for monofacial passivated emitter and rear cell (PERC) shingles. In short, this work is the first comprehensive analysis of experimental data on module level in the context of edge passivation. It demonstrates that the deposition of a dielectric passivation layer at the shingle's edges can boost pFF of shingle solar modules, while the current transit between the busbars of jointed shingles is not significantly hindered.

Method and Equipment for Reducing the Efficiency Degradation of Monocrystalline Passivated Emitter and Rear Cells

Infrared soldering as a step in module encapsulation, which would cause light-induced degradation (LID) and light- and elevated-temperature-induced degradation (LeTID) effects on solar cells, may cause efficiency mixing among solar cells that were originally in the same grade within the module after soldering. Furthermore, the problem of bright and dark regions would appear, which would result in a decrease in the CTM value. Current injection is considered to be one of the effective methods to solve the above problem. However, after the current injection treatment, there is still a 10% probability of the appearance of bright and dark regions in modules. In this work, we first adopted the conventional current injection process in monocrystalline passivated emitter and rear cells (PERCs). The effects of injected currents, temperature and time were systematically optimized, and cells with or without the current injection under the optimal parameters were illuminated with 1 sun at 85 °C for 25 h. Secondly, a piece of equipment was developed to further stabilize the performance of solar cells and improve the CTM value. The results showed that the best current injection parameters were a temperature of 185 °C, an injected current of 11 A and an injection time of 770 s. Compared with the cells without any pretreatment, the relative changes in the η, Voc, Isc and FF of the cells pretreated with the optimal conditions mentioned above were 0.23%, 0.08%, 0.02% and 0.08% larger, respectively, after 25 h of degradation. Then, solar cells processed by current injection were processed with our equipment, and the probability of a problem occurring was reduced from 10% to 2%. Meanwhile, the CTM value increased by 0.4%. Finally, a balance mechanism between H0 and H0-X has been proposed to explain the mechanism of the equipment.

Field performance analysis of solar cell designs

This study analyzes the field performance of various solar cell designs. Most research and development efforts concerning solar cells aim to increase their efficiency or power under standard test conditions (STC). However, conducting an actual field performance analysis is crucial because of the various ambient conditions present in the field, including temperature, irradiance, PV system installation, and albedo. These conditions can result in different performance results compared to STC. This study compares and analyzes case studies to assess field performance. One particular case study compares the field performance of monofacial modules with a monofacial passivated emitter and rear cell (PERC) and bifacial PERC at a carport system in the ambient conditions of the Korean Peninsula during summer and winter. The module material properties (white EVA and white backsheet) can impact module performance owing to the transmittance spectra at longer wavelengths. Certain transmittance values also contribute to the bifaciality number. Although the monofacial cell demonstrates better STC results, the field performance of the bifacial cell is superior in terms of energy yield and cost-effectiveness. Therefore, this study highlights the importance of considering the field performance (energy yield), in addition to STC, when designing solar cells and modules.

Performance optimization of PERC solar cells based on laser ablation forming local contact on the rear

Abstract To improve the photoelectric conversion efficiency (η) of the solar cell, a green wavelength (532 nm) laser source in a nanosecond range was used to ablate the passivated emitter and rear cell (PERC) to form the contact holes. If the laser ablation hole opening process was not set properly, the diameter or the external expansion of holes would be too large, causing the decline of the PERC performance. The Gaussian distribution of the laser is regulated by the output power (P o) and the repetition frequency (f rep) of the incident pulse laser, so that the optimized morphology of holes is obtained on the back of the PERC solar cells. After the contact holes are screen printed by the aluminum paste, the local back surface field is finally formed. The experimental results showed that the outward expansion decreases obviously with the increase of laser P o. Second, the spacing of the holes decreases with the increase of the laser f rep. It was found that under the laser P o of 33.0 W and f rep of 1,400 kHz, the η of the industrial PERC solar cells was the highest. The Quokka simulations indicated that small outward expansion, small diameter, and long spacing of holes would further decrease the recombination parameter in the rear surface. With the optimized morphology of contact holes and the low contact resistance, the PERC cell’s calculated V oc and η improvements were 6.5 mV and 0.48%, respectively, which was verified with experimental findings.

