Commercial Monocrystalline Silicon Solar Cells Research Articles

Washable textile embedded solar cells for self-powered wearables

PurposeSolar cells could make textile-based wearable systems energy independent without the need for battery replacement or recharging; however, their laundry resistance, which is prerequisite for the product acceptance of e-textiles, has been rarely examined. This paper aims to report a systematic study of the laundry durability of solar cells embedded in textiles.Design/methodology/approachThis research included small commercial monocrystalline silicon solar cells which were encapsulated with functional synthetic textile materials using an industrially relevant textile lamination process and found them to reliably endure laundry washing (ISO 6330:2012). The energy harvesting capability of eight textile laminated solar cells was measured after 10–50 cycles of laundry at 40 °C and compared with light transmittance spectroscopy and visual inspection.FindingsFive of the eight textile solar cell samples fully maintained their efficiency over the 50 laundry cycles, whereas the other three showed a 20%–27% decrease. The cells did not cause any visual damage to the fabric. The result indicates that the textile encapsulated solar cell module provides sufficient protection for the solar cells against water, washing agents and mechanical stress to endure repetitive domestic laundry.Research limitations/implicationsThis study used rigid monocrystalline silicon solar cells. Flexible amorphous silicon cells were excluded because of low durability in preliminary tests. Other types of solar cells were not tested.Originality/valueA review of literature reveals the tendency of researchers to avoid standardized textile washing resistance testing. This study removes the most critical obstacle of textile integrated solar energy harvesting, the washing resistance.

Nanoscale TiO2 and Ta2O5 as efficient antireflection coatings on commercial monocrystalline silicon solar cell

In this paper, we report the enhancement of photon to electron conversion efficiency of commercial monocrystalline silicon solar cells after deposition of nanoscale TiO2 and Ta2O5 as an antireflection coating. The nanoscale TiO2 and Ta2O5 ARC’s remarkably enhanced PEC efficiency of m-Si solar cells from 17.18% to 17.87% and 18.8% respectably. The enhancement in PEC efficiency is predominantly attributed to the increase in fill factor from 36.8% to 36.9% and 37.2% after deposition of nanoscale TiO2 and Ta2O5 as ARCs respectively. The reflectance of nanoscale TiO2 ARCs increased from 27% to 43% within the wavelength range from to 530 nm and decreases to 34% with increasing wavelength. However, for Ta2O5 the reflectance was 11% at 370 nm and increased up to 29% in the studied wavelength range. The reduced magnitude of reflectance for Ta2O5 throughout the studied wavelength resulted in notable improvement of PEC efficiency compared to TiO2. The phase formation of nanoscale TiO2 characterized by x-ray diffraction reviles the presence of both anatase and rutile phase TiO2 whereas Ta2O5 displays amorphous nature. The oxidation state of titanium (Ti) and tantalum (Ta) was evaluated from x-ray photon emission spectroscopy and observed to be in the form of Ti4+ and Ta5+ chemical state. The nanoscale thickness of both TiO2 and Ta2O5 ARCs was acquired by variable angle spectroscopic ellipsometry and found to be 55.2 nm and 70.8 nm respectively, and the same was confirmed by measuring cross-section thickness of ARCs using a scanning electron microscope.

Optical Transparent Antenna Array Integrated With Solar Cell

This letter presents an optical transparent antenna array integrated with solar cell. Metal-meshed structure is used in the transparent antenna array, which achieves a balance between radiation efficiency and optical transparency. The meshed patches have equidistant distribution in the array and are fed by coaxial probes. A meshed ground, which has the same grid size as the meshed patch, is introduced and aligned with the patch. Cheap coating technology is utilized in printing silver-meshed patch and ground on the two surfaces of a glass substrate. A commercial monocrystalline silicon solar cell is closely assembled under the transparent antenna array. The proposed antenna array operates from 8.51 to 9.10 GHz (VSWR $\leq 2$ ) with low cross-polarization levels, and obtains an 88% optical transparency. The transparent antenna array achieves a good radiation performance with little effect on solar photovoltaic generation.

