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Bifacial, Color-Tunable Semitransparent Perovskite Solar Cells for Building-Integrated Photovoltaics
摘要： Recently, semitransparent perovskite solar cells (ST-PSCs) have received overwhelming attention due to their potential applications in building integrated photovoltaics (BIPV) and in tandem solar cells. The best ST-PSCs, despite the high efficiency achieved, still show limited bifacial properties and lack aesthetic properties. Here, we have demonstrated efficient bifacial colorful ST-PSCs using copper thiocyanate (CuSCN), as hole transporting material, in a n-i-p architecture. The n-i-p ST-PSCs exhibit the highest reported bifacial factor of 93.7% and achieved a bifacial equivalent efficiency of 22.1% when illuminated under 1-sun standard conditions on the front side and with a reflected albedo of ~ 54.4% from the back side. We have also demonstrated that the colorful appearance of CuSCN based ST-PSCs can be easily tuned across the entire visible spectrum by tuning the ITO (or CuSCN) thickness without affecting their final efficiency. The wide colorful tunability and excellent bifacial photovoltaic behavior of CuSCN based ST-PSCs make them a promising candidate for BIPV applications.
关键词： colorful perovskite solar cell,semi-transparent perovskite solar cell,perovskite,BIPV,bifacial solar cell
更新于2025-09-12 10:27:22
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Challenges in the pre-normative characterization of bifacial photovoltaic modules
摘要： Bifacial photovoltaic (PV) technology is receiving growing interest on the market, with several companies commercializing bifacial modules alongside their conventional products, with various c-Si structures, such as PERC, PERT, HIT, IBC, etc. Current-voltage characterization of bifacial PV modules at Standard Test Conditions (STC) is challenging, as it requires an extension of the definition of STC that includes the spectral and total irradiance on the rear side of the module. Indoor characterization in principle allows the most accurate control of these quantities: the simplest procedure involves measurements of each side of the bifacial module at a time with a single light source, while carefully keeping the other side in the dark. This procedure requires attention to minimize unintended contributions to the module power from the non-illuminated side, which is associated to the reflected irradiance from surroundings, to the optical properties of the module, and to the geometrical disposition of the cells. This work revises the pre-normative activity that has led to the draft standard IEC 60904-1-2 (due for publication in 2018) and focuses on the new norm in what concerns indoor measurement with a single-source simulator. It illustrates the metrological challenges in the selection of the non-reflective material behind the non-illuminated side, and their impact to the electrical characterization of bifacial modules.
关键词： Electrical characterization,Standard Test Conditions,Solar simulators,Bifacial photovoltaic modules
更新于2025-09-12 10:27:22
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Comparative Analyses Between Two Techniques To Understand Metal-Induced Recombination Losses In Industrial N-Type Bifacial PERT Solar Cells
摘要： Due to the high cell efficiency, low Light-Induced Degradation (LID) and high bifaciality, n-type bifacial passivated emitter and rear totally diffused (PERT) solar cells are being widely researched and currently being implemented in mass production. With the improvement of dopant profiles and passivation quality, J0,emitter and J0,bsf under passivation area could reduce to lower values. However, the Voc of cell is still not high enough which may be caused by the high recombination loss under metal area. In this paper, two different methods which are suitable for low cell efficiency diagnoses are investigated and compared to evaluate the J0,metal on both boron and phosphorus doping side of solar cells. For the first method, high resistivity n-type mono wafers are prepared with double front side or rear side structure of solar cell. Four different types of metallization ratio areas are designed on the one wafer of single side. By testing the J0,total of these four area, we can fit a line of J0,total with different contact fraction, so the J0,metal can be calculated by the expression of J0,total, J0,passivation and contact fraction. For the second method, Suns-Voc and Suns-PL are used for calculation. Four types of cell structures with metal, without metal, only with front metal and only with rear metal are fabricated to measure the probed Voc and PL derived Voc either use (i) different carrier injection levels or (ii) different light illuminations. A line can be fitted under different Suns, and by contrasting the line of cell structure and other structures, J0,metal of front metal and rear metal can be calculated by the bias of these lines. By comparing this two methods, we get the boron side Ag/Al paste J0,metal and the phosphorus side Ag paste J0,metal are around 2801 fA/cm2 and 964.9 fA/cm2, respectively. By comparing this two methods, the value of second method is lower than the first method and more appropriate for IV simulation using Quokka.