Production of upgraded metallurgical-grade silicon for a low-cost, high-efficiency, and reliable PV technology

Upgraded metallurgical-grade silicon (UMG-Si) has the potential to reduce the cost of photovoltaic (PV) technology and improve its environmental profile. In this contribution, we summarize the extensive work made in the research and development of UMG technology for PV, which has led to the demonstration of UMG-Si as a competitive alternative to polysilicon for the production of high-efficiency multicrystalline solar cells and modules. The tailoring of the processing steps along the complete Ferrosolar’s UMG-Si manufacturing value chain is addressed, commencing with the purification stage that results in a moderately compensated material due to the presence of phosphorous and boron. Gallium is added as a dopant at the crystallization stage to obtain a uniform resistivity profile of ∼1 Ω cm along the ingot height. Defect engineering techniques based on phosphorus diffusion gettering are optimized to improve the bulk electronic quality of UMG-Si wafers. Black silicon texturing, compatible with subsequent gettering and surface passivation, is successfully implemented. Industrial-type aluminum back surface field (Al-BSF) and passivated emitter and rear cell (PERC) solar cells are fabricated, achieving cell efficiencies in the range of those obtained with conventional polysilicon substrates. TOPCon solar cell processing key steps are also tested to further evaluate the potential of the material in advanced device architectures beyond the PERC. Degradation mechanisms related to light exposure and operation temperature are shown to be insignificant in UMG PERC solar cells when a regeneration step is implemented, and PV modules with several years of outdoor operation demonstrated similar performance to reference ones based on poly-Si. Life cycle analysis (LCA) is carried out to evaluate the environmental impact of UMG-based PV technology when compared to poly-Si-based technology, considering different scenarios for both the manufacturing sites and the PV installations.

Potential‐Induced Electrochemical Corrosion in Crystalline Silicon Solar Cells

In this article, the electrochemical corrosion of full‐area aluminum back‐surface field (Al–BSF) and bifacial passivated emitter and rear cell (PERC) crystalline silicon (c‐Si) solar cells subjected to different potential in sodium chloride (NaCl) solution is systematically investigated. Based on different potential‐induced corrosion, the electrochemical corrosion mechanism of c‐Si solar cells is revealed for the first time. Under zero potential, an important finding is that the silicon beneath silver electrode is corroded and perforated for Al–BSF cells. This phenomenon is attributed to the interaction between hydroxide ions from galvanic corrosion and electrons from silicon corrosion. For bifacial PERC cells, the pyramidal structure of silicon surface beneath the aluminum finger is observed at zero potential, which is similar to the silicon texturing etched in alkaline environment. Additionally, it is found that silicon corrosion is inhibited when positive or negative potential is applied to the back of Al–BSF and bifacial PERC cells. Moreover, it is observed the aluminum suffers from more serious corrosion at positive potential than that at zero or negative potential, which is attributed to synthetical results of galvanic corrosion and electrolytic corrosion. In this work, a new insight on the potential‐induced electrochemical corrosion for c‐Si solar cells is provided.

Ground-mounted or residential rooftop photovoltaic plant − European production or Chinese production: which is the most environmentally sustainable system? A case study in Italy

In recent years, decarbonization policies have pushed for a significant increase in renewable energies for power generation applications. European strategy aims to bring online over 320 GW of solar photovoltaics by 2025 and almost 600 GW by 2030. In this context, it is not only important to figure out the main hotspots of PV system but also to understand which are the best configurations from an environmental point of view. The analysis proposed in this paper aims to compare the environmental benefits of producing 1 kWh through two different system configurations: a ground-mounted PV plant (84 MW) and a residential rooftop PV plant (3 kW). In particular, the PERC (Passivated Emitter and Rear Cell) technology is investigated. In addition, in order to assess the influence of the energy mix used in the production of the PV components (mono-Si ingot, wafer, cell and module) on the LCA results, two different production sites are explored, i.e., in China and in Europe.