Visualizing light trapping within textured silicon solar cells

Random pyramids are the most widely used texture in commercial monocrystalline silicon solar cells to trap weakly absorbed photons with near-bandgap energies. There has been steady improvement in efforts to model the light-trapping performance of random pyramids, including a shift from an assumed pyramid base angle of 54.7° (ideal-random pyramids) to smaller values that are consistent with measured average angles. However, simulations have not yet considered the effects of a distribution of base angles (real-random pyramids), which all real textured wafers have. In this contribution, we benchmark the light-trapping capability of real-random pyramids against ideal-random pyramids and Lambertian scatterers by performing ray tracing of an accurate three-dimensional topographical map of the surface of a textured silicon wafer measured using atomic force microscopy. The angular distribution function (ADF) of light rays within the wafer, calculated at each pass as rays bounce between the front and rear surfaces, reveals that real-random pyramids are superior to ideal-random pyramids in trapping light precisely because of the distribution in their base angle. In particular, the ADF inside a wafer with real-random pyramids evolves to be Lambertian within just two passes—by the time (non-absorbed) light re-arrives at the front surface. Furthermore, the total path-length enhancement of light reaches nearly 60—exceeding that of a wafer with Lambertian surfaces—for narrow angles of incidence, though it falls short of the Lambertian reference for oblique angles.

Optimization of large-size glass laminated luminescent solar concentrators

Luminescent solar concentrators (LSCs) offer an attractive approach to combine spectral and spatial concentration of both direct and diffuse light without the expensive tracking system. In this study, different size glass laminated luminescent solar concentrators (GL-LSCs) of 7.8×7.8cm2, 15.6×15.6cm2, 31.2×31.2cm2 and 61×122cm2 were fabricated by using fluorescent dyes Lumogen Red 305 and Yellow 083, ultra-white glass and commercial mono-crystalline silicon solar cells. With the size increase, the output power of the GL-LSCs increases, but the power conversion efficiency (PCE) decreases rapidly due to the transport losses and re-absorption of luminescent materials. As a result, a series of GL-LSCs with bottom-mounted PV cells were fabricated to enhance the PCE. The relationship between the area of luminescent waveguide and the gain of the bottom-mounted PV cells was investigated for the optimization of the GL-LSCs performance. Among them, a highest gain of 1.38 in power over the bare PV cells was obtained with PV cell coverage of 4.54%. A highest PCE of 2.28% was achieved with PV cell coverage of 11.32%. It was found that the design with PV cell coverage of 9.07% have the lowest cost of $ 1.25/WP with a PCE of 2.02% and a gain of 1.27.

Improvement of a Si solar cell efficiency using pure and Fe3+ doped PVA films

One of the most important key driving the economic viability of solar cells is the high efficiency. This research focuses on the enhancement of commercial Si solar cell performance by deposing a pure and Fe3+ doped polyvinyl alcohol (PVA) layer on the top of the Si wafer of the considered cells. The use of such polymer to improve solar cells efficiency is actually a first. The authors will rely on the optical characteristics of the pure and doped PVA films including absorption and emission properties to justify the effect on Si cells. Commercial monocrystalline silicon solar cells of 15cm2 (0.49V/460mA) are used in this work. Films of almost 80μm of the ferric polymer are deposed on the cells. Films with the same thickness are characterized by UV–Vis spectroscopy and photoluminescent emission of the films is then investigated. The electrical properties of the cells with and without the organometallic layer are evaluated. It will be deduced an important improvement of all electrical parameters, including short-circuit current, open-circuit voltage, fill factor and spatially the conversion efficiency by almost 3%.

Parameters extraction from commercial solar cells I–V characteristics and shunt analysis

In this paper, an optimized method on the basis of polynomial fitting and Lambert W function is presented to extract parameters from the current–voltage ( I–V) characteristics of commercial silicon solar cells. Since the experimental outcomes have significant impact on the precision of extracted parameters, polynomial fitting serves to overcome the obstacles of measurement noise in this method. The Lambert W function is employed to translate the transcendental equation into explicit analytical solution. Comparing with the as-reported parameters of a silicon cell and a plastic cell in the previous literature, the interesting outcomes demonstrate that the proposed approach is helpful for obtaining precise extracted data. This is further showed by the good agreements between the fitted I–V curve and the experimental results of a commercial monocrystalline silicon solar cell. Moreover, full extracted parameters of a badly shunted multicrystalline silicon solar cells before and after laser isolation process are conducted and investigated, the good fitting results finally show the validity of this attempt again.

Novel low-cost approach for removal of surface contamination before texturization of commercial monocrystalline silicon solar cells

This paper reports a novel approach on the surface treatment of monocrystalline silicon solar cells using an inorganic chemical, sodium hypochlorite (NaOCl) that has some remarkable properties. The treatment of contaminated crystalline silicon wafer with hot NaOCl helps the removal of organic contaminants due to its oxidizing properties. The objective of this paper is to establish the effectiveness of this treatment using hot NaOCl solution before the saw damage removal step of the conventional NaOH texturing approach. A comparative study of surface morphology and FTIR analyses of textured monocrystalline silicon surfaces with and without NaOCl pre-treatment is also reported. The process could result in a significant low cost approach viable for cleaning silicon wafers on a mass production scale.