关键词： Bifacial,PERT solar cell,Suns-PL,QSSPC,Suns-Voc,J0,metal
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Inline deposited PassDop layers for rear side passivation and contacting of p-type c-Si PERL solar cells with high bifaciality
摘要： We investigate stacks of aluminum oxide (Al2O3) and boron-doped silicon nitride (SiNX:B) layers for the rear side passivation and local doping of p-type silicon solar cell samples aiming for the realization of bifacial passivated emitter and rear locally diffused (biPERL) solar cells. The local p+-doped back surface field regions are formed by laser doping and are electrically contacted using commercially available screen-printed and fired silver-aluminum (AgAl) or silver (Ag) contacts. This approach is referred to as “pPassDop”. Laser doping results in highly-doped silicon with sheet resistances as low as 15 ?/sq and surface doping concentrations up to 6×1019 cm-3. Low specific contact resistances around 1 m? cm2 and 5 m? cm2 are measured for the screen-printed and fired AgAl and Ag contacts, respectively. In addition, the influence of each individual layer within the pPassDop layer stack on the doping properties is investigated. In order to separate the impact of aluminum and boron doping, firstly the influence of the Al2O3 layer thickness (0 nm, 4 nm, 6 nm) below the SiNX:B capping layer is studied. Secondly, a conventional undoped SiNX capping layer is applied on a 6 nm-thick Al2O3 layer. The roles of each dopant are studied by measuring the doping profile and contact resistivity.
关键词： SiNX:B,laser doping,bifacial PERL solar cells,pPassDop,Al2O3
更新于2025-09-12 10:27:22
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Experimental Investigation of the Shading and Mismatch Effects on the Performance of Bifacial Photovoltaic Modules
摘要： Bifacial photovoltaic (PV) modules are drawing increasing attention because of their potential in gaining extra energy from the rear-side irradiance. However, the rear-side irradiance can cause the performance of bifacial PV modules to be different from the performance of monofacial PV modules under shading and mismatch conditions. For bifacial modules, two factors can lead to the irradiance mismatch: the front-side partial shading and the rear-side irradiance inhomogeneity. This experimental work aimed to study the impact of these two factors on the performance of bifacial PV modules. The effect of front-side partial shading was investigated by comparing the electrical and thermal behavior of bifacial and monofacial PV modules under different shading conditions. The influence of rear-side irradiance inhomogeneity was investigated by analyzing the operating voltages of the solar cells in a bifacial PV module under certain typical installation conditions. To further explain the origin of the mismatch effect, a diode model circuit was applied in the analysis. The results indicate that even when the bypass diode of the bifacial PV module was activated, the shaded bifacial cells still received extra irradiance and produced higher heat. Thus, in most cases, the mismatch caused by the front-side partial shading may result in a greater reliability risk for the bifacial PV modules compared with the monofacial PV modules. For the mismatch effect of bifacial PV modules caused by the rear-side irradiance inhomogeneity, the significant reliability issues (such as reverse bias of solar cells and hotspot problems) would rarely happen, mainly because of the limited inhomogeneity of the equivalent irradiance and logarithmical increasing relationship between the voltage deviation and irradiance deviation of each solar cell.