Enhancement of efficiency in monocrystalline silicon solar cells

As the representative of the first generation of solar cells, crystalline silicon solar cells still dominate the photovoltaic market, including monocrystalline and polycrystalline silicon cells. With the development of silicon materials and cut-silicon wafer technologies, monocrystalline products have become more cost-effective, accelerating the replacement of polycrystalline products. In addition, the conversion efficiency of monocrystalline products increases gradually through high-efficiency cell technologies such as Passivated Emitter and Rear Cell (PERC). This paper will start with the solar cell efficiency and combine cost factor, the P-type PERC cell and additional four types of high-efficiency N-type cell technologies to improve the conversion efficiency for exploration, and will analyze and predict the future solar cell industrialization technologies. The study finally concludes that the N-type Tunnel Oxide Passivated Contact solar cell technology has a large industrial potential and could become a mainstream technology after the perc cell technology. At the same time, Interdigitated back contact cell structure and selective all-passive contact technologies are reliable paths to obtain solar cells with high conversion efficiency, integrated cost, and efficiency, depending on the advantages and compatibility of various cells. It can create conditions for the industrialization of low- cost and high-efficiency monocrystalline silicon solar cells.

Investigation on temperature dependence of recent high-efficiency silicon solar modules

The temperature dependence of photovoltaic modules varies with temperature and irradiance. For recent high-efficiency solar modules such as silicon heterojunction (SHJ) solar modules and tunneling oxide passivated contact (TOPCon) solar modules, it is not clear how their temperature dependence changes with temperature and irradiance. In this study, the temperature dependence of SHJ and TOPCon solar modules was studied by measuring I–V curves with the irradiance ranging from 200 to 1000 W/m2 and temperature ranging from 25 to 75 °C. The passivated emitter and rear cell (PERC) solar modules were measured as a reference. The results indicate that the temperature dependence of short-circuit current (Isc) for the three modules is almost invariable with temperature and irradiance. The temperature dependence of open-circuit voltage (Voc) and maximum power (Pm) decreasees with the increasing module temperature, and increasees with the increasing irradiance. It can be observed that the absolute magnitude of (∂Pm/∂T)/Pm for SHJ is the smallest, which is more obvious at high irradiance. An interesting finding is that the temperature dependence of fill factor (FF) for SHJ solar module increases with increasing irradiance, which is opposite to PERC and TOPCon solar modules. This phenomenon is related to the temperature dependence of series resistance. In addition, the temperature dependence is not linear at low temperature and irradiance. The obtained results in this paper can provide useful insight into predicting performance ratio of PERC, SHJ and TOPCon solar modules.

Optical modeling and characterization of bifacial SiNx/AlOx dielectric layers for surface passivation and antireflection in PERC

AbstractIn this research, we analyzed the impact that the optical characteristics of dielectric surface passivation and antireflection coating schemes have on the performance of passivated emitter and rear cell (PERC) silicon solar cells. We employed wafer ray tracer (WRT) and automate for simulation of heterostructure (AFORS‐HET) simulations, as well as experimental characterization of fabricated thin film coatings. We investigated three distinct front surface morphologies: planar surface, upright pyramids, and inverted pyramids. Using WRT, we calculated the photogeneration current densities (JG) for PERC devices with three schemes: (i) SiNx/AlOx as antireflection coating and passivation stacks on both the front and rear sides, (ii) SiNx antireflection coating on the front side and AlOx passivation layer on the rear side, and (iii) SiNx/AlOx as antireflection coating and passivation stacks on the front side with an AlOx passivation layer on the rear side. Following simulation with optimal JG, two schemes are experimentally evaluated: PECVD SiNx (70 nm) and atomic layer deposition (ALD) AlOx (15 and 25 nm). We confirmed the growth effects and optical properties using X‐ray diffraction, Raman spectroscopy, effective lifetime, and refractive index measurements. The most favorable electrical properties were obtained with SiNx (70 nm, front) and AlOx (25 nm, front and rear), where the AlOx can be deposited via ALD bifacially on a single step, minimizing processing while maintaining passivation performance. Finally, we used AFORS‐HET to simulate the maximum performance of PERC bearing such films. The results showed a Voc = 0.688 V, Jsc = 41.42 mA/cm2, FF = 84%, and packing conversion efficiency (PCE) = 24.12% as the optimal solar cell performance values.