A novel low cost texturization method for large area commercial mono-crystalline silicon solar cells

Texturization of mono-crystalline silicon for solar cell fabrication is still a key issue due to consumption of large amount of costly isopropyl alcohol (IPA) in conventional NaOH/KOH solution. The need of IPA arises due to the improvement in the uniformity of pyramidal structures and elimination of spots caused by bubbles sticking on the wafer surface during the texturization process. We investigated a new texturization technique for mono-crystalline silicon solar cells with tribasic sodium phosphate (Na 3PO 4, 12H 2O) solution with much less amount of IPA. The proposed texturization method of this paper is cost effective due to reduction in the consumption of expensive IPA. The cost comparison of our novel texturization approach with conventional NaOH texturization has also been reported in this paper. We are reporting for the first time such a novel approach of using tribasic sodium phosphate for texturization of mono-crystalline silicon surface with which solar cells of efficiency 14–14.8% are fabricated with more than 90% yield.

Role of hydrazine monohydrate during texturization of large-area crystalline silicon solar cell fabrication

Reduction of optical losses in monocrystalline silicon solar cells by surface texturing is one of the important issues of modern silicon photovoltaic. For texturization during commercial monocrystalline silicon solar cell fabrication, a mixture of NaOH or KOH and isopropyl alcohol (IPA) is generally used in order to achieve good uniformity of pyramidal structure on the silicon surface. The interfacial energy between silicon and electrolyte should be reduced in order to achieve sufficient wettability for the silicon surface which in turn will enhance the pyramid nucleation. In this work, we have investigated the role of hydrazine monohydrate as a surface-active additive, which supplies OH − ions after dissociation. This cuts down the IPA consumption during texturing without any loss of uniformity of textured pyramid. We are probably the first group to report such a novel idea of using hydrazine monohydrate addition in NaOH solution for texturization of solar cell. We were able to fabricate monocrystalline silicon solar cells with more than 85% yield in the range of 14–15% efficiency.

Low cost CBD ZnS antireflection coating on large area commercial mono-crystalline silicon solar cells

Zinc sulfide is a wide band gap semiconductor with high refractive index and hence a promising material for antireflection coating over commercial silicon solar cells. In the present work, attempts have been made to improve the rate of deposition, uniformity of deposited film, stoichiometry, refractive index and the percentage of reflection, respectively, by proper optimization of molar percentage of different CBD ZnS bath chemical constituents and deposition conditions. High values of the rate of film deposition (19.6 Å), film uniformity (S.D.<1.8) and refractive index (2.35) along with a low percentage of average reflection (0.655) are achieved with proper optimization of ZnS bath. We have successfully fabricated 13.8% efficient large area ( 103 mm ×103 mm) mono-crystalline silicon solar cells with CBD ZnS antireflection coating.

Low cost CBD ZnS antireflection coating on large area commercial mono-crystalline silicon solar cells

Zinc sulfide is a wide band gap semiconductor with high refractive index and hence a promising material for antireflection coating over commercial silicon solar cells. In the present work, attempts have been made to improve the rate of deposition, uniformity of deposited film, stoichiometry, refractive index and the percentage of reflection, respectively, by proper optimization of molar percentage of different CBD ZnS bath chemical constituents and deposition conditions. High values of the rate of film deposition (19.6 Å), film uniformity (S.D.<1.8) and refractive index (2.35) along with a low percentage of average reflection (0.655) are achieved with proper optimization of ZnS bath. We have successfully fabricated 13.8% efficient large area ( 103 mm×103 mm) mono-crystalline silicon solar cells with CBD ZnS antireflection coating.

XPS in‐depth composition study on commercial monocrystalline silicon solar cells

AbstractFrom large‐scale production, two monocrystalline silicon solar cells of different quality, i.e. ISC = 3.0 A (good cell) and ISC = 1.6 A (bad cell), have been studied by XPS combined with 4 keV Ar+ depth profiling. Depth profiling was carried out through the anti‐reflection coating (TiO2), the passivation layer (SiO2) and up into the phosphorus‐doped silicon bulk. At the solar cell surface the elemental composition is similar for both cells, although the bad one presents slightly more carbon, phosphorus and lead but less silver than the good one. During profiling, carbon and silver could be followed by XPS. It was found that the carbon content is distinguishably higher in the bad cell than in the good one. Furthermore, it was found that silver atoms have not diffused in the same way in both cells. Only the good cell presents silver atoms up into the silicon bulk. Copyright © 2003 John Wiley &amp; Sons, Ltd.