关键词： shading effect,mismatch,thermal characteristic,Bifacial,outdoor test,photovoltaic (PV) module
更新于2025-09-12 10:27:22
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Photovoltaic systems with vertically mounted bifacial PV modules in combination with green roofs
摘要： Dependent on the specific conditions flat roofs can be well suited for the installation of large photovoltaic systems in urban areas. For urban designers also other aspects, such as the insulation of buildings, cooling, air purification and water retention play an important role besides the ecological energy generation. The combination of photovoltaics and roof greening can therefore be an interesting fusion. It combines the advantages of a green roof with the local electrical energy production at the place of consumption. However, using a conventional photovoltaic system with tilted modules in south or east-west direction on a green roof causes problems, as typical low tilt angels and high ground coverage rates result in an almost complete coverage of the roof surface. Plants, growing in between the covered areas provoke undesirable shading of the collector surface. Only a frequent maintenance procedure, complicated by dense PV system layouts, can avoid a reduction of the energy yield in the course of time. Vertically mounted specially designed bifacial modules are an option to realize photovoltaic power generation in combination with a functional green roof at low maintenance costs. In this paper, we report on the layout and the energy yield of a corresponding system. Custom-made bifacial modules with 20 cells were produced and vertically installed in landscape orientation. The narrow layout of the modules lowers the wind load and reduces the visibility. The enhanced power in the morning and evening of vertically east-west installed modules can additionally lead to higher self-consumptions rates. Despite having some shading and undergrounds with albedo factors of less than 0.2, the bifacial installation with a rated power of 9.09 kWp achieved a specific yield of the 942 kWh/kWp in one year (11.08.2017–10.08.2018). This is close to typical values of 1000 kWh/kWp achieved for south-facing PV systems in the same region. The impact of the greening on the albedo and the system performance is investigated in more detail with two smaller sub-systems. The energy yields of the two bifacial sub-systems are compared to a monofacial, south-facing reference module. The use of silver-leaved plants in this system resulted in higher albedo values and a more resilient roof greening.
关键词： PV system,Bifacial,Albedo,Urban areas,Vertical,Green roof
更新于2025-09-12 10:27:22
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Computational Modelling of Monolithically Stacked Perovskite/Silicon Tandem Solar Cells Using Monofacial and Bifacial Designs
摘要： As the efficiency of conventional silicon (Si) solar cell is reaching closer to its thermodynamic limit, its tandem integration with emerging perovskite (PVK) solar cell is being widely explored. In this work, we use self-consistent optical and electrical simulations to computationally explore monolithically stacked 2-terminal (2-T), 2-junction (2-J) PVK/Si tandem solar cell. The optical model is based on Lambert-Beer Law while electrical model is based on drift-diffusion approach. The tandem solar cell is explored for both monofacial and bifacial configurations. The simulations show that the cell design for optimal operations is highly dependent on perovskite thickness and albedo. Under optimal design, the bifacial PVK/Si tandem cell exhibits ?? ≈ 33% for average earth albedo of 30%. Moreover, the cell exhibits a remarkable temperature coefficient of ~ ? 0.27%. Moreover, our simulation results are in good agreement with both experimental and highly intensive optical model based simulation data. With our computationally inexpensive optical model, the optimal cell design for different tandem structures can be explored in a much easier way.
关键词： monolithic,perovskite,Albedo,bifacial,current-matching,optical model,tandem
更新于2025-09-12 10:27:22
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Potential-Induced Degradation of Bifacial PERC Solar Cells Under Illumination
摘要： Bifacial passivated emitter and rear cell (PERC) solar cells are promising candidates to reduce levelized cost of electricity since a rear-side power gain can be achieved with minor changes in cell production. However, in addition to the potential-induced degradation of the shunting type (PID-s), some bifacial solar cells may exhibit another degradation related to their rear side. Using three types of purchased industrial bifacial PERC cells encapsulated in our laboratory, we show that a rear-side PID test under simultaneous illumination can cause up to 14% power degradation, which is related to increased carrier recombination at the rear side of the cell. Thus, we ?nd that the degradation under realistic ?eld conditions is strong enough to signi?cantly reduce the bifaciality gains. This is of particular importance as only some of the investigated cells recover under dark conditions. Microstructural analysis of the PID-stressed rear side reveals localized permanent structural damages of the passivation layer leading to an increased rear-side recombination.