Theoretical analysis of backside polycrystalline silicon layer in the TOPCon solar cells

As an upgraded version of passivated emitter and rear cell (PERC) solar cells, the performance of tunnel oxide passivating contacts (TOPCon) solar cells is very dependent on the silicon oxide layer and poly-Si layer. We found that different crystallization rates or doping of germanium, carbon and other elements in poly-Si can change the band gap of poly-Si, which has an impact on the efficiency (Eff) of TOPCon solar cells. Therefore, the appropriate band gap is particularly important. At the same time, the internal defect of poly-Si also have great influence on the performance of solar cells. The simulated band diagram, charge carrier concentration and recombination rate were used to deeply explore the defect in poly-Si and the influence of poly-Si with different band gap on the performance of TOPCon solar cells.

Accelerated damp-heat testing at the cell-level of bifacial silicon HJT, PERC and TOPCon solar cells using sodium chloride

Bifacial passivated emitter and rear cells (PERC) currently have the highest share in the photovoltaic market. However, heterojunction (HJT) and tunnel oxide passivated contact (TOPCon) solar cells are expected to gain significant market share shortly. Despite technological advancements, concerns about the reliability of HJT and TOPCon technologies when deployed in the field still need to be addressed. This work investigates the impact of sodium chloride (NaCl) on damp-heat-induced degradation in bifacial HJT, PERC, and TOPCon solar cells by exposing the solar cells to NaCl before damp heat (DH) testing. It is found that among all investigated cell technologies, TOPCon solar cells degrade the most with maximum power (Pmax) loss of up to ∼75%rel, followed by HJT (Pmax drops ∼50%rel), and PERC cells (Pmax drops only ∼10%rel) after 20 h of DH testing, mainly attributed to an increase in Rs on the front side of TOPCon cells, both sides of HJT cells and the rear side of PERC cells. The front of the PERC and the rear of the TOPCon solar cell are found to be stable. The rise in Rs is attributed to the corrosion of the metal contact, which is caused by a high amount of Na+ and Cl− ions penetrating the metal contact. This corrosion leads to increased porosity, detachment of the contact from the silicon interface, and increased recombination loss in some cases. These results are crucial for all cell technologies as they highlight the potential failures that could occur in the field. Na+ and/or Cl− ions are common contaminants present in solar glass, human fingerprints, soldering flux, rainwater, soil/dust, and seawater. During field operation, these ions have the potential to penetrate and directly interact with solar cells. In our view, the preferred solution is for the solar cells to be corrosion-resistant, which can be rapidly assessed using the method presented in this work.

LeTID mitigation via an adapted firing process in p-type PERC cells from gallium-doped Czochralski silicon

In this work, we analyse the light and elevated temperature induced degradation (LeTID) behaviour of gallium (Ga)-doped Czochralski (Cz) passivated emitter and rear cells (PERC). We show that these cells, based on industrial precursors, are prone to LeTID, degrading on average 8.3%rel in efficiency. The degradation and regeneration is slower than in boron (B)-doped PERC cells leading to a greater loss of energy over a 20 year lifespan of a solar module on a German rooftop, since, according to our experiments, regeneration does not start during that time frame. We show that the method of mitigating LeTID by slightly altering the temperature profile during fast firing, previously introduced on B-doped PERC cells, also works on Ga-doped PERC cells, reducing the maximum degradation to between 1%rel and 4%rel. This process does only slightly reduce the initial efficiency of the cell by up to 0.8%rel. Lastly, we show that increasing illumination and temperature from 0.15 suns eq. to 2 suns eq. and 75 °C to 140 °C, respectively, is an adequate way to accelerate LeTID testing on Ga-doped samples by more than two orders of magnitude while achieving qualitatively and quantitatively similar results to those obtained in a standard test.

Atomic layer deposition of NiO applied in a monolithic perovskite/PERC tandem cell

Monolithic perovskite/silicon tandem photovoltaics have fueled major research efforts as well as gaining rapid industrial interest. So far, most of the literature has focused on the use of currently more expensive silicon heterojunction bottom cell technology. This work demonstrates a perovskite/silicon tandem solar cell based on the industrially dominant passivated emitter and rear cell (PERC) technology. In detail, we investigate a tunnel recombination junction (TRJ) consisting of ITO/NiO/2-(9H-carbazol-9-yl)ethyl] phosphonic acid (2PACz) and compare it with an ITO/2PACz TRJ. Specifically, the NiO layer is deposited by atomic layer deposition (ALD). Although ITO/2PACz-based tandem devices can reach more than 24% conversion efficiency, we observe that they suffer from a large spread in photovoltaic parameters due to electrical shunts in the perovskite top cell, caused by the inhomogeneity of the 2PACz layer on ITO. Instead, when ALD NiO is sandwiched between 2PACz and ITO, the surface coverage of 2PACz improves and the yield of the devices, in terms of all device parameters, also improves, i.e., the standard deviation decreases from 4.6% with ITO/2PACz to 2.0% with ITO/NiO/2PACz. In conclusion, thanks to the presence of NiO, the TRJ consisting of ITO/NiO/2PACz leads to a 23.7% efficient tandem device with narrow device efficiency distribution.

Influence of the structural differences between end-of-life Al-BSF and PERC modules on the Al leaching separation behavior

The booming global photovoltaic industry is bringing a large number of end-of-life photovoltaic (PV) modules. Achieving effective and green recovery of end-of-life PV modules is crucial to perform the energy and environmental sustainable development. The passivated emitter and rear cell（PERC) modules are the mainstream products in the current solar cell market, while the aluminum back surface field cell（BSF)modules were the mainstream products in the previous solar market. These two types of modules currently occupy the main share of the recycling market. There are several studies on the separation and recovery of valuable metals in the end-of-life PV modules. However, the influence of different cell processes and structures on the separation behavior of mainstream impurities in cells remains unclear. In this paper, the impacts of the structure of PERC and Al-BSF cells on the separation behavior of dominant Al impurity were studied. The structure and component difference between the PERC cells and Al-BSF cells was first clarified. The relationship between the loss rate of silicon wafer and the leaching rate of the aluminum back impurity was then studied. The results showed that the local contacts between the Al layer and Si wafers were primarily formed in PERC cells, in which the higher temperatures and longer leaching times were required to achieve the same Al leaching efficiency of Al-BSF cells. As for the Al-BSF modules, in order to better balance the Al separation and silicon loss rate during the alkaline leaching process, the reaction time should be set in the range of 7–10 min. The leaching rate of aluminum can reach 97.5% at 25 °C and 1 M NaOH for 10 min. After leaching, a layer of residual Si-O-Al alloy phase which is attached to the back surface of the two kinds of cell was observed. This study has a guiding significance for the green and efficient recovery of the silicon wafer in photovoltaic (PV) modules.

25.7% efficient PERC solar cell using double side silicide on oxide electrostatically doped (SILO-ED) carrier selective contacts: process and device simulation study

Passivating contacts have recently considered as a superior carrier-selective contact approach for high-efficiency silicon-based photovoltaic devices. However, the conversion efficiencies of the silicon-based passivated emitter and rear cell (PERC) are limited by contact recombination losses that reduce their performance. Therefore, we investigated a new manufacturable silicide on oxide-based electrostatically doped (SILO-ED) carrier-selective contact to suppress the contact recombination losses and reduce the saturation current density (j 0). For the first time, double side electrostatic doping is introduced to the PERC devices to form the carrier selective passivating contacts. First, a conventional PERC device was designed and the effects of surface recombination velocity (SRV) at both contacts were studied. After that, single and double SILO-ED based contacts are introduced into the device and a systematic analysis is performed to understand the tunneling phenomena and improve the conversion efficiency compared to existing PERC cells. The front SILO-ED based device with back contact SRV of 10 cm s−1 showed a power conversion efficiency of 25.4% with j 0 (14.3 fA·cm−2). In contrast, the double SILO-ED device delivered 25.7% conversion efficiency by further suppressing the j 0 to 11.8 fA·cm−2 by implementing SILO-ED approach with two different metal silicides such as erbium silicide (ErSi2) and palladium silicide (Pd2Si) on front and rear contact surface. The champion double SILO-ED PERC solar cell delivered a conversion efficiency of 25.7% with an open circuit voltage (V OC) of 742 mV. The results reported in this study would help to develop superior passivating contact-based PERC solar cells for higher efficiencies.

Strategy of Voltage Match on the Maximum Power Point for a High-Efficiency Photorechargeable Device.

A photorechargeable device can generate power from sunlight and store it in one device, which has a broad application prospect in the future. However, if the working state of the photovoltaic part in the photorechargeable device deviates from the maximum power point, its actual power conversion efficiency will reduce. The strategy of voltage match on the maximum power point is reported to achieve a high overall efficiency (ηoa) of the photorechargeable device assembled by a passivated emitter and rear cell (PERC) solar cell and Ni-based asymmetric capacitors. According to matching the voltage of the maximum power point of the photovoltaic part, the charging characteristics of the energy storage part are adjusted to realize a high actual power conversion efficiency of the photovoltaic part (ηpv). The ηpv of a Ni(OH)2-rGO-based photorechargeable device is 21.53%, and the ηoa is up to 14.55%. This strategy can promote further practical application for the development of photorechargeable devices.

Back-Contact Interdigitated Carrier-Selective Cell: Numerical Demonstration of 30 mW/cm² Output Power Density in Standard Albedo Condition

This brief proposes a new crystalline-Si (c-Si) solar cell structure, based on bifacial back-contact and carrier-selective contact solar cell technology. The proposed device, known as back-contact interdigitated carrier selective (BICS), offers the advantage of using existing c-Si solar cell structures. The bifaciality provided by the passivated emitter and rear cell (PERC), back-contact provided by interdigitated back contact (IBC), and carrier-selective contact provided by tunnel oxide passivated contact (TOPCon) are featured simultaneously. The local and full TOPCons are, respectively, applied to the emitter and back surface field (BSF) region. The proposed device has an output density of over 30 mW/cm2 under standard conditions—room temperature with a 20% albedo condition. A comparison with our previously proposed bifacial solar cell, heterojunction back contact (HBC)+, reveals the advantages of the proposed device. The proposed device is operable under a relatively low temperature under 45 °C, whereas HBC+ is suitable for higher temperatures. Therefore, the choice between the proposed device and HBC+ should be based on the climate of the installation location.

On the kinetics of high intensity illuminated annealing of n-type SHJ solar cells: 0.4%abs efficiency gain in one second

Silicon heterojunction (SHJ) solar cells are at the forefront of high efficiency industrial solar cell manufacturing. The rapid increase in efficiency compared with passivated emitter and rear cell (PERC) cells has significantly propelled commercial interest in this technology. Illuminated annealing under elevated temperatures has been shown to lead to efficiency enhancements in SHJ cells. Recently, it was observed that increasing the light intensity used during the annealing can accelerate the efficiency gains, this approach has started to be incorporated into SHJ manufacturing. In this work, we investigate the kinetics of this high intensity illuminated annealing process in the temperature range from 200 °C to 300 °C, demonstrating that the kinetics and extent of the efficiency gain strongly depend on the temperature of the process. For the first time, we show that the changes in V OC and R S , which control the efficiency enhancement, occur at different rates. Remarkably, by investigating the temperature dependence we demonstrate a process that leads to efficiency gains of >0.4% abs in only 1 s. This new understanding presents a pathway to an industrially compatible annealing approach that significantly increases the power output of SHJ modules. • Illuminated annealing can cause significant efficiency boost for SHJ cells. • Annealing temperature plays a big role in the kinetics of efficiency gain. • Efficiency gain caused by increase in VOC and reduction RS. • An efficiency increase of 0.4%abs achieved with 1 s.

Commercial carbon nanotube as rear contacts for industrial p-type silicon solar cells with an efficiency exceeding 23%

Commercially available single wall carbon nanotube (SWCNT) soots are combined with an organic passivation scheme and shown to be an efficient rear contact and alternative to ALD-Al2O3/PECVD-SiNx/laser treatment in conventional passivated emitter and rear cell (PERC) solar cells. Both low carbonaceous purity 60–70% and 95% SWCNTs are tested and a power conversion efficiency of over 23% is demonstrated. The approach is simple, scalable and completely eliminates the metal-semiconductor contact known to cause high interfacial recombination in PERC technology. A low reverse saturation current density (J0) is achieved by varying the concentration and species of SWCNTs used and a full-area back surface field on an industrial sized (275.54 cm2) solar cell is obtained.