关键词： silicon corrosion,Bifacial solar cell,potential-induced degradation,passivated emitter and rear cell (PERC)
更新于2025-09-11 14:15:04
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High-efficiency n-type silicon PERT bifacial solar cells with selective emitters and poly-Si based passivating contacts
摘要： Bifacial crystalline silicon (c-Si) solar cells have currently attracted much attention due to the front high-efficiency and additional gain of power generation from the back side. Here, we have presented n-type passivated emitter and rear totally-diffused (n-PERT) bifacial c-Si solar cells featuring front selective emitter (SE) and polysilicon (poly-Si) based passivating contacts. The SE formation was scanned with laser doping based on front boron-diffusion p+ emitter. The poly-Si based passivating contacts consisting of nano-layer SiOx of ~1.5 nm thickness grown with cost-effective nitric acid oxidation and phosphorus-doped polysilicon exhibited excellent passivation for high open-circuit voltage. We have successfully achieved the large-area (156 × 156 mm2) n-PERT bifacial solar cells yielding top efficiency of 21.15%, together with a promising short-circuit current density of 40.40 mA/cm2. Theoretical calculation has further demonstrated that the optimal thickness of SiOx nano-layer will increase from 1.5 nm to 1.8 nm if the density of interface defect state decreases by one magnitude from 1 × 1010 cm?2/eV, and the cell efficiency can be improved up to 24.64% with open-circuit voltage over 0.720 V by optimizing the parameters of functional materials and interface layers. The present work has indicated that the commercialization of low-cost and high-efficiency n-PERT bifacial c-Si cells is possible due to the processes compatible with existing production lines.
关键词： n-PERT bifacial,Nano-layer SiOx,Poly-Si based passivating contacts,c-Si solar cells,Selective emitter
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Concentrator bifacial crystalline silicon solar cells with Al-alloyed BSF and Ag-free multi-wire metallization
摘要： We present Ag-free low-concentrator bifacial indium-fluorine-oxide (IFO)/(n+pp+)Cz-Si/indium-tin-oxide (ITO) solar cells based on: (i) a shallow phosphorus-doped n+-emitter; (ii) an easy-to-fabricate screen-printed Al-alloyed Al-p+ back-surface-field (BSF); (iii) transparent conductive IFO and ITO layers grown by ultrasonic spray pyrolysis, which act as passivating and antireflection electrode; (iv) Ag-free multi-wire metallization of copper wire attached by the low-temperature lamination method simultaneously to the front IFO layer, rear ITO layer as well as to the interconnecting ribbons arranged outside the structure using transparent conductive polymer films. For the manufacture of solar cells, we used standard commercially available SiNx/(n+pp+)Cz-Si/Al structures. After removal of the residual Al paste, the Al-p+ layer was thinned by one-sided etchback process. A number of solar cells were prepared differing in the sheet resistance of the Al-p+ layer (Rp+), which ranged from 14 ?/sq (original, non-etched Al-p+ layer) to 123 ?/sq. It was found that thinning of the Al-p+ layer (increase in Rp+) greatly improved all the parameters of solar cells. The cell with Rp+ = 81 ?/sq showed the best combination of conversion parameters. Under 1-sun front/rear illumination, the conversion efficiency of this cell is 17.5%/11.2% (against 16.0%/7.5% for the cell with Rp+ = 14 ?/sq). At 1-sun front illumination and 20/50% albedo of 1-sun illumination, the equivalent efficiency is equal to 19.9%/23.5% (against 17.7%/20.1% for the cell with Rp+ = 14 ?/sq). At a sunlight concentration ratio (kC) of 2.3–2.7 suns, the cells with Rp+ in the range 45–123 ?/sq showed approximately similar maximum front-side efficiency, 17.5–17.9%. However, the operating range of sunlight concentration ratio (kC,OR) determined as η(kC,OR) = η(kC = 1) showed a tendency to decrease from 5.8 ± 0.6 suns to 4 ± 0.5 suns with an increase in Rp+ from 14–45 ?/sq to 63–123 ?/sq.
关键词： Ag-free,multi-wire metallization,crystalline silicon,Al-alloyed BSF,bifacial,solar cells
更新于2025-09-11 14:15